Good mornong everyone-- the weather has finally started to warm up,spring is finally on its way. With so many drastic weather changes happening lately (snow& ice storms) resulting in power outages we have decided a standby generator to protect my home investment would be a good investment. I am going to remove my Honda 6500 (converted to propane) from bus and replace with a diesel generator. What would be choice of other as far as make? Are air cooled units even worth considering? The useable space on my unit MCI-5B is small 24Hx24W X32L. Maybe other have found a reliable quiet generator that will fit in space. Fuel tank not needed and to move muffler and air filter to different location easy enough to do.Wanting something in 7000 watt (larger OK). Looking for what other have done and choices they have made with good and bad results. Thanks
Larry B
Hi Larry, good question, Im looking for my 5A too, lvmci...
I am generally a fan of units powered by Kubota engines. I have had good reliability out of them, and they are fuel-sippers. However, you have some serious space constraints. I don't recall the dimensions on my current V1405-powered 20kw (inline four), but I think the engine alone would take up most of your room. (My engine is connected to the generator head by a large lovejoy coupling; if you found one that would mate up directly to the engine flywheel through an SAE standard housing or something like that, it would save you 6-8" of length.) You could obviously get away with a smaller unit, maybe even a 2- or 3-cylinder if you only need 7kw.
As for air cooled units, I don't see how you could move enough air inside of a bay or a quietbox to cool the engine enough. Even moving down the road, you would have to do some scooping and ducting. While parked I think it would be a recipe for problems. Plus, the air-cooled diesels have a reputation for being much louder than more expensive water-cooled units -- just what I hear, since I have never owned one. Others may have actual experience to offer.
Cheers, John
Simple-if you live on the left coast, Wrico International in Eugene, Or. If you live on the other coast, Powertech in Florida. http://powertech.myshopify.com/ (http://powertech.myshopify.com/) Check out the CD8000SI of Powertech. It is 34.5L x 25w x 19h. It has a layed over 3 cylinder Kubota, brushless generator, radiator air is ejected out the bottom with a squirrel cage blower. I had a friend that had one in his big rig truck. When he sold the truck, it had over 23,000hrs on it with only one gen head replacement (he had an older version that had brushes). Good Luck, TomC
The APU from trucks are becoming more available at truck wrecking yards now they are a 6500W unit but run at 2600 rpm, the the used light towers have nice quite 5 to 6.5 generators those can be had at a good buy also
Air cooled diesels are impossible to live with due to noise & proper cooling. For the water cooled, The Kubota & Perkins have great reputations, the Isuzu has not enjoyed the same. Agree the Power Tech of Florida has good choices from about 3.5 kw up, have their 12 kw w/ 4 cylinder Kubota, very dependable, smooth & quiet. Stay with a 1800 rpm direct drive, your ahead of the game.
Been an Onan dealer over 40 yrs. In the RV market, do not like their present choices. They are unbeatable in the larger models.
Cheers
Dave M
We have a Martin Diesel Generator and I had the chance to go by their shop over the summer (Independence, Ohio), have it serviced and got a chance to walk around the shop and talk to the guys there. They do some quality work. Its a smaller company and might cost a few more dollars but I think you'll get a great product and support. Wrico is awesome as well. The smaller companies do a better job at building quality equipment.
-Sean
We installed a 9kw in our MCI102A3 from engine Power Source.
http://www.enginepowersource.com/9-20kw-mobile-diesel-power-generator.html (http://www.enginepowersource.com/9-20kw-mobile-diesel-power-generator.html)
Quote from: luvrbus on March 13, 2014, 07:43:03 AM
The APU from trucks are becoming more available at truck wrecking yards now they are a 6500W unit but run at 2600 rpm
I have thought about picking up one of those APU units from a wrecked truck to power a one-room off-grid cabin. Don't some of them offer air and heat as well as power? A couple hundred very well-insulated square feet probably wouldn't be any harder to heat and cool than a truck cab sitting in the sun or snow.
Sorry for the thread detour, but that's an interesting thought...
Cheers, John
Hi Larry,
Power Tech Southeast has a very compact diesel at 8kw and 1800rpm that will fit in your space.
We installed one in a race trailer 6 months ago.
Check it out
http://powertech.myshopify.com/pages/cd8000si (http://powertech.myshopify.com/pages/cd8000si)
Nick-
Most of the generators from the smaller outfits are just peel and stick all the components are off the shelf some get out of the box with the control boards and I mean control they design their so one has to buy from them.
