So I understand this coach I am looking to buy is a 24v system, can I replace the 2 24v batteries with 12v or is the 24v a requirement because of the size of the engine/coach itself?
Or is it simply use 24v for the coach side and then ad 12v for the RV side?
The batteries are 2- 12 volt, wired in series to produce 24 volts.
So for the chassis side use 12v with good cca to start and then deep cycle with high amp hours for the RV side.
Gonna have to start to figure out AC and refrigerator requirements here soon...
I'm setting up a house battery bank on a 4108, which is a 24v system. My bus has two 12v start batteries wired in series to make 24v. If your system is the same, then yes, you would use two appropriately sized 12v batteries for your start batteries.
For your house batteries you have choices to make. I'm going with a 12v system and will be using four L16 six volt deep cycle batteries wired in series/parallel to provide 12v output. The same four batteries can be wired to provide 24v. The choice really depends on how you intend to use the power downstream. Your choice of 12v or 24v for your house system will also determine how you charge the house batteries and whether you can (easily) charge them from the bus alternator.
This has been discussed .... often. So start out by using the search function. There's reasons to stay with a 24 volt house bank and there's reasons not to. Only you can decide which side of that divide you will land on. After you have used the search function for a while you may wish to come back and ask more questions but for now you'll learn more quicker with some searches.
I suppose it might help us to know what the bus is you are looking at.
In general, if it's a 24v system, it was designed that way for a reason, and would be difficult and expensive to change it to a 12v system.
As for the house system, you will have to decide which way you want to go. As already said, there are pros and cons for each voltage on the house system.
Ok first, thanks search was helpful but I think I have more questions than before. :)
So I am looking at a 1978 MCI8, it appears to be full 24v lights etc.
I had assumed that if the bus we built with 24v that changing ould be difficult but in some of the posts I noticed people saying 24v bulbs and accessories were hard to come by too.
I dont THINK changing the entire chassis side bus/wiring to accommodate a 12v system is in my future but is it hard to find 24v LED lights or appliances, etc or do people just create another "leg" in their electrical system just for 12v? There is hardware needed for that conversion yes?
Quote from: PNWorBUST72 on February 15, 2018, 04:16:52 PM
Ok first, thanks search was helpful but I think I have more questions than before. :)
So I am looking at a 1978 MCI8, it appears to be full 24v lights etc.
I had assumed that if the bus we built with 24v that changing ould be difficult but in some of the posts I noticed people saying 24v bulbs and accessories were hard to come by too.
I dont THINK changing the entire chassis side bus/wiring to accommodate a 12v system is in my future but is it hard to find 24v LED lights or appliances, etc or do people just create another "leg" in their electrical system just for 12v? There is hardware needed for that conversion yes?
simply put, the 24v system, as it is for the existing systems, as designed when new...cannot/should not be changed to 12v....(it could be but would cost a small fortune)
the house system, IF an inverter is in your future, can be either 24v or 12v. your choice, BUT, again, more cost effective to "keep it 24v" if that is what is the current chassis system is..
First, yes, a 78 MC8 is 24v bus system and the headlights were 24v. They are hard to find, and expensive. It is possible to change the headlights to 12v bulbs, running in series on the 24v system. MCI came out with a modification sheet explaining how to do it. All other lights (clearance, turn signals, tail, brake) can also be converted to 12v, and LEDs are readily available. You just have to know how to get your 12v without endangering the 24v battery. An equalizer would be the first thing to look at.
Keep in mind that a 10w bulb on a 12v system will draw twice the amps as a 10w bulb will on a 24v system. Wiring gauge is sized according to the amps being drawn through it, so it's important to keep in mind the size of wiring for any circuits you plan to convert from 24v to 12v. If you go from incandescent 24v to LED 12v I imagine that the current draw would be reduced, but it's something to pay attention to.
There are a few great threads on how to get 12v from a 24v system. It needs to be done correctly to keep the draw & charge on the batteries even, hence the reason many people use an equalizer to accomplish things. I decided to go with a 24v to 12v battery-to-battery charger, something which seems controversial to some but will work for us.
What I'm trying to say is that there are many ways to do this which will work well. Explore some of the marine suppliers as well as the RV suppliers to see more 24v appliances.
