Hi all,
I'm finishing up the installation of my Magnum inverter (4K watt hybrid) and wanted to share a few numbers with you guys in case anyone is interested. My system has two 12 volt chassis batteries (for 24 volts) and four 6 volt golf cart batteries (for 24 volts.) The batteries are tied together by a 200 amp continuous duty solenoid that's triggered by the blower delay circuit on my MCI MC9. When the bus is running down the road the A/C units will, for all intents and purposes, be running off the alternator. The inter-tie can also be made manually by the switch momentarily, or turned off to isolate the batteries. There's a 200 amp Class T fuse in the inter-tie, and it uses 2/0 cable. All of the cables from the house batteries to the inverter are 4/0, and I was able to do it with about 4.5 feet of cable (one way.) There's a Class T fuse rated 300 amps in that line as well as a Blue Sea Systems switch rated at 500 amps. The only other thing is a 500 amp shunt in the inverter negative line to feed information to the Trimetric battery monitor. My bus has the 50DN alternator (24 volts.)
I ran my two 15K BTU Carrier A/C units yesterday to test the whole thing out and here's what I found. Each unit running on high with the compressor running draws 74 amps for a total of 148 amps at 82 degrees. That's 3552 watts. That's easily under what the inverter can handle, and the whole thing worked beautifully. I'm not saying do it like this, but this is what I'm doing and it seems to work in my situation so far. Hotter days will draw more amps, but I know that and can keep an eye on things to keep everything where it needs to be. So far, so good.
Hi Debo, must be quiet with no generator running, what happens when the batteries run low and voltage drops? Lvmci...
Your usage is right in line with what I saw, with a very similar setup - mine was 65 amps on low for one AC unit. Mine is manual switch not automatic and one AC not two. You only run the AC from the inverter when the engine is running, so you don't see any issues with voltage drop, in practice. Four golf cart batteries (which is what I have too) are only good for about 30 minutes of AC with the engine off. Mine are 230 AH at 24 volts.
Brian
So is the goal to be able to run the A/C during quiet times or?
I've read about people wanting to do that. It seems like hard use on a pretty large bank of batt's to me, but I suppose if it's dangerously hot and one cannot run the generator, then it would be worth it here and there.
I think a more practical non-standard use for the A/C-inverter formula is being able to run the A/C's while driving without starting the generator.
Being able to cool the coach while underway using the alternator's power seems like a practical goal.
Harder for me with a 12v system as a 200amp alternator is only putting out 2400w. I suppose it's ok to roll down the highway with the genset running....just feels weird to me putting hours on two engines at once.
As usual, my head goes back to the APU (auxiliary power unit) where there is an A/C compressor directly driven by a small (smaller than most generators) engine. It surprises me that more RV gen's don't have belt driven compressors but instead rely on a fuel to A/C to DC to battery to AC conversion....and then power yet another electric motor drive compressor from there. A lot of middlemen.
Edit: My coffee has kicked in and I see that underway powering of your electric A/C units is what you are talking about... sorry.
I'll probably do the same thing... it's just so darned inefficient in the end.
Quote from: lvmci on June 23, 2014, 09:24:32 AM
Hi Debo, must be quiet with no generator running, what happens when the batteries run low and voltage drops? Lvmci...
Sorry - forgot to add that. There's a 6K diesel genny for times when I'm not rolling down the road, or plugged into shore power. It's never my intention to run the A/C's purely from the batteries, although it can be done for short bursts. My inverter is capable of load sharing (shore power + battery) so a 6K genny will run them - even with the start-up load because the inverter can draw from the batteries for the extra juice. In practice, I don't plan on running everything wide open all the time, but we all know how "planning" goes, right?
Quote from: bevans6 on June 23, 2014, 10:04:23 AM
Your usage is right in line with what I saw, with a very similar setup - mine was 65 amps on low for one AC unit. Mine is manual switch not automatic and one AC not two. You only run the AC from the inverter when the engine is running, so you don't see any issues with voltage drop, in practice. Four golf cart batteries (which is what I have too) are only good for about 30 minutes of AC with the engine off. Mine are 230 AH at 24 volts.
Brian
Yep - exactly the same setup Brian. Working good so far, and I'll shake it all out before I do any real traveling with it.
Quote from: Audiomaker on June 23, 2014, 10:06:17 AMSo is the goal to be able to run the A/C during quiet times or?
I've read about people wanting to do that. It seems like hard use on a pretty large bank of batt's to me, but I suppose if it's dangerously hot and one cannot run the generator, then it would be worth it here and there. ...
You'll notice that Brian has said that his system will only run about 30 minutes and I'm guessing that that will pull the batteries down really far. While in theory, you could have a huge battery bank (that's spelled "$$$$$$$$$$") but you'd only be measuring in minutes, not like overnight. It really isn't practical to run A/C off of batteries for any extended period of time. A good thing about Debo's system is that he has many options for powering his system. He can run the engine and power off the engine alternator. Or he can stop and fire up the generator and use that as the power supply to the inverter (in this case, the inverter will probably be in "pass through" mode and the 120V from the generator will be going through to the A/C units. Another alternative would be to plug into "shore power" through a main cable; this would also be "pass through". Both the generator and shore power would run the A/C units and provide excess power to recharge batteries and run other loads on the bus. (The alternator on the bus would provide some extra power too but it doesn't look like there's a lot when both A/C units are running.)
About the only thing that you'd be able to do with batteries is to be able to keep the A/C going for a few minutes after the engine was shutdown and before one of the other power sources would come on-line.
But the idea of charging up your batteries and running the A/C all afternoon or overnight with no other power input? No, not practical for most people.
Bruce H NC USA
Quote from: Audiomaker on June 23, 2014, 10:06:17 AM
I think a more practical non-standard use for the A/C-inverter formula is being able to run the A/C's while driving without starting the generator.
Being able to cool the coach while underway using the alternator's power seems like a practical goal.
Yeah, running underway with the A/C on is the real reason for all of this. I don't use a lot of electricity at rest, and my battery bank should be sufficient for my needs. I'm an old sailor and used Nigel Calder's "Boat Owners Mechanical & Electrical Manual" to figure up all of my needs and size everything accordingly. I'd otherwise never need a 4K watt inverter, but having that A/C on running down the road with no generator running is nice.
The thing is, it can be designed to be extremely flexible. I do seem to recall that Sean the Boat Guy had around 12-odd batteries and could run one AC most the the night. But his setup was an extreme example for a bus. My long term plan is to build a DC generator and use it to power the inverter, making double use of the inverter and a DC generator can be designed to be very quiet, since it has no frequency maintenance requirement it can run at quite low speeds (same as any inverter-generator). But I immediately saw one big benefit to my setup on my last trip. The start batteries had been acting a little weird, but since I had them on a trickle charger they were up to their normal sitting voltage. They cranked the engine very slowly when I went to start, but they started it. I let them charge a bit, hit the switch to bridge in the house bank, turned on the AC and hit the road. Three hours later I got parked at my truck stop of choice, unbridged the starts and started watching TV. A little while later it became apparent I had parked in a high traffic area for the truckers instead of what I thought was a low traffic area so I went to start the bus to move to a less in-the-way spot, and the starts were dead. I just threw the switch to bridge in the house bank and carried on. Next night I measured and one start battery only had 10 volts, so I bought some group 31's and just left the start bank disconnected, ran just off the house bank for the next day until I could yank out the old 8D's and install my new Gp 31's. My set up has the flexibility to run the bus side off the starts only, the house bank only, or both combined, and run the inverter off the starts/house/alternator combined, or just the house bank alone. I can charge the house or the combined bank from the inverter. Being the honest lad that I am, I never designed in the ability to run the bus just off the house bank and I had to test it to be sure it worked (I couldn't remember exactly what connections the combiner switch made) but at the end of the day it worked great and probably got me out of a pickle...