Wrico just buys the head and engine and a few more parts his 6.5 is identical to the Wacker light plant which at sales can be bought from a rental outfit cheap I bought a few a couple of years back one was new that was wrecked I paid 900 bucks for it not 8000 bucks
Powertech has an even shorter generator set available. It is the PT8000 with remote radiator setup. On the attached drawing, the expansion tank that sticks up can also be remote mounted (I know, I did it on my 10kw Powertech remote). Attached is a drawing-looks like it should fit. Your looking at about $7k new. Good Luck, TomC
Beware some light plant heads are wired for 220 only, other can be rewired for 120 V. high amp output, but not all can be bonded Ground and the Neutral. I seen some that just will not work in a RV with bonding.
Bruce
Oh yes, the China models & european use 220 volt ac, and not reconnectable to our 120 VAC.
As usual, beware of the bargin, sometimes you get bit.
We have found the most dependable control for these RV type generators, is the DynaGen ES52, very durable and like most things just not idiot proof.
We retro fit them to all sizes of generators, from the very small to a 12V-71 Ex AT&T genset, they work great. .Power Tech uses that control unit, wish Oban did too. So guess what we do to them ?
Dave M
Are those 50 cycles for china and europe at 220? Tom, couldnt open your diagram, lvmci...
Have seen different setups, 220 V at 50 Hz, 220 V at 60 hz, 410V at 50 hz, the reason we seem to get crazy setups, some of the off shore equipment is designed around 50 hz and 1 or 3 phase anywhere from 220 V up to the 410 area, the 410V 3 Phase 50 Hz is used for some goofy tennis court finishing. No clue and have redirected that outfit to seek service elsewhere, they use worn out Honda 2 cylinder belt drive setup, no end to the sloppy junk, and they do not seem to want to fix it proper, just fix for now. WOW, not my class of work.
TomC's diagram of the Power Tech works fine for me.
Dave M
I Have the EPS 12 k now 5 years. And is great has not stop one time. Picked mine in Charlotte NC and they made the shroud for the fan.
thanks everyone---great info. with a big list of good possibilities. That is exactly what I was looking for. I need to get busy and find a unit at a fair price. I stopped at Kabota dealer on way to shop--$9000.00 for 11000 watt. Going to do a little more looking , maybe find a used unit with low hours for less money. Will check out truck wrecker yards now knowing what might be a possibility. Will remove old Honda generator tomorrow and put back in serice with gas tank and carb. I also have some wiring to finish for new inverter. Trying to get every thing ready for a trip to east coast this summer. Thanks
Larry B
We have a 5C with a Kohler 3 cylinder Diesel 15KW water cooled in the old compressor bay behind the front wheel.
Dave5Cs
PO put a 4kw Onan Propane generator in the engine compartment on the passenger side of my 5A. My propane tanks are built in and hold about 25 gallons total. It was noisy, could drain my tanks quickly if i used it much, and blocked access to that side of the engine. We only used it once or twice a year so when it started acting up last year i yanked it out and sold it cheap. Was going to buy 2 Honda 2000s and the parallel cable but could only afford one at the time and have used it twice so far when dry camping. We don't use the ac when going down the road so we don't need a larger generator.
Quote from: wg4t50 on March 13, 2014, 01:42:58 PM
We have found the most dependable control for these RV type generators, is the DynaGen ES52, very durable and like most things just not idiot proof.
We retro fit them to all sizes of generators, from the very small to a 12V-71 Ex AT&T genset, they work great. .Power Tech uses that control unit, wish Oban did too. So guess what we do to them ?
Dave M
Dave - do these control units have an auto start/stop? Can they be configured to run an older non RV style generator? My old generator (from the 90s) has an on/off 'run/kill' switch and a start switch. So its a 2 step process to start it up. Am thinking about ways to possibly have it autostart/stop based on a voltage meter and a relay but can't quite figure it out. Maybe 2 relays/sensors are needed - one for the run / kill and one to start it.
Sorry if I hijacked....
-Sean
Fulltiming somewhere in the USA
1984 Eagle 10S
www.herdofturtles.org (http://www.herdofturtles.org)
Tried to attach the ES52 Manual, too big so lost the entire posting.