Well my thought here was to keep anything 24v on the bus as OEM, 24v.
But to add a 12v system for the interior lights/switches/appliances.
It seems that the issue is how to keep the 24v chassis batteries and the 12v coach batteries charged correctly?
Before you choose a voltage for the house...
What do you want to accomplish?
Your order of decision is wrong.
What is this "interior lights/switches/appliances" stuff you speak of?
That's far far from enough information to ignore the 6000+ watt alternator on the coach...
We try NOT to blindly duplicate the foolishness in stick and staple RV's in our bus conversions...
Happy coaching!
Buswarrior
If you do decide to tap 12V off the 24v chassis batteries to run something, be careful how you do it. The po of our rig had tapped one of the two batteries to supply 12V to several things and the brand new 8D batteries that he included the day we bought the rig were giving us grief only 8 months later. I did verify proper alternator output and good connections, ground and water levels. It turns out that the batteries he replaced were hardly more than a year old as well.
Without a equalizer, the alternator supplies equal juice to both batteries, continually creating a uneven charge between the two batteries, thus apparently leading to their early death.
We replaced the batteries and installed one of these https://www.amazon.com/gp/product/B01LYK6G2Y/ref=oh_aui_detailpage_o01_s00?ie=UTF8&psc=1 (https://www.amazon.com/gp/product/B01LYK6G2Y/ref=oh_aui_detailpage_o01_s00?ie=UTF8&psc=1) to obtain 12V from across both batteries, thus solving the problem.
You may not need a 40 amp unit (other sizes are available at less cost), we were using this to run a military grade electric heater for windshield defrosting and needed the extra juice.
Forgot to add that the unit in the link was way, way, way, cheaper than the equalizer, which also would have been another way to address the problem.
I was planning, before the 24v detail I missed took us South, to add a bank of 12v batteries on the Coach side to run but not sure thats viable anymore.
My goal here was to run 12v all through the coach for lights, charging ports, 12v RV appliances, leaving the Chassis side as is at 24v. But other then the obvious 12 vs 24 I dont understand the differences that would impact that system.
I am looking at this and it seem 24v on BOTH sides is the best option:
http://jdfinley.com/electrical-system-design/ (http://jdfinley.com/electrical-system-design/)
with a 24v house system and a 24v/110v inverter, using 110v LED lighting you will be far better off than trying to "have 12v interior systems"
at least that's what i'd do.
I would also have one combined battery bank. which I do.
Quote from: PNWorBUST72 on February 15, 2018, 08:58:14 PM
http://jdfinley.com/electrical-system-design/ (http://jdfinley.com/electrical-system-design/)
are you boondocking...
is solar in the cards....
the example on that link is over engineered. And unnecessarily complicated...
I.M.O.
We want to boondock but the overall electrical design/needs of the bus will help dictate that at first. I dont have 10k to spend in batteries and panels.
Solar is a for sure yes, next phase of the build.
Electrical, in case its not obvious, is still hard for me to follow sometimes, but I am trying. Thanks to all for your help.
In my conversion I have 8 agm batteries with a Magnum 4024 inverter, in my interior I have some ac items, refrigerator, 3 built in electric wall heaters, microwave, a full gas stove with oven, 2 Samsung smart TV's, Splendid combo washer dryer, air compressor, electric 20gal water heater. So you can see some items will need 120/220 ac. Except for 2 ac lights that my wife really wanted all my other lighting is either 12 or 24v dc. My 12v dc tap if used with a Vanner equalizer. For charging the batteries up it is shore power or generator, solar someday. Have had no problem so far keeping the refrigerator running while driving to destinations off the invertor. My 2 ac lights have led bulbs so the ac draw is less. 12V items are easy the find 24V a little harder but if you search you can usually find something. I didn't want to tap too much 12v so I tried to find more 24v items.
Quote from: PNWorBUST72 on February 15, 2018, 08:58:14 PM... I am looking at this and it seem 24v on BOTH sides is the best option: http://jdfinley.com/electrical-system-design/ (http://jdfinley.com/electrical-system-design/)
Yes, but ... You say "lights and charging ports, etc." It harder to find those kinds of items in 24V. Lights are available but a much smaller range of wattage, color, etc. If you have 12V, you can use 12V "thimble" chargers for USB chargers but I don't think I've seen such a thing in 24V. I think that for interior devices, you need either 12V or 120V.