Brian
Quote from: Oonrahnjay on June 23, 2014, 11:00:56 AM
A good thing about Debo's system is that he has many options for powering his system. He can run the engine and power off the engine alternator. Or he can stop and fire up the generator and use that as the power supply to the inverter (in this case, the inverter will probably be in "pass through" mode and the 120V from the generator will be going through to the A/C units. Another alternative would be to plug into "shore power" through a main cable; this would also be "pass through". Both the generator and shore power would run the A/C units and provide excess power to recharge batteries and run other loads on the bus. (The alternator on the bus would provide some extra power too but it doesn't look like there's a lot when both A/C units are running.)
But the idea of charging up your batteries and running the A/C all afternoon or overnight with no other power input? No, not practical for most people.
Bruce H NC USA
Well articulated Bruce, and exactly my thoughts.
Like I said, it's not for everybody, but I just wanted to be able to provide some real-world information to people tossing the idea around in their head. I think it's a very flexible system, and it fits my needs.
One odd thing, relevant to running AC units in a system with a Magnum 4000 inverter. I have a Yamaha 3000SEB generator that runs my AC unit flawlessly. I also have a 15 amp plug in my shop that I sometimes use to run the AC, and it runs the AC flawlessly as well if the day is sorta cool. I couldn't get the AC to start on either with the Magnum in the circuit. Even with the Magnum turned off, both charger and inverter, from the remote panel. What would happen is I would start the AC compressor, the Magnum would interrupt the circuit for a second or two, it would start to invert, it would realize that it was supposed to be turned off, and then after sitting for another second or two it would let the AC compressor start on the generator or the remote feed. What was happening was I had the Magnum's low voltage cut-out set at 100 volts, which seemed reasonable to me, but the start surge on both was enough to drop below 100 volts for an instant. I reset the low voltage cut-out to 90 volts and all was normal again. Dang overly smart inverter! Mine is not the Hybrid version - the Hybrid version would probably bolster the supply in some way.
Brian
Running A/Cs under way are going to burn up extra fuel whether you run them from the alternator, or from the generator. I figure you're taking away from the main engine's power when putting that much load on the alternator so I just run the generator. If you're mostly a flatlander it won't matter so much.
Isn't this a reason to consider mini-split A/Cs, especially the inverter versions - they use much less power than typical RV roof-warts, so one could run them off batteries for a reasonable time, or off alternators smaller than 50DNs. Yes, I know they cost more initially, but for folk with different needs than most they could be useful.
Food for thought?
John
Quote from: Iceni John on June 23, 2014, 01:00:58 PM
Isn't this a reason to consider mini-split A/Cs, especially the inverter versions - they use much less power than typical RV roof-warts, so one could run them off batteries for a reasonable time, or off alternators smaller than 50DNs. Yes, I know they cost more initially, but for folk with different needs than most they could be useful.
Food for thought?
John
My own personal thought on this is that if one wants more air cooling, then the best way is to improve on the mechanically driven system rather than trying to do the wattage fight.
Has anyone looked at the A/C issue from the perspective of what can be done to, or added to the mechanically driven system?
You have to do the math at some point. At $450 that I paid for a new 15K btu Briskaire, not sure how many mini-splits you can buy. In my area, about a quarter of one, then you have to install it, get it charged, all of that. Numbers do not work for me. As far as the mechanically driven system, it might work great for you forever, but mine needed around $2500 to recommission, and an estimated $1,500 a year to maintain, and finding someone to do the work is literally impossible. Numbers do not work for me. As far as running the generator, I need to pull 2.4 hp from my main engine. That is around .75% of it's capacity, and the fuel usage is literally in the noise, as is the impact on performance. It takes around 20 times that to simply make my engine spin at 1800 rpm, and a 2 mph difference in headwind overcomes that drag cost handily. The cost to run an AC from the main engine is essentially free once the infrastructure is in place. The cost of a typical 6 KW generator that can run OTR is at least 3 times the cost of my total infrastructure. Once again the numbers do not work for me. I do have a gas generator that I carry, the Yamaha, but I need that for emergency backup at home anyway.
Everyone has their reasons for doing what they do, but I am Scottish, and I spent the least amount of money possible to do what I am doing. Pennies scream when I pinch them! It really is a good solution.
Brian
It's funny, the numbers work opposite for me. We need a good onboard generator anyway, so using it to run the AC's while traveling does not entail any extra cost. Since driving the bus most be about $.75/mile, the added generator fuel is not significant. I would like to be able to run one AC through the inverter, but I would need a bigger alternator to start with. Is there any extra wear issue for the AC unit running on modified sine wave?
Quote from: Lin on June 23, 2014, 04:21:05 PM
It's funny, the numbers work opposite for me. We need a good onboard generator anyway, so using it to run the AC's while traveling does not entail any extra cost. Since driving the bus most be about $.75/mile, the added generator fuel is not significant. I would like to be able to run one AC through the inverter, but I would need a bigger alternator to start with. Is there any extra wear issue for the AC unit running on modified sine wave?
I don't understand. You say running the generator to power the AC unit(s) does not add significantly to the fuel cost, but then you ask about running an AC on inverter?
I doubt if any AC unit knows if it is on shore, generator or inverter power, but if you are running it on inverter you are adding heat to the alternator which has to generator the power, and the engine is working harder to run the alternator.
I fully support the use of generators to run the house AC systems while driving in a coach not equipped with engine powered full coach AC.
Debo, thanks for the numbers. Our 4024 Magnum inverter is non-hybrid, but it is, none the less, a phenomenal machine. Reading about your setup helps me think about mine.
We full time in our 40' Gillig, and we're midway through our second year of doing so off grid. Four 255w Samung panels are our primary power, but we have an old 4500w Kohler gen set for backup. Four 8D AGM batteries give us 490 amp hours at 24v.
The reason I'm so interested in your experience is that I'm about to add AC to the mix. We survived last summer — and this one so far — with fans only, but we'd like to have an AC option. I'm planning to use the smallest, cheap window unit I can find, cut a hole for it high in the bulkhead wall above our headboard, and run it most afternoons — and especially hot nights — on the battery bank. We removed the original air handler early in the conversion, and I've always planned to put a small AC there. I do not have autostart for the generator, but I have the auto shutoff feature on the inverter set to its highest voltage. I think we can have air con when we need it most without damaging batteries.
Obviously, I will not try to cool the entire bus with such a small unit. Our bedroom/bathroom will soon be isolable from the rest of the living space and well insulated. We can retreat there on especially hot days. We are trying to live on a "solar budget", and we will not install larger capacity AC.
My plan for charging house batteries while the engine is running is to add a high capacity, 24v alternator to our 40 Series Detroit and drive it with a separate belt. That step is not motivated by a desire for AC, but it could easily run such a small room cooler while we're driving. When we're traveling, the solar panels alone should keep up with all our electric needs, but I like having charging options. Generators do break down. I have shore power capacity but seldom use it.
I do appreciate the time you spent measuring loads and writing about your setup.
Jim in NC
Quote from: Lin on June 23, 2014, 04:21:05 PM
Is there any extra wear issue for the AC unit running on modified sine wave?
The inverter he's using is pure sine wave.
Jim in NC
Jon-- There's no contradiction. I said I am fine with using the generator for OTR AC. However, doing it off the engine alone is also okay but not worth the investment for me. I also asked if running an AC unit on a modified sine wave inverter would effect the life of the unit out of interest in the answer since I presently use (notice I did not say currently) a modified sine wave inverter.