Try again,
You only need a wire for start solenoid, low oil press, hi water temp, fuel pump/solenoid, battery then the two wire for start/stop. Very simple, just keep a clear head when adjusting the 20 turn pots for timing/sensing, very easy if you can read and understand. The unit is pretty tuff, but not idiot proof, my favorite expression, "some can destroy an anvil with a feather" ;D
Would search for the DynaGen ES52 manual or I can Email it with an address.
Dave M
I have a Universal brand 12KW that I took out my bus before I sold it. It has 2000 hrs on it and runs and works great. If interested give me a call @ eight zero one 391 9214 Kent
Quote from: Seangie on March 14, 2014, 04:54:40 AM
Dave - do these control units have an auto start/stop? Can they be configured to run an older non RV style generator? My old generator (from the 90s) has an on/off 'run/kill' switch and a start switch. So its a 2 step process to start it up. Am thinking about ways to possibly have it autostart/stop based on a voltage meter and a relay but can't quite figure it out. Maybe 2 relays/sensors are needed - one for the run / kill and one to start it.
Sorry if I hijacked....
-Sean
Fulltiming somewhere in the USA
1984 Eagle 10S
www.herdofturtles.org (http://www.herdofturtles.org)
Interested to see what you rig up Sean. I'm wanting auto start/power loss sensing. Come home one too many times to find the power out in our bus and our fridge thawed. Messy, expensive, annoying
Sent from my iPhone using Tapatalk. Clumsy fingers may contribute to mistakes.
Very interesting Sean & Scott, an electronic guru would have to pipe in about this, I would think it would have to be a relay that would stay open with 110 AC while the generator is operating, when it loses power, the circut would close, allowing 12 volt DC immediatly to starter, but on a timer if the gen didn't start within a given time, inorder to not continually run the starter if no fuel or a problem, all on a master kill if you were on a power pole, the hotels have a system for the casinos like this with massive generators, but its all 220 AC. it would be great if it was all on a chip without mechanical relays, sounds like a great idea, maybe the people who make the surge protectors have something up their sleeves, lvmci...
www.fwmurphy.com (http://www.fwmurphy.com) they have made the auto starts for generators for a long time
good luck
Ems-gc10, impressive, thanks Clifford, tom...
Quote from: Scott Bennett on March 16, 2014, 05:26:56 AM
Interested to see what you rig up Sean. I'm wanting auto start/power loss sensing. Come home one too many times to find the power out in our bus and our fridge thawed. Messy, expensive, annoying
I would be very nervous about the reliability of auto start when I was away for more than a few hours. Whether I used auto start or not, I would opt for an alarm system that could call my phone in the event of a malfunction.
Here is one from a quick search:
http://www.homedepot.com/p/Mace-Wireless-Home-Security-System-80355/100654450 (http://www.homedepot.com/p/Mace-Wireless-Home-Security-System-80355/100654450)
Dave M, is self starting a concern, have you run across any issues with self starting gensets? Lvmci...
Quote from: Seangie on March 14, 2014, 04:54:40 AM
Dave - do these control units have an auto start/stop? Can they be configured to run an older non RV style generator? My old generator (from the 90s) has an on/off 'run/kill' switch and a start switch. So its a 2 step process to start it up. Am thinking about ways to possibly have it autostart/stop based on a voltage meter and a relay but can't quite figure it out. Maybe 2 relays/sensors are needed - one for the run / kill and one to start it.
Sorry if I hijacked....
-Sean
Fulltiming somewhere in the USA
1984 Eagle 10S
www.herdofturtles.org (http://www.herdofturtles.org)
Sean, you might take a look at Magnum's auto generator start. They have two models - one that interfaces with their inverters and another that is standalone (http://magnumenergy.com/auto-generator-start-stand-alone-me-ags-s/).
Of most interest are their sample wiring diagrams for generators (http://magnumenergy.com/ags-to-generator-wiring-diagrams/). You might find a diagram that fits your generator setup.
-Kitt
'77 Eagle Model 05
I had an Onan Marquis air cooled gas generator in my MCI that was quiet as a mouse and very reliable. Very happy with it. The Wanderlodge came with a Kohler 12.5KW diesel water cooled that was very noisy. It died & I replaced it with a diesel 12KW air cooled Onan. It was on a fire truck. I bought it from the junk yard for $600. It had 650 hours on it. It runs fine, does the job with zero problems, & is not any louder that the old Kohler. I also like not having to fool with a radiator & antifreeze. I ran it last summer under about 80% load (3 X 14KBTU A/Cs, electric water heater, electric frig, & misc loads) & it ran fine & didn't overheat at all.