I agree with Eagle's comments, too. Keep it simple, but if you want real electrical capability, you will need batteries and an inverter.
It might help to change your terms:. The batteries for the starter in a bus conversion are called the "start" batteries, the batteries for the RV stuff are called the "house" batteries. Sometimes the batteries are both.
For my conversion, I kept the 24v starter, and made a 12v RV system. Two alternators, 12v and 24v. Two 12v batteries in series for starting, four golf cart batteries for the 12v system. Most of the MC 7-8 run two alternators like I do.
For those recommending a 120v system for most appliances (which will be run through an inverter), I don't understand how it's more efficient.
My 12v DC fridge draws about 2 amps DC. An AC fridge, even one that draws only 2 amps, will actually draw much more from the batteries since making 2 amps AC will require 20+ amps DC.
I see lots of people going with the residential fridge units, so I assume that I'm missing something.
Quote from: richard5933 on February 16, 2018, 07:46:56 AMFor those recommending a 120v system for most appliances (which will be run through an inverter), I don't understand how it's more efficient.
My 12v DC fridge draws about 2 amps DC. An AC fridge, even one that draws only 2 amps, will actually draw much more from the batteries since making 2 amps AC will require 20+ amps DC.
I see lots of people going with the residential fridge units, so I assume that I'm missing something.
Calculate in watts and you'll see what you're missing.
Quote from: richard5933 on February 16, 2018, 07:46:56 AM
For those recommending a 120v system for most appliances (which will be run through an inverter), I don't understand how it's more efficient.
My 12v DC fridge draws about 2 amps DC. An AC fridge, even one that draws only 2 amps, will actually draw much more from the batteries since making 2 amps AC will require 20+ amps DC.
I see lots of people going with the residential fridge units, so I assume that I'm missing something.
since when is a conversion efficient ? isn't that a classic oxymoron ?
if you aren't boondocking then a good inverter has a pass thru that does not eat battery wattage.
the OP needs to express or determine his intent.
my need for inverter supported output is from point a to point b or short term, (say 7-10 days or less off the pole. I am all electric. no propane).
it matters, and we are all just speculating.
A regular house refrigerator costs to buy versus a DC or propane refrigerator costs to buy...?
I can buy the batteries necessary and then some, with the difference.
As noted, efficiency in a bus conversion???
Only of the cheque book?
And poorly on that too...
happy coaching!
buswarrior
Quote from: richard5933 on February 16, 2018, 07:46:56 AM
For those recommending a 120v system for most appliances (which will be run through an inverter), I don't understand how it's more efficient.
My 12v DC fridge draws about 2 amps DC. An AC fridge, even one that draws only 2 amps, will actually draw much more from the batteries since making 2 amps AC will require 20+ amps DC.
I see lots of people going with the residential fridge units, so I assume that I'm missing something.
Not a chance this is accurate if its actually running on DC. Maybe it draws 2 amps @ 12 volts while running on propane but there's zero chance it draws that running on 12 volts.
Absorption fridges are notoriously inefficient so that may make a case for inverting up to 110 but the other option would be a 12 volt compressor fridge. Either way, its going to draw significantly more than 2 amps @ 12 volts while its running.
I am taking about 12v compressor units, not absorption. I don't have specifics on my fridge since it's older, but I've seen stats on new units between 2-5 amps depending on size. Even if it's twice that, it is still less than a residential fridge would pull from the batteries through the inverter.
I like my beer COLD. RV refers suck-- not cold enough, and ice cream isn't frozen. Plus you have to vent them out the roof, cost too much new, and are too small. I never heard of 12v RV reefers without also having propane (I know, Summit, but are they for boats?).
He probably has this one or an older version.
http://www.thetford.com/product/de-0061ev-0061/ (http://www.thetford.com/product/de-0061ev-0061/)
Well, eBay had two. $1300.+, and 1800.+. 7 cu ft.