Quote from: bevans6 on June 23, 2014, 03:00:48 PM
You have to do the math at some point. At $450 that I paid for a new 15K btu Briskaire, not sure how many mini-splits you can buy. In my area, about a quarter of one, then you have to install it, get it charged, all of that. Numbers do not work for me. As far as the mechanically driven system, it might work great for you forever, but mine needed around $2500 to recommission, and an estimated $1,500 a year to maintain, and finding someone to do the work is literally impossible. Numbers do not work for me. As far as running the generator, I need to pull 2.4 hp from my main engine. That is around .75% of it's capacity, and the fuel usage is literally in the noise, as is the impact on performance. It takes around 20 times that to simply make my engine spin at 1800 rpm, and a 2 mph difference in headwind overcomes that drag cost handily. The cost to run an AC from the main engine is essentially free once the infrastructure is in place. The cost of a typical 6 KW generator that can run OTR is at least 3 times the cost of my total infrastructure. Once again the numbers do not work for me. I do have a gas generator that I carry, the Yamaha, but I need that for emergency backup at home anyway.
Everyone has their reasons for doing what they do, but I am Scottish, and I spent the least amount of money possible to do what I am doing. Pennies scream when I pinch them! It really is a good solution.
Brian
Thanks for layout of your math Brian. I run similar numbers myself to try to find efficiency. I didn't realize you weren't running a generator.
Doing a little bargain shopping one can probably retrofit a generator head to the main engine. I have considered it, but in my case I'm told the DD 6-71 shouldn't idle when avoidable...and that kinda killed the idea for me.
As for the mechanical system, well my engine driven A/C would not keep this whole rig cold but it was never designed to carry passengers underway, so I've kind of had a mental short circuit on the idea of running electrical A/C's on a moving bus...wondering if there's something wrong because at some point wasn't the factory system supposed to keep the passengers cool?
Also, don't forget that you can run an engine-driven compressor A/C (takes some elec power to run fans, usually 12 or 24V) and also one or more roof wart or mini split systems at the same time. You can do an engine compressor from an auto junkyard (usually a gamble, however), rig up a bracket and run a V-belt and then do the "other end" (condenser, evaporator, blowers, etc.) using "Red Dot" components -- just be sitting down when you read the prices in the catalog. It would probably take a very unusual $$$ profile for it to make sense, but it can be done.
BH NC USA
It's important to note in my math that I have the original 50DN belt driven alternator on the bus - if you didn't have such a beast you'd have a different equation to work with. Similarly if your bus came to you with a generator that you can run over the road - no extra investment on your part. My generator can't be run OTR, it's a little air cooled inverter-generator and it would overheat. Lots of ways to win with this deal.
Brian
Sorry, this got a bit long...
Cool! This has turned into a pretty interesting thread! For me, the design of my system was really about two things: a.) simplicity and maintenance requirements, and b.) future cash outlay. I think it's important to disclose those, because how we all outfit our buses is a very personal thing. We all have different requirements and experiences. I'm going to retire in a couple of years and be on a fixed income, so I wanted things I could repair or replace myself for modest cost anywhere in the country. No special order parts, no bank-breaking single item. I also come from an aviation background, so I appreciate simplicity and low parts count. There's just less that can go wrong. Just for discussion, I'll give you some of my reasons for making the choices I did:
1. The battery inter-tie was a no brainer. It was clear to me that to run A/C off batteries for any real length of time would be unsustainable, so I'd have to run off the alternator while driving over the road. I also like the idea of being able to manually activate it and jump the chassis batteries in a pinch, or deactivate it completely. I made it automatic, because sooner or later I knew I'd forget to switch it over and kill my house batteries. I have to admit, I scratch my head a little when people with that big 50DN 24 volt alternator like I have (lucky) don't want to use it. When the coach was in service, it was running practically the same load placed on it by my system with the factory OTR blowers and air. I know it places a load on the engine, but I just don't see this as significant and apparently the original designers didn't either. Personal choice. Yours may be different and that's cool.
2. I chose a smaller generator for less maintenance, less noise, and lower replacement cost. Also, I just never could get comfortable with the idea of a generator running down below while I wasn't able to give it my attention (driving.) It's fine if that's an unfounded opinion. Based on my experience it's the right decision for me though. In my eyes, machinery running + lack of attention = trouble.
3. It's a pure sine, because it will run everything efficiently. Probably puts out cleaner power than the power company.
4. My OTR air was going to be horrendously expensive to fix and maintain, and I wasn't about to run the bus engine every time I wanted the air on. I probably pulled 2500 pounds worth of stuff out of there removing it. Talk about fuel savings...
5. I can buy replacement rooftop A/C's for relatively low cash outlay and install them the same day in the same hole. I don't think they're gorgeous either, but simplicity, ease of maintenance and replacement, and replacement cost trump that in my opinion.
6. As far as any extra fuel consumption from running the alternator with a load on it, that's just the cost of doing business to me. If I want the air on (and I do) it might cost me a MPG or two. If I don't have enough money for fuel with the A/C on, I don't have enough money for fuel. Plus, I can always turn the air off and it's the same load as always on the alternator.
I really don't see this as a "who's right or wrong" thing. We all have different needs and backgrounds, and how you outfit your coach is going to be different from how I outfit mine. My decisions have all been based on literally years of thinking about it and my personal experiences. If anyone wants to PM me to know more, feel free. This is an interesting topic to me. I'm no expert, but I have blown a lot of S#&t up over the years. ;D
Quote from: Debo on June 24, 2014, 04:06:09 AM... I really don't see this as a "who's right or wrong" thing. We all have different needs and backgrounds, and how you outfit your coach is going to be different from how I outfit mine. My decisions have all been based on literally years of thinking about it and my personal experiences. If anyone wants to PM me to know more, feel free. This is an interesting topic to me. I'm no expert, but I have blown a lot of S#&t up over the years. ;D
Couldn't agree more.
It's how we learn! I liken this forum to a campfire - we all have different experiences and backgrounds, and we teach each other just by talking about things. One time we were talking about pure sine vs modified sine, and a guy said "pure sine is just a fancy square wave inverter" or something like that. "No it ain't" I said to myself, and then spent an hour finding out how pure sine wave inverters work. Turns out they are fancy square wave inverters that put out a string of square wave pulses at around 20 KHz, push that through a filter and out pops a pure sine wave... A little later I found out that a Vanner voltage equalizer is basically the same thing as a pure sine inverter, it just does something else with the output. Whoda thunk?
Brian
Quote from: Debo on June 24, 2014, 04:06:09 AM
I really don't see this as a "who's right or wrong" thing. We all have different needs and backgrounds, and how you outfit your coach is going to be different from how I outfit mine. My decisions have all been based on literally years of thinking about it and my personal experiences. If anyone wants to PM me to know more, feel free. This is an interesting topic to me. I'm no expert, but I have blown a lot of S#&t up over the years. ;D
No, the saying goes "no rules, only guidelines".
I bumble in here and make matters worse because I know a fair amount about energy, living off-grid, and mobile systems, but I don't know bus specifics, nor whose bus (or bus model) has what.
There's also huge differences in how people need to use their energy systems, and what their budgets are.
For me, I'm dead without my generator. It's third in line after the engine and transmission.
My life circumstance is that I could never go down the road running the genset for the sake of A/C because I need to hear if something is going wrong back there just in case.
For me, even shopping on ebay or on Craigslist for bargains, I am limited to only a couple models that would fit, and they might not be available used...which means about $8k new, or more realistically, no generator if it blows and I go back to the stone age.
On top of the pricey generator, I also have a used inverter system which cost about $1500 to put together so far without even having another $1000 worth of needed battery bank.