That's why they make chocolate & vanilla........ It's all according to what you like! ;D ;D
TOM
Hi Kitt, looks like the product that they use in Marathon Prevost conversions, lvmci...
The reason I would want auto start is that we just visited Big Bend National park and they don't have hookups in the main campground. On top of that genny hours were from 8am until 8pm. I often found ourselves having to decide what time of day we had to leave or be back by to start up the generator to run for 2hrs to charge the batteries. Kind of a pain as we would have liked to have left before 10am each morning and have been back after 6 each night.
Quote from: Kitt on March 17, 2014, 04:49:09 AM
Sean, you might take a look at Magnum's auto generator start. They have two models - one that interfaces with their inverters and another that is standalone (http://magnumenergy.com/auto-generator-start-stand-alone-me-ags-s/).
Kitt - that's exactly what I am looking for. Love that it has a quiet time setting. Thanks for this.
Quote from: Len SilvaI would be very nervous about the reliability of auto start when I was away for more than a few hours. Whether I used auto start or not, I would opt for an alarm system that could call my phone in the event of a malfunction.
Len - most of these auto starts/controllers have a generator fault setting that I am sure you could rig up to that alarm system. It would be a nice touch. Although we had little to no cell coverage and no wifi when were in Big Bend.
Quote from: wg4t50Would search for the DynaGen ES52 manual or I can Email it with an address.
Dave - I looked at this. That is a great controller with many features. I would love to replace my current control board with that. I think it still needed a signal from another device to auto start though. The magnum controller above has that capability and they even have a diagram on the magnum website to wire to a ES52.
Thanks guys. This is awesome stuff. And Larry - again...sorry that I hijacked your thread (just a little bit).
-Sean
Fulltiming somewhere in the USA
1984 Eagle 10S
www.herdofturtles.org (http://www.herdofturtles.org)
Many configurations available including thermostat signal to start the genset to run the A/C and yes the DynaGen ES52 controller is a very popular control unit.
Have installed many, mostly to upgrade older out of production and parts no longer available.
Also they work great on diesel, glow plugs, gas engines, gasoline or vapor and electronic or mechanical governors.
Dave M
Quote from: Len Silva on March 16, 2014, 07:13:04 AM
http://www.homedepot.com/p/Mace-Wireless-Home-Security-System-80355/100654450 (http://www.homedepot.com/p/Mace-Wireless-Home-Security-System-80355/100654450)
The web page specifically says this requires a land line. I assume only the sensors themselves are wireless.
There are a number of power outage alarms that send alerts via cellular, but they seem to cost $200 and up.
Quote from: belfert on March 17, 2014, 08:24:25 AM
The web page specifically says this requires a land line. I assume only the sensors themselves are wireless.
There are a number of power outage alarms that send alerts via cellular, but they seem to cost $200 and up.
My bad! When all else fails, read the instructions.
Been looking for a voltage sensitive monitoring relay device to start the generator at 12.2VDC and run for a preset time, think the basic sensor would be this one, then would need to add a time delay opening relay to stop the genset when the battery was full charged. Anyway take a look.
Dave M
http://atkinsonelectronics.com/manufacturing/product_pdfs/VRDC-40A.pdf (http://atkinsonelectronics.com/manufacturing/product_pdfs/VRDC-40A.pdf)
My Setup came with the DynaGen BCM (Battery Cotrol Monitor), however they no longer produce it (Rats) Has been doing a great job.
Quote from: Len Silva on March 16, 2014, 07:13:04 AM
I would be very nervous about the reliability of auto start when I was away for more than a few hours. Whether I used auto start or not, I would opt for an alarm system that could call my phone in the event of a malfunction.
Here is one from a quick search:
http://www.homedepot.com/p/Mace-Wireless-Home-Security-System-80355/100654450 (http://www.homedepot.com/p/Mace-Wireless-Home-Security-System-80355/100654450)
Buy a good auto start, then you don't have to worry. I have used the GSCM products for years and have never had a problem. They have dedicated wiring setups for Outback inverter/chargers too, which makes for ease of setup. If you diesel generator has a safety shutdown system, which I think most good ones do, what's to worry about. I have left mine for weeks on end and have never had a problem.
Quote from: wg4t50 on March 17, 2014, 05:27:10 PM... take a look. Dave M
http://atkinsonelectronics.com/manufacturing/product_pdfs/VRDC-40A.pdf (http://atkinsonelectronics.com/manufacturing/product_pdfs/VRDC-40A.pdf)
If I read the price list right, that one is about $90, this one (simpler but looks good) is $70.