I feel all this stuff is pretty fragile compared to the things that could go wrong in an engine driven A/C system. I feel a lot more comfortable with the idea of blowing an A/C compressor than the gen/inverter system because in theory all I should lose is the air conditioning, not the whole game.
So not knowing that a coach doesn't have a engine driven A/C system, or a generator definitely changes the equation. If it did, I would wonder why someone would put the hours on the electric system vs the mechanical.
I've also blown a lot of crap up in my days, and I tell you a story about one such instance...
One day I was rushing home from work in my turbocharged car because I had to pee...real bad.
I pulled in to my driveway, but someone had their car parked there so I pull off into the grass and ran in to relieve myself.
Granted, this was a reasonably long p*ss, but when I came back outside to get my things, the entire car was engulfed in flames.
Seems there was some tall dry grass where I pulled off and it interacted with the turbocharger.
Need to pee = bonfire. It's hard to say what can happen, but you can usually narrow it down to what is operating at the time.
The point is that another angle on the cost equation is to factor in what needs to be functioning for that A/C to operate, and what is at risk during that operational time, and what could the loss of that system result in (including incidental losses).
A turbocharger and a piece of grass lost me a whole car. Simply, if it had not been running, that car would have driven me to work the next day.
For for my particular engine, I'm not supposed to let it idle. Your engine may be just fine with this, but even if I had an idle-friendly power plant, I'd be nervous about letting that system run just to make myself comfortable. There are instances when A/C might be a matter of life and death, but excluding those, I am the type who can't relax while an engine is running mostly unattended.
So you can see, for me at least, the idea of the prime mover online, spinning an alternator, going to a inverter, to a charger, to a big hydrogen producing battery bank, to a pair of electric motors...and having the whole thing bouncing down the road while concentrating on bad drivers is a little scary. Running the generator if you have one isn't much better.
Sure, if you're going down the road, the prime mover has to be operating. There is no avoiding it, but during that time my preference would be that the luxury of A/C was a cold and isolated system who's failure would only result in sweating a lot.
If that's not possible, I understand, but that was the basis of me suggesting to tackle the mechanical system first to see if it could be made to cool the coach while underway.
Cheers!
Sean
Quote from: Debo on June 24, 2014, 04:06:09 AM
I'm going to retire in a couple of years and be on a fixed income....
I'm jealous of people with fixed incomes. We have to get by on a broken one.
Quote from: Lostranger on June 24, 2014, 10:08:00 AMI'm jealous of people with fixed incomes. We have to get by on a broken one.
Hey, Jim, speaking of fixed, do you have any photos of your solar system? Do you have a meter to tell you what kind of power you're making? If so, what do you see at the peak sunshine times? And what engine is in your Gillig? Best wishes, BH
Hey Bruce. Good to hear from you.
The only metering I currently have on the solar is the volt meter on the remote for the Magnum ME4024 inverter and the LED state of charge lights on the MorningStar 60 amp MPPT charge controller. Ammeter and battery level meter are in the plans but not near the top of the priority list today. What I currently have shows that the batteries get full charge even on the cloudy days we're having lately and in spite of the fact that we're in shade half the day. I think the MorningStar gets a lot of credit, but I'm also pleased with the panels.
Until April of this year, I was using a bank of six group 27 AGM batteries. I was unwilling to use more than six because my research convinces me that it's a bad idea to use more than three strings of batteries in one bank. Two strings is apparently even better. I don't actually KNOW this, but it's what people who apparently do know tell me.
I realized early on that the group 27s were inadequate, but I thought we would get by for a couple years. The coldest winter in memory convinced us otherwise, and in April I replaced them with 4 8D AGMs. That was a marvelous move. Here is what they look like with their new 2/0 copper cables still in kind of a tangle:
(https://busconversionmagazine.com/forum/proxy.php?request=http%3A%2F%2Fi62.tinypic.com%2F29mmwch.jpg&hash=4dc2d8ad6154045543ed17618450ba02dfb4ccfc)
The batteries sit on the original floor level, on the passenger side of the bus, just to the left of the door as one enters the bus. The gray-colored steel channel in the photo is the floor frame for the five foot extension I built next to the higher floor in the rear of the bus. Our full-size front load washer and dryer sit directly above the batteries with a hand sink between them. I have to move the washer and dryer to get to the batteries, but with AGMs, that does not happen often.
I still only have two of my four 255w panels mounted on the bus. We use all four panels at home and disconnect the two that are not mounted when we travel:
(https://busconversionmagazine.com/forum/proxy.php?request=http%3A%2F%2Fi59.tinypic.com%2Fv6iwis.jpg&hash=60b2950924bccf4a114d9db76d7c51efb6998e73)
This industrial cart and some 2x4s works amazingly well as a non automated solar tracking ensemble. We got along last summer with only these two panels. We were still living in the truck, and our power needs were small. In September (I think) I got the other two panels on the roof:
(https://busconversionmagazine.com/forum/proxy.php?request=http%3A%2F%2Fi58.tinypic.com%2F2mni3di.jpg&hash=ef631556cbc1951af7e75968fbac0247a987cc30)
(https://busconversionmagazine.com/forum/proxy.php?request=http%3A%2F%2Fi59.tinypic.com%2Fnvqh45.jpg&hash=9964ac0d449445f46ec2528fd058f9f5e0eff8d5)
(https://busconversionmagazine.com/forum/proxy.php?request=http%3A%2F%2Fi59.tinypic.com%2F2l8c2du.jpg&hash=27f28f0392e963c8bc242a27a56a86cc6eecdb76)
These panels are mounted just aft of the rear roof vent, and that puts them over the bedroom. The other pair will mount just fore of that same vent.
I'm pleased with the mounting system except that I don't like the looks of the 12" sections of aluminum channel that bolt to the sides of the bus. I have since acquired a sheet of 3/8" tempered aluminum sheet from which I will cut side mounts for the other panels and to replace these.
That same channel does a wonderful job of spanning the roof and holding the panels. One of my design parameters was no holes in the roof. This mount is stable and secure at any speed we travel. The actual connection to the bus is via 3/8" SS bolts through both outer and inner aluminum bus wall segments. The nuts show on the inside, but they will all be covered by cabinets.
Don't know if this is what you wanted, Bruce, but I hope it's helpful. My original plan was to buy an 8 or 10 KW generator head and put it on one of the Isuzu/Thermoking diesels I have on hand. I was planning to put that where the original air handler was. With our solar panels and the fact that we decided we can live without two or more large AC units, the big generator would be silly. We could get by with 2000 watts of Honda or Yamaha for backup, but since we already have a good 4500 watt Kohler out of our old motorhome, I have spruced it up and am currently working on getting it installed above the engine. Run what ya brung, as they say.
I believe you also asked about our prime mover. This is my first experience with a DD Series 40. It's the larger one, 8.7L. Lots of opinion floating about what this motor is, but this is what I believe to be true. It is not exactly the same as the motor sold under the International brand. IH builds the long block, but apparently Caterpillar makes the fuel delivery system and DD ties it all together with proprietary management software.
All I know for sure is that this thing is a hoss! It's rated at 330 HP. That's the same figure as our old 6V92TA, but this bus will run circles around the Flxible Metro. Plenty of power and speed. No Jake, but I've become a fan of that Allison retarder.
Jim in NC
Interesting looking solar mounting system. It's good to know that you are getting a decent charge even in the shade. One of the reasons that I decided not to do solar on the roof was that most times we want to be in the shade and I was told it would not work.
Quote from: Lostranger on June 25, 2014, 06:33:08 AM
<snip>
Don't know if this is what you wanted, Bruce, but I hope it's helpful. My original plan was to buy an 8 or 10 KW generator head and put it on one of the Isuzu/Thermoking diesels I have on hand. I was planning to put that where the original air handler was. With our solar panels and the fact that we decided we can live without two or more large AC units, the big generator would be silly. We could get by with 2000 watts of Honda or Yamaha for backup, but since we already have a good 4500 watt Kohler out of our old motorhome, I have spruced it up and am currently working on getting it installed above the engine. Run what ya brung, as they say.
<snip>
Jim in NC
That's a nice setup. If you don't mind me saying, by my way of thinking, if you do start considering a diesel generator in the future, a used APU seems like it might fit your bill. At about 24" wide, they put out about 4kw (some vac, some vdc only). Small by comparison to most generators, but enough to charge batteries, and if it's hooked up, you get one of those A/C's that you've decided to forego along with it (using none of that 4kw of electrical generation). Heat too. Probably only affordable by those who are willing to buy used and tinker, but you did mention mounting generator heads onto different engines so I guess you're game for projects.
I get excited seeing solar on people's rigs. Aside from a boat, I can't see a better use of it. I mean, RV's and marine are by nature...off grid right from the start, whereas houses are designed to be on grid yet usually are the first to get PV's.
Thanks for the pic's!
Quote from: Lin on June 25, 2014, 08:46:19 AM
One of the reasons that I decided not to do solar on the roof was that most times we want to be in the shade and I was told it would not work.
Lin, of course your situation will be different than mine, and of course those panels have to have SOME sunshine to work with. We base on a spot with lots of shade because it puts us close to sewer and water. This time of year we probably get around 5 hours of sun. About the same in winter because the leaves are off.
With that said, I AM amazed at this system's performance. It's a joy to watch battery voltage come up on cloudy days. AND, at night I point the cart mounted panels toward a nearby street light. We get some gain that way. Part of it is high capacity panels. 1020 watts is much more than would fit in that space even a few years ago. Mostly, though, I thank the MPPT controller.
Audiomaker, tell me more about APU. I don't know what that is, but I'm not afraid of a project. You should see my yard. On second thought, maybe it's best you don't.
Mobile houses and solar power are a natural fit. I confess, though, that I never considered taking a bus off grid until I first read Rob Gray's build thread in 2010. He made it seem so obvious. www.graynomad.com (http://www.graynomad.com)
Our build thread is here: http://www.nomadicista.com/viewtopic.php?f=4&t=2541 (http://www.nomadicista.com/viewtopic.php?f=4&t=2541)
Best to all,
Jim in NC
Quote from: Lostranger on June 25, 2014, 12:48:17 PM
<snip>
Audiomaker, tell me more about APU. I don't know what that is, but I'm not afraid of a project. You should see my yard. On second thought, maybe it's best you don't.
Too late, but I'll make it short. An "APU" or "Auxiliary Power Unit" is a small (usually 2cyl) self contained diesel unit designed to power the things that OTR truckers used to keep their engines running to power. In other words, it is supposed to power everything the engine does except moving the truck. They usually have a high capacity alternator, an A/C compressor, and a heat exchanger.
Outboard of the main unit is the remote A/C blower unit that they install in their sleepers. The heat exchanger is routed either through the trucks engine where the driver uses the factory heating core and fans to heat the sleeper, or sometimes a heater exchanger can be installed elsewhere in the sleeper. The advantage to doing the engine circuit heat is that the engine is warm when they wake up and want to get going.
In some cases, the electric or cooling is also routed to a refer trailer...etc.
They were more of a luxury in the past, but as more states pass anti-idle laws, they are now on most OTR trucks.
The disadvantage of an APU vs a regular generator is that they don't generally have enough wattage in comparison, but the advantage is that they have mechanical A/C and heat built in which is normally the biggest draw on a generator/inverter system, so one can get away with a lower amount of electric since you're mostly just charging batteries.... especially if you can supplement it with solar (which the truckers don't).
The units are pretty small...about 2' wide, 25" high, and maybe 30" or so deep.
Because they've been around for awhile now, they get pulled from scrapped trucks, or as part of the service program on fleets.
You can find them on ebay and such... often pretty rough looking, but if you get one that runs and has a rebuildable diesel in it, you can probably put a rebuild on the "later" list.
I have friends who drive truck, and they love the things. I hear all about how they keep the sleeper warm...or cool...etc.
"Warm and cool" are what my generator/inverter system struggles with. A/C and electric heat are the big energy hogs, so it's smart how they get around that with the APU setup where those two items are mechanical.
Although I suppose most people don't use electric heat, most can, and I kinda laugh and wince at the same time when my 7k generator is pushing my 1500 watt heater. A tiny bit of heat from the heater, and massive heat from the wasted generator's radiator to do it.
The APU uses that engine heat, and that's smart in my book. At least its smart enough to explain why cars don't come with electric heaters and electric a/c's...which is what the RV crowd seems to end up with.
:)
the "graynomad.com" link is dead - gets you a "For Sale for $2,095.00" notice.
Interestingly this thread has now begun to discuss alternatives to typical RV/conversion A/C needs. Further to my previous question why mini-splits aren't more popular, I'il be using one simply because I cannot run a typical roof-wart for long off my solar panels, but a mini-split drawing only a fraction of the power is well within my panels' capacity. I have eight Sharp 255W panels, giving me 2,040 theoretical watts, and they will feed two Morningstar TS-MPPT-60 controllers to charge two separate battery banks, each bank being eventually four golfcart or L-16 batteries. (Sort of Jim times two.) With that much power I can easily run a mini-split or a 5,000 BTU window A/C, but probably not both together.
I've made a walkway that runs along the 26 feet of space between my two roof hatches, and from this walkway will be hinged the panels, or more specifically the panels' support frames (each panel will sit in its own support frame made from 6063 angle). Each panel can sit down against the roof at about 20 degrees down (the ideal angle for SoCal summers!), or at horizontal, or at 20 or 30 or 40 or 50 degrees up (for winter sun), with all their cables and combiner boxes protected under the walkway. There will be absolutely zero shade on any panels at any time from anything on the bus. As long as I can park in an east/west direction I should get good insolation, and even if I can't I should still get lots of usable power, likewise on cloudy or dull days. One other incidental benefit is that almost my entire roof is shaded this way, hugely reducing the sun's heatload onto it, and somewhat reducing interior temperatures.
I want A/C, but without needing to ever run a generator for it. I think my setup will work well for me - whether it's useful for other folk is up to them, but as they say "Do it your way"!
John
Quote from: Iceni John on June 25, 2014, 04:33:07 PM
Interestingly this thread has now begun to discuss alternatives to typical RV/conversion A/C needs. <snip>
John
Well, for some the season is already here. For others (like myself) it's coming soon.
I'd love to see or watch your solar install progress. I have a similar plan as I have room for 10 of the 250 watt panels.
I don't know if the thread has really gone off topic... I mean you could call it "how many ways can someone power an air conditioner?".
The OP can power his it seems from his engine's alternator and that's pretty cool (ack!).
The solar equation is pretty intriguing too for those who have enough real estate to even consider it. The idea that the hotter it gets outside, the cooler it could be inside (for free) is a fun challenge.
Quote from: shelled on June 25, 2014, 03:53:15 PM
the "graynomad.com" link is dead - gets you a "For Sale for $2,095.00" notice.
I apologize. try www.robgray.com (http://www.robgray.com)
Quote from: Audiomaker on June 25, 2014, 03:48:56 PM
An "APU" or "Auxiliary Power Unit" is a small (usually 2cyl) self contained diesel unit designed to power the things that OTR truckers used to keep their engines running to power.... They usually have a high capacity alternator, an A/C compressor, and a heat exchanger....