My Foretravel has the DynaGen DC voltage monitor, have it adjusted to start the genset at 12.2 VDC, it runs for 2.5hours, that seems to be correct when I had the 8g8d Gel batteries, now have 4 of them, but very little experience with what run time is correct.
DyanGen no longer makes he DC voltage sensor, I was able to down load the manual before they took it off the list.
Dave M
Quote from: Oonrahnjay on June 03, 2014, 01:52:50 PM
If I read the price list right, that one is about $90, this one (simpler but looks good) is $70.
That is the company that makes the auto gen starts that I have had good luck with. Seems they cost a lot more than 90 bucks tho. The ones I get are fully adjustable and start diesels, many auto starts don't due to the glow plugs. Very good support also. Before you buy call and talk to a tech, they won't try to oversell you but will explain exactly what their product does.
Maybe I am missing something (very likely),it looks like there is no adjustable time delay for run time once the low voltage has been triggered,
My setup triggers on at 12.2 volts DC, and keeps the generator running for 2.5 hours, all these setting are adjustable. The Xantrex has a few charge rates, but starts off at 100 amp charge, and in the 2.5 hour run time, it drops back to about 10 amps.
Just glad I do not need one at this time as the DyanGen voltage sensor is doing great (so far).
Dave M
Larry,
The space you have is going to limit your options. Power Tech (especially the CD 7000) is about the closest I know of at 34" long, and you would need it to be open at the right end (looking at it installed) for air flow to the radiator.
It would just fit your 32" if you ran a remote radiator (which I actually prefer if you can find a location for it).
If I read it correctly, you are going to stick with your Honda for a bit, but down the road you might consider one of these.
A remote radiator setup can be very useful since it is easy to tap the water line with heat exchangers for water or air heating (My CD puts out enough heat to warm the entire rig if it weren't being blasted out into the atmosphere).
Aside from that, as others have mentioned, the APU from a big rig may be your best bet if you are limited to that amount of space.
They also have the advantage of having built in A/C compressors so if you get one complete with the in-cab amenities, you can cool your rig with one at less cost per BTU than an electric A/C.
The truckers know what they're doing here.
I for one will probably install an APU next to my Power Tech. I like smaller (but still commercial) generators that don't waste so much fuel at low loads, and supplement this with a good inverter (and perhaps solar) setup.
I will probably look for an APU that also carries a Kubota in it. I've been pleased with mine (currently running 18hrs/day for over 2 months having over 5000hrs on it already).
Anyway, if I had the space to work with that you do, it would be a Powertech CD with remote radiator, or the APU from a big rig.
All the Best
I am installing a 12kw Wrico Genset into my truck. It is only 36" long and uses a 3cylinder Kubota. It uses a 13kw head, but Dick Wright derated it to 12kw because of the engine.
With Diesel engines, there is very little difference in running a small engine or a large engine fuel wise (for instance, you can get just about the same fuel mileage in a truck with a 350hp as with a 600hp-if driven the same). I would NOT use another APU in addition to the Diesel genset-just a waste of space and weight. Good Luck, TomC
Quote from: TomC on June 08, 2014, 09:19:15 PM
I am installing a 12kw Wrico Genset into my truck. It is only 36" long and uses a 3cylinder Kubota. It uses a 13kw head, but Dick Wright derated it to 12kw because of the engine.
With Diesel engines, there is very little difference in running a small engine or a large engine fuel wise (for instance, you can get just about the same fuel mileage in a truck with a 350hp as with a 600hp-if driven the same). I would NOT use another APU in addition to the Diesel genset-just a waste of space and weight. Good Luck, TomC
That's an interesting take Tom.
I would agree that they are not linear but the smaller one's do use less fuel for small loads (ie...running at minimum throttle).
The Power Tech spec's for the genny I own (CD7000) compared to the slightly larger CD8000 (905 and 1105 Kubotas respectively) do show a difference in no load / quarter / half / full between the two, and you are correct... it's not a lot but it's there.
Personally I wanted the smallest commercial generator that I could find as I'm mostly charging batteries with it and I'm trying to do the ultra-green/solar/inverter thing.
For people who are considering boon docking as I am (or the option really), and extra gallon a day might matter.
I have been off grid for over a month now and am in fact typing this from a diesel powered computer and internet connection.
That generator is about as critical as things get for me at least until i can afford some solar up top.
Because of this, and because my generator has been running for the last 20hrs mostly powering maybe 1kw out of it's 7kw potential, I would prefer myself to have one even smaller if I could (but still commercial, and still diesel).
The APU's fill this gap and I think they can supply 5k or so on their 2cyl Kubotas...Perkins..or whatever.
So for the weight, and actual usage, I think you could get a small genset and an APU for about what a 10 or 12k weighs...at least in the ballpark and have not only redundancy of a critical system, but the option to run A/C and other acc's that APUs come with directly instead of running a larger generator to do so.
Setup correctly with battery and inverter power, you get security and efficiency.
At least that's how I calculate it.
My rig had a generator compartment set up for a 30kw set. I skipped this in favor of the 7kw stuffed in a smaller compartment, and I think I still have room for a used APU when $ allows.
Cheers!
Sean
Here's the chart I have between a 7kw and 8kw (both 3cyl Kubotas)
(https://busconversionmagazine.com/forum/proxy.php?request=http%3A%2F%2Fimg.photobucket.com%2Falbums%2Fv500%2Ftwomarbles%2Fconsumption.jpg&hash=c7a09cd9f139632adec748d57378d7dfb4515709)
For the 1kw difference in output power, it's averaging about .08 gallons per hour difference.
Run 12hrs/day, that's a gallon per day, or in my case 1/3 of my fuel tank capacity in a month.
Many APU's burn about .10 gallons/hr while powering your small loads and running their own A/C units (or heat from the heat exchanger).
That's close to the *difference* between the 7kw and 8kw if I'm reading it right.
So I suppose it's dependent on what one wishes to do. The big one for RV's seems to be running 2 or more air conditioners (usually 3) at once.
I can only run 1 of my 3, so for me it's get on the grid in the summer or sweat, but when not running those A/C units, I might be saving over $100/mo running lights, computers, and charging batteries (which will power the microwaves and tools and such).
Add 250lbs of APU and I get one more A/C only when I need it, perhaps use it most of the time over my 7kw, and have a backup.
Does that logic follow?
I am only throwing out there what makes sense to me because I'm new at this (RV'ing), and I'd love to double check my thoughts.
:)
This is not accurate, and you're not following my line of thought. If you only want to creat 2kw worth of power, either an APU or a 8kw genset will create that. The only difference in the fuel burn is the amount of fuel necessary to power the larger engine-which on a Diesel is very small. Even running the APU instead of the genset, I doubt you'd see much more then a quart or 2 daily in fuel burn. You'd have to put on thousands of hours to make up the difference in the about $10k price for the APU.
What I could see is a home made single cylinder air cooled Diesel belt driving a 200 amp 12v alternator to keep your batteries up. 200amps @ 14.1volts equals 2820 watts (4hp engine to power)-or enough to power an inverter without battery drain. Good Luck, TomC
Quote from: TomC on June 09, 2014, 12:04:31 PM... What I could see is a home made single cylinder air cooled Diesel belt driving a 200 amp 12v alternator to keep your batteries up. 200amps @ 14.1volts equals 2820 watts (4hp engine to power)-or enough to power an inverter without battery drain. Good Luck, TomC
I understand what you're saying here, Tom, but what would you expect for mechanical losses generating and electrical losses inverting? As a ball park, I'd guess about 10% for each. So if your little engine could make enough power to actually drive the alternator enough to make 200 amps, that would make actual, usable electrical power at a roof-top air conditioner at about 2200 watts (or roughly 18 Amps @ 120V). Is it practical to start and run a rooftop A/C at 18Amps in "real life"?
I'm not saying that your principle is wrong, but I'm thinking that a theoretical 200A at 12V is going to be pretty close to the bone in real-life -- meaning more engine, more alternator, more inverter would be needed (if my guess about the practical amount of current needed is correct). And that would up the fuel consumption and reduce the "marginal" fuel cost saving.
What do you think? BH NC USA
TomC,
I do not think you would enjoy a single cylinder 1800 rpm diesel air cooled, they are very noisey as in big noise, Onan had a great single cylinder diesel,r 3 kw, burnt .32 gal per hour at full load, great, they ran for ever, the issue was the noise & vibration, not having a water jacket sure produced noise.
The noise was the demise of them.