Well powder my butt with flour and call me a biscuit! What rock have I been under while this little development rocked the trucking world? I'm too much in shock to say whether I'm happy or sad to have made the APU connection, but I do know that I gotta have one. Would tie up many loose or semi fixed ends in my conversion.
So happens that we need to build a small walk-in cooler for the organic produce business....
Thanks, Audiomaker, or curses! Depends on how much of an investment this turns out to be.
Jim in NC
Quote from: Lostranger on June 25, 2014, 06:18:14 PM
Well powder my butt with flour and call me a biscuit! What rock have I been under while this little development rocked the trucking world? I'm too much in shock to say whether I'm happy or sad to have made the APU connection, but I do know that I gotta have one. Would tie up many loose or semi fixed ends in my conversion.
So happens that we need to build a small walk-in cooler for the organic produce business....
Thanks, Audiomaker, or curses! Depends on how much of an investment this turns out to be.
Jim in NC
Well the bright side might be that they usually sell to truckers...who don't need projects. They just need to get back on the road.
To that end, "project" APU's can be had for under a grand.... I've seen them as low as $500. I suppose that's about the same game as a generator. Better off to get one with at least the cabin A/C unit still attached as I wouldn't want to piece that together.
Those are eBay #'s. Junkyards and such you might do better (and not have to ship).
Anyway, just something to research in your spare time and see if it might fit.
All the Best
"While in theory, you could have a huge battery bank (that's spelled "$$$$$$$$$$") but you'd only be measuring in minutes, not like overnight."
I have bus AC for going down the road and I run the generator when stopped overnight if it is really hot. However I can and do run one roof air for 8-10 hours overnight off batteries on a regular basis. I have 8 4D batteries. I thought it was overkill until I realized the full capabilities of a big battery bank.
Davy
Quote from: DKO on June 25, 2014, 09:04:07 PM"While in theory, you could have a huge battery bank (that's spelled "$$$$$$$$$$") but you'd only be measuring in minutes, not like overnight."
I have bus AC for going down the road and I run the generator when stopped overnight if it is really hot. However I can and do run one roof air for 8-10 hours overnight off batteries on a regular basis. I have 8 4D batteries. I thought it was overkill until I realized the full capabilities of a big battery bank. Davy
A roof air? What amps does it pull? It's great that you have it worked out to do that - not too many people have been successful. How many amp hours is your battery bank rated for? How far down on "State of Charge" does an overnight pull it down? Is 8 4D's the equivalent of 4 8D's?
Thanks for the info! BH NC USA
Quote from: Lostranger on June 25, 2014, 06:33:08 AMHey Bruce. Good to hear from you. ...
And you! Thanks for that info. I was especially thinking about panels (I see you're just over 1000 watts) and the charge controller -- that Morningstar controller must be really making the most of every bit of power from the panels. Good to hear about your battery bank. Does 4 8D's give you a total of about 930 amp/hours, total (limited to about 460 to go from full to 50% State of Charge)?
I like your "manual" aiming device; it's clear that keeping panels at a right angle to the sun makes a bid difference. Yes, lots of detail there and i thank you for that.
I have heard some not-nice things about the Detroit 40 series engines but you don't run generalities -- you run what's in your bus. I was thinking that a Cummins ISC 8.3 would be nice, too, and yeah, the retarder sounds really sweet. Not that I've really been thinking much about it.
Quote from: Oonrahnjay on June 25, 2014, 11:32:14 PM
Does 4 8D's give you a total of about 930 amp/hours, total (limited to about 460 to go from full to 50% State of Charge)?
I like your "manual" aiming device; it's clear that keeping panels at a right angle to the sun makes a bid difference....
I was thinking that a Cummins ISC 8.3 would be nice....
The retarder sounds really sweet. Not that I've really been thinking much about it.
Bruce, my battery bank is rated 490 amp/hours at 24v. We refer to the Manual Solar Tracking Ensemble as the NASTY. I've already come to the conclusion that, should a repower become necessary, it's ISC for me.
You know, you're not really gonna be happy until you buy a wrecked Gillig and slip the engine and drive train under your Daimler. Who knows, in the process, you might even lower it enough to be able to paint the roof.
Quote from: Oonrahnjay on June 25, 2014, 10:34:35 PM
A roof air? What amps does it pull? It's great that you have it worked out to do that - not too many people have been successful. How many amp hours is your battery bank rated for? How far down on "State of Charge" does an overnight pull it down? Is 8 4D's the equivalent of 4 8D's?
Thanks for the info! BH NC USA
My roof airs are 13.5 Duo Therm Penguin's by Dometic. I added them in 2009 and removed the original Cruise Air units.
The display in my coach shows about 3 amps with the fan on low and 10-12 more amps with the compressor running. I do not know exactly how accurate that is but it is consistent.
Honestly I do not know the amp hours on the batteries and I can not take credit for the set up. I am the 3rd owner but as far as I can tell this was the standard set up for a Vantare conversion of my vintage. The batteries were very weak and beyond their life span when I bought the bus in 2008. When I found out it had 8 batteries I was bound and determined to figure out how to put fewer batteries in when I replaced them. I was cautioned by several folks that I needed to understand my system better before I tinkered much with the engineering because ALL the electric runs through the inverters on a Vantare. There are no "inverter circuits" and "non inverter ciruits" in my bus. Everything runs through the inverters and everything has the potential to be ran on battery power in theory. I never get close to the amp threshold but the inverters will bring the generator online the amp pull reaches a certain set point.
I decided to replace all 8 batteries the first time and completely diagram all the battery and inverter wiring while I was at it so that I could better know the system and figure out how to reduce to 4 batteries the next time they need to be replaced hopefully 5-7 years down the road.
But, after living with the convenience of 8 new batteries and the freedom that gives me I will probably never downsize to 4. When my batteries were shot and I pulled into a Flying J or WalMart for the night while traveling, I had to turn on the generator within and hour if I wanted even the fridge to run. I had no flexibility at all. My options were either shore power or generator if I was stopped. I was fine with that because that is all I had ever known. I basically go from shore power to shore power every week in a new location. The only exception is travel days.
After I installed new AGM batteries I had a whole new realm of possibilities. Stopping for the night is absolutely no problem now. We run the fridge, a fan, all of our computers and chargers and do not have to worry about it. I did change about 30 halogen lights to LEDs to eliminate those amps. If it is a little warm then I turn one air on and run it as much as I need it although I do keep a close eye on the numbers. If it is warmer and we need more than one AC or my wife needs to cook then I do not hesitate to start the generator.
The conversion companies have invested a lot of time and money into engineering the electrical systems. They all do something a little different but they do it for specific reasons. If I was building something from scratch
(I could not but I absolutely admire you guys that can) I would try to look at every system I could and take the good from each.
I do not have anything that tells me the percentage of charge but as long as my inverters are telling me the battery voltage is 25 or above I am satisfied. If it gets too low I have it set to auto start the generator but I watch it close and start it manually.
Davy
Davy has words of wisdom. It is true everyone has different needs and ideas so there is no one perfect way to do things. But his point about professional conversions being well designed and thought out is absolutely correct. The fact that the converters all seem to have their own way of doing things lends a great deal of credibility to the fact there is no one best way.
My conversion is unlike Davy's, but like Davy's it works well for my purposes but goes about how it does things in a different fashion than Davy's. The point being all home builders will profit greatly by looking at all the ways professional conversions were designed because they are well thought out, safe, reliable, and user friendly.
Quote from: DKO on June 26, 2014, 04:59:56 AMMy roof airs are 13.5 Duo Therm Penguin's by Dometic. I added them in 2009 and removed the original Cruise Air units. ...