Dave M
Quote from: TomC on June 09, 2014, 12:04:31 PM
This is not accurate, and you're not following my line of thought. If you only want to creat 2kw worth of power, either an APU or a 8kw genset will create that. The only difference in the fuel burn is the amount of fuel necessary to power the larger engine-which on a Diesel is very small. Even running the APU instead of the genset, I doubt you'd see much more then a quart or 2 daily in fuel burn. You'd have to put on thousands of hours to make up the difference in the about $10k price for the APU.
What I could see is a home made single cylinder air cooled Diesel belt driving a 200 amp 12v alternator to keep your batteries up. 200amps @ 14.1volts equals 2820 watts (4hp engine to power)-or enough to power an inverter without battery drain. Good Luck, TomC
I guess I'm missing your line of thinking Tom, but we'll get it straight :)
I'm not sure what you are saying is inaccurate? The chart I posted is right out of my Power Tech manual.
I would agree with you to an extent that fuel burned = kw generated. For the most part it is just mechanical losses from moving the larger engine parts. Still, there comes a point of whatever is required to maintain the 1800rpm at idle (or at loads requiring only idle).
The generators in the Queen Mary would require gallons per hour to power a single 100w light bulb, vs less than a gallon per day for a smaller generator doing the same thing. There is no questioning that larger machines cost more to run even under the same load... so where is the crossover point?
Comparing a 5, 7, 10, or 15kw generator, it might only come out to a gallon a day difference, but that also doesn't account for increased emissions, often noisier, and higher maintenance costs.
Take for instance my 7kw. With generators, you are supposed to change the oil every 100 hours (every 5 days continuous).
My generator requires exactly 1 gallon of oil....weekly @ $30. If it required 2 gallons per week, I just ate $120/mo extra without considering the fuel difference, cost of larger (or more) replacement parts...overhaul cost...and an additional couple hundred pounds of weight without adding any redundancy to the system.
I've really looked at my generator usage. I've lived off grid a few times in my life for 3 months or more, and usually the only thing I can find that requires 10kw+ is A/C and heat. Almost everything else...either in a home, or RV, can be powered without about 5kw. That includes hair dryers and such if on a rated inverter system, so only A/C, and heat (water too) are requiring more since they run full time.
Of course, this all comes from my own frame of reference. Maybe most buses have electric clothes dryers and such? I'm ignorant here.
What I do know is that an inverter doesn't require me to put oil in it every week.
These days truckers live on the road for weeks, and most of the guys doing it are using APU's. Whether it's hype or not, most APU manufactures quote about an 80% difference in fuel consumption vs idling the prime mover. Some of the numbers you see on idling semi's is in in the range of 1 to 1.5 gallons (per hour) with A/C running and such, and these are waaay more advanced engines that what you will find in any generator (computerized efi...etc)... they've got laptops hooked to the things figuring out how to save a gallon, but still they use 8 times what the little APU does to allow the trucker to camp at the Travel America.
I also agree with you that a $10k APU isn't for everyone, but neither is a $10k Onan Quiet Diesel. Both units are pretty expensive new.
My wallet buys used, so I see APU's in the $1k to $2k range... which is less, or around the same as a decent used diesel generator.
Hypothetically (and I mean to test this), a smaller generator like my own, combined with an APU and an inverter system might run the 2-3 air conditioners that a 10kw generator would, but be cheaper to run during the other 3 seasons since you could pick and choose as required.
Heck, If I could design my own rig, and it's compartments, I'd probably line up 3 identical APU's side by side... each with it's own A/C compressor (going to 3 different areas), each with it's own heat exchanger (one to heat air, one to heat the block, and one to heat water), and each with it's own generator head or 48v alternator.
I think that would be a very versatile system as you could have your AGS start and stop them as required automatically, and talk about security in redundancy...yay!
I suppose we all have our own thoughts on this, and I don't mean to hijack this thread any further, but the OP's request included a 32" compartment, and I guess that's how we got on the APU topic in the first place. I can't think of much else diesel that could be made to fit in there.
:)
I realize using a 1 cylinder air cooled would sound like hitting a hammer on a steel plate. The better choice is a Kubota (or any other manufacture) smallest 2 cylinder water cooled.
Powering a 2800 inverter at 14.1vdc takes about 200amps. You don't have to worry about starting an A/C since a typical 2800watt inverter will have over 5000watts of surge power-that can be drawn from the batteries. Remember, you just want an alternator that keeps the batteries up, and a 200amp will do that. Good Luck, TomC