Thanks for all the data, Davy. I was going to ask about 12V vs 24V, whether AGM, etc. but you've covered it all. Sounds like a good solid setup -- a good $$$olid $$$etup, but nobody said that this bussin' stuff was cheap! You obviously have a flexible system and I'm convinced that flexibility with bus systems is a real high priority -- otherwise, an owner is being dictated as to what he can do by his system.
Quote from: Lostranger on June 26, 2014, 03:44:07 AM... You know, you're not really gonna be happy until you buy a wrecked Gillig and slip the engine and drive train under your Daimler. Who knows, in the process, you might even lower it enough to be able to paint the roof.
Oh, that would be going overboard in a big way and anyone who knows me can tell you that I
never do that! (PS - The bus I bought is an '03 low-floor Gillig, ASC 8.3, B400R, "highway" rear end. Everything from the rear tires to the belt pulley on the end of the engine is on a "subframe" and it looks like that subframe will fit right onto my chassis. The powertrain is longer than what I have now but in doing the new engine mounts, I'll just move the rear bumper further back. As I mentioned before, the entire powertrain looks to be about 1500-1600 pounds lighter. Gonna be a huge job but it *will* be sweet when it's done.) ;) ;D
I am sure enjoying this thread! I am nowhere near starting on the solar part of our conversion, but I have learned a lot from this website:
http://handybobsolar.wordpress.com/ (http://handybobsolar.wordpress.com/)
We have two mini-splits that draw 8.9 amps each @ 117 VAC max.
Our genny for now is gas, but now you guys have me looking at diesel auxiliary power units. Maybe I could set one up without compressor or heater to just run a couple of alternators.
Quote from: bevans6 on June 24, 2014, 02:48:54 AM
My generator can't be run OTR, it's a little air cooled inverter-generator and it would overheat. Lots of ways to win with this deal.
Brian
Brian:
Our genny is also air-cooled. We added a grate in the floor from a local metal recycler, and a double fan unit off a Chrysler minivan radiator to the genny compartment, with a reversible switch. When parked, it sucks from the floor and exhausts out the side. Driving down the road it intakes through the side and exhausts out the floor.
Quote from: Mex-Busnut on June 26, 2014, 06:43:43 AMBrian:
Our genny is also air-cooled. We added a grate in the floor from a local metal recycler, and a double fan unit off a Chrysler minivan radiator to the genny compartment, with a reversible switch. When parked, it sucks from the floor and exhausts out the side. Driving down the road it intakes through the side and exhausts out the floor.
Dr. Steve, do you have a way (cylinder head temp, etc.) to measure the heat. I'm thinking that if you can make one work at your latitude and altitude, you've been *very* successful!
Quote from: Mex-Busnut on June 26, 2014, 06:34:38 AM
I am sure enjoying this thread! I am nowhere near starting on the solar part of our conversion, but I have learned a lot from this website:
http://handybobsolar.wordpress.com/ (http://handybobsolar.wordpress.com/)
We have two mini-splits that draw 8.9 amps each @ 117 VAC max.
Our genny for now is gas, but now you guys have me looking at diesel auxiliary power units. Maybe I could set one up without compressor or heater to just run a couple of alternators.
You could probably hook up just about anything belt driven you wanted to one, but here's the next can of worms (I have a shelf full)...
Many people could also do the reverse... which is to say that A/C compressors and heat exchangers could be mounted to generators.
Of course this depends on the generator, and if there's space for fabricating brackets and such. Sadly, my genset is too compact to fit anything additional except an external heat exchanger (which you should be able to plumb into almost anything water cooled).
I just wanted to seed that notion in everyone's head though.
(Edited to elaborate)...
Let me explain just a little further...
One could go to the junkyard and pull say... a GMC Safari minivan A/C system (or whatever) and if there was room, fabricate a means to install the compressor to their generator and build a box for the cooling unit into a cabinet or something....etc.
Pre-made systems can often be found on tractors and heavy equipment as well, which have roof or interior mounted cooling units (think about the road crew bulldozer in AZ...he's running one)..etc.
They even make 12/24vdc air conditioning for heavy equipment... looks pretty similar to our roof top units. Draws a lot of DC amps, but so does that inverter when doing the same thing.
Cheers!
Quote from: Audiomaker on June 26, 2014, 09:04:57 AM
You could probably hook up just about anything belt driven you wanted to one, but here's the next can of worms (I have a shelf full)...
Many people could also do the reverse... which is to say that A/C compressors and heat exchangers could be mounted to generators.
Of course this depends on the generator, and if there's space for fabricating brackets and such. Sadly, my genset is too compact to fit anything additional except an external heat exchanger (which you should be able to plumb into almost anything water cooled).
I just wanted to seed that notion in everyone's head though.
(Edited to elaborate)...
Let me explain just a little further...
One could go to the junkyard and pull say... a GMC Safari minivan A/C system (or whatever) and if there was room, fabricate a means to install the compressor to their generator and build a box for the cooling unit into a cabinet or something....etc.
Pre-made systems can often be found on tractors and heavy equipment as well, which have roof or interior mounted cooling units (think about the road crew bulldozer in AZ...he's running one)..etc.
They even make 12/24vdc air conditioning for heavy equipment... looks pretty similar to our roof top units. Draws a lot of DC amps, but so does that inverter when doing the same thing. Cheers!
Yeah, that's like what I mentioned above. Of course, you could always run a suitably-sized compressor off the bus engine but then you'd only have the "mechanical" air conditioning when the engine was running.
One of the companies that makes the kind of air conditioning equipment you're talking about (tractors and heavy equipment) is Red Dot. Their components are supposed to be very high quality but they're breath-takingly expensive.
If you wanted to get super tricky, you could have an engine mounted compressor and an evap unit, then have your aux unit compressor plumbed to an additional evap unit stacked on top of the first -- a single blower (or set of blowers) would pull air through the combined stack. You'd get cold from the engine evaporator going down the road and cold from the aux unit evaporator parked. And to really throw lots of $$$ at it, you could add a couple of rooftoppers to run off shore power. Cool whenever you wanted, any way you wanted.
Quote from: Oonrahnjay on June 26, 2014, 06:05:50 AM
The bus I bought is an '03 low-floor Gillig, ASC 8.3, B400R, "highway" rear end. Everything from the rear tires to the belt pulley on the end of the engine is on a "subframe" and it looks like that subframe will fit right onto my chassis....
Bruce, I'm so happy for you that I'm almost tearing up. Congratulations! Are you doing the work in Charlotte? I'd love to volunteer a day helping with that install. Seriously. Let me know when you need another set of hands.
And the rest of you guys, keep the great info coming. I love hearing how others have set up their electrics, and I love the fact that several of you are interested in solar. (Not you, Bruce, you don't even have room for stick-on panels.)
Jim in NC
Quote from: Oonrahnjay on June 26, 2014, 09:33:59 AM
Yeah, that's like what I mentioned above. Of course, you could always run a suitably-sized compressor off the bus engine but then you'd only have the "mechanical" air conditioning when the engine was running.
One of the companies that makes the kind of air conditioning equipment you're talking about (tractors and heavy equipment) is Red Dot. Their components are supposed to be very high quality but they're breath-takingly expensive.
If you wanted to get super tricky, you could have an engine mounted compressor and an evap unit, then have your aux unit compressor plumbed to an additional evap unit stacked on top of the first -- a single blower (or set of blowers) would pull air through the combined stack. You'd get cold from the engine evaporator going down the road and cold from the aux unit evaporator parked. And to really throw lots of $$$ at it, you could add a couple of rooftoppers to run off shore power. Cool whenever you wanted, any way you wanted.
I have pondered this setup that you speak of myself, but in my head it was plumbing the additional compressor from a generator or APU directly inline with the coach engine's compressor. I don't know if you can "series" compressors, but the idea would be to have your auxiliary unit run the factory air with the prime mover off.
Red Dot... ah yes... that's the idea.
All of this stuff is prohibitively expensive for most of us. It becomes a used bargain hunt.
Here's another to take a lot at the #'s:
http://www.dcairco.com/index.php/products/trucks/dc-13000 (http://www.dcairco.com/index.php/products/trucks/dc-13000)
Quote from: Audiomaker on June 26, 2014, 09:44:29 AMI have pondered this setup that you speak of myself, but in my head it was plumbing the additional compressor from a generator or APU directly inline with the coach engine's compressor. ...
I asked that question of Mr. L. Welch of Welsh vehicle air conditioning ( http://www.welchindustries.com/ (http://www.welchindustries.com/) ) in Georgia. He told me no, that the "stacked" evaporator layout was about the only usable way to provide multi-source air conditioning. What compressor is on your truck? On buses, there is a HUGE, I mean Big Honkin, air conditioning compressor. Charter (or Greyhound or???) buses want to be able to take a bus that's sat in the Texas sun all day and make it comfortable in just a few moments; plus, you'll have nearly 60 sweaty people on board and they put out lots of heat. So, Lamar told me that a smart way to go -- if you want to go an engine driven compressor -- is to put a reasonably sized car-type compressor on the engine and use that. It will have way less capacity than OEM bus systems but for a dash system or a single point in the living quarters, it should be sufficient. Of course, if you wanted to go that way, you could also install a big enough alternator but you're talking a large capacity alternator (if one isn't already on your engine).
Quote from: Oonrahnjay on June 26, 2014, 01:37:57 PM
I asked that question of Mr. L. Welch of Welsh vehicle air conditioning ( http://www.welchindustries.com/ (http://www.welchindustries.com/) ) in Georgia. He told me no, that the "stacked" evaporator layout was about the only usable way to provide multi-source air conditioning. What compressor is on your truck? On buses, there is a HUGE, I mean Big Honkin, air conditioning compressor. Charter (or Greyhound or???) buses want to be able to take a bus that's sat in the Texas sun all day and make it comfortable in just a few moments; plus, you'll have nearly 60 sweaty people on board and they put out lots of heat. So, Lamar told me that a smart way to go -- if you want to go an engine driven compressor -- is to put a reasonably sized car-type compressor on the engine and use that. It will have way less capacity than OEM bus systems but for a dash system or a single point in the living quarters, it should be sufficient. Of course, if you wanted to go that way, you could also install a big enough alternator but you're talking a large capacity alternator (if one isn't already on your engine).
Well my truck (if you've seen it) is a whole 'nuther ball of wax. It was designed to carry a large generator *and* tow an even larger generator at the same time. We'll talking about running in the 40+kw range at least.
For this reason, two large HVAC's hang off the back end (3ph 240 @ 30amp each), plus a 120 roof model. The cab was originally separated from the work area, so it just has a small engine compressor and what I would call a "wall wart" blower unit.
It's because of this that I'm curious about busses... because I don't have one to look for the answers.
I would have thought it was just as you said... that they had enormous A/C capacity from the engine because of their intended duty.
Audiomaker,
I don't know how much capacity your engine driven "small" A/C has but normally automotive A/C units are sized for fast cool down and actually have enough cooling capacity to cool a small house -- the difference being the house has good insulation and cool down cycle from none is measured in hours not minutes. How much insulation does your truck have now ?
edward
Quote from: shelled on June 26, 2014, 10:27:52 PM
Audiomaker,
I don't know how much capacity your engine driven "small" A/C has but normally automotive A/C units are sized for fast cool down and actually have enough cooling capacity to cool a small house -- the difference being the house has good insulation and cool down cycle from none is measured in hours not minutes. How much insulation does your truck have now ?
edward
Hmmm... best guess... 2-3000lbs of lead.
Regarding solar... My plan is to immediately carry a couple of portable panels for charging while I'm parked somewhere, and eventually install some hard-mounted ones to the roof. Since I've been building from the ground up, I'm just trying to get the basic things functioning and will add extra goodies in the future. My bus still had seats in it when I got it. I probably should have designed it that way from the beginning, but it just wasn't where my head was at. I love the way technology for our needs is progressing. When I started my project 5 years ago LED's were hardly to the point of serious consideration. Now the technology has improved to the point where I can't imagine going any other way. The same with inverters and solar. It's a pretty cool time to be designing and building a house on wheels. BTW, If 5 years seems like a lot of time to be building, I suppose it is, but I have a full-time job and am doing everything by myself on an island where practically everything has to be special ordered and delivered. We've been taking it places and enjoying it along the way, so it hasn't been bad. As long as it's done by December 1, 2016 I'll be happy. That's my retirement date.
Quote from: Debo on June 27, 2014, 04:11:57 AM
Regarding solar... My plan is to immediately carry a couple of portable panels for charging while I'm parked somewhere, and eventually install some hard-mounted ones to the roof.
Good plan. Solar was the first thing I did on the conversion, but we were living exclusively on a generator at the time. Circumstances alter priorities.
QuoteIf 5 years seems like a lot of time to be building, I suppose it is....
Doesn't seem bad to me. I worked on our old bus the entire ten years we owned it, and it wasn't nearly finished at the end. As long as you're happy with the progress, who else matters? I can see the allure of being able to throw full time and a small fortune at a conversion, but the "organic evolution" method has its advantages. If I was mostly done now, it would be difficult to go back and retrofit for the APU I've recently decided to use in place of a generator. Adding coils, radiators and related lines will not involve tearing out existing interior. Believe me.
Best of luck finishing by retirement day.
Jim
On the bumpy end of NC
Two quick opinions here...
1. Even though less efficient, those "peel-n-stick" PV panels sure seem like the ticket for the rounded bus tops.
2. LED lighting...great stuff, but in my home I've always kept partial incandescent. Why? Because incandescent lights are dual purpose. They make light *and heat*. Coming into summer might not be the best time to discuss this, but I've had several discussions in the past with some pretty knowledgeable folks.
The point I eventually got across to them was that LED's don't save you squat during times of the year when your heater runs because the heater has to work just that much longer to get to the set thermostat temp'.
In thermodynamics, it's all about heat transfer and management. RV's are a really fun exercise in this. Incandescent lights are really effective heat wasters, but really, aren't there times of the year when you wouldn't mind a couple hundred watts of multi-source heating with the side benefit of mood improving light during the darker times of year (and...at *night*).
An in-the-know RV'er might have a set of LED's that gets swapped in the first time the A/C gets turned on for the year, and a set of incandescents for the first day of furnace :)
Quote from: Audiomaker on June 27, 2014, 08:35:12 AM
Two quick opinions here...
1. Even though less efficient, those "peel-n-stick" PV panels sure seem like the ticket for the rounded bus tops.
Don't waste your money and time with flexible PV panels. They degrade after only a few months of continuous use, and after a year or two they're essentially useless. Use real PV panels from a reputable manufacturer, either poly or multi doesn't make much difference, and build the correct mounts for them. Do it right, and you'll have reliable power for several decades.
A rounded bus roof, like my Crown has, actually is a benefit in that it allows one to have the panels down against the roof at close to their ideal summer angle (at least, for SoCal and similar latitudes!), and there's more air space under the panels to help air circulate and keep them cooler.
John
Quote from: Iceni John on June 27, 2014, 12:54:27 PM
Don't waste your money and time with flexible PV panels. They degrade after only a few months of continuous use, and after a year or two they're essentially useless. <snip>
John
That's good to know!