I paid $299 for my stainless steel Sanyo and it is 10.3 cu ft. They are just hard to find in SS. Costco is the place to buy them when available, I've seen prices double than that on line.
at 7 c feet that is small for a fridge
most people see the low price for a home style fridge compared to a r/v fridge price and with all the fires from some r/v style fridges I can see the change to a home style fridge
but yes you will pay the power price from a home style fridge
Dave
The bus we are looking at has an older residential fridge but we could be willing to go propane if the electrical needs where too much.
I would like to be able to run the fridge, AC and maybe a TV and some lights while we drive.
I am down for doing the JD route and get all the bells and whistles but I would prefer to do it in logical stages for a cost perspective.
It's a toss up. You pay now, or you pay later.
I chose to go residential 120v fridge. 11 cf. $300. However, I have $1100 of Trojan batteries and a 4000 watt sine wave inverter that I got a deal on at $1200. I also have a 7.5WK generator. My house bank is 24v and I charge it off the big 50DN alternator while driving. I can run the house a/c off the inverter if necessary while driving, though it doesn't compete to the bus a/c when it's working properly. That's what I wanted, and I'm very happy with how that has all worked.
Quote from: Geoff on February 16, 2018, 03:15:38 PM
I like my beer COLD. RV refers suck-- not cold enough, and ice cream isn't frozen. Plus you have to vent them out the roof, cost too much new, and are too small. I never heard of 12v RV reefers without also having propane (I know, Summit, but are they for boats?).
Both of our coaches had/have 12v/120v Norcold refrigerators (without propane). They use 12v DC compressors. Both kept ice cream frozen and beer cold, and they both were able to run for quite a while without using much from the batteries. A few different manufacturers make them, and they're more common on boats than RVs, but they can be found in RVs. Apparently Custom Coach was fond of them back when they were in business. Personally, I would not have a propane fridge in my bus for any reason. The danger people see from RV fridges are the propane units - the 12v compressor fridges don't seem to have a problem with fires like the propane ones.
For just two of us we don't really have need for a huge refrigerator. It's not like we're trying to stock up for a week or more at a time. We had 7 cu ft in our first coach, and it easily held enough for the two of us. I think our current one has only about 5.5 cu ft. It's just about as small as I would consider useful. If we were going to be on an extended trip away from stores I'd probably look into adding a small 12v chest style cooler in the basement for added storage.
If price is a factor, then it's absolutely going to be the residential units that win the contest. But then you've got to add enough batteries and charging capacity to run them.
Guess it's all in what one considers better suited to his/her needs. Luckily there are enough options for us to be able to have this conversation.
Quote from: bobofthenorth on February 16, 2018, 02:10:37 PMNot a chance this is accurate if its actually running on DC. Maybe it draws 2 amps @ 12 volts while running on propane but there's zero chance it draws that running on 12 volts.
Absorption fridges are notoriously inefficient so that may make a case for inverting up to 110 but the other option would be a 12 volt compressor fridge. Either way, its going to draw significantly more than 2 amps @ 12 volts while its running.
An issue with refrigerators is that they aren't "steady draw" like a light bulb. They use more power in hotter conditions, if they have unchilled food put in, when they're drawing down at startup, if the door is opened more often, etc. At a steady average run, my NovaKool is rated at 48 - 50 watts; that's about 4 Amps at 12V (nominal) or about .4 Amps at 120V. It's an energy sipper, works great in the fridge and has a powerful freezer, and was breathtakingly expensive.
I can tell you how my 10.3 cu ft works out. I have four golf cart batteries. The Trace inverter jumps between 1&2 amps draw @120v. The batteries will keep the reefer going for about 2.5 days before the Trace shuts down to save the batteries. I could set up the Trace to automatically start, but haven't felt the need.
Quote from: Geoff on February 17, 2018, 08:23:30 AM
I can tell you how my 10.3 cu ft works out. I have four golf cart batteries. The Trace inverter jumps between 1&2 amps draw @120v. The batteries will keep the reefer going for about 2.5 days before the Trace shuts down to save the batteries. I could set up the Trace to automatically start, but haven't felt the need.
Is that the draw on the 120v side? If so, how much is it actually pulling from the batteries in 12v?
If it's only pulling that low of a reading on 12v, then you're doing really well.
Quote from: richard5933 on February 17, 2018, 08:47:17 AM
Is that the draw on the 120v side? If so, how much is it actually pulling from the batteries in 12v?
If it's only pulling that low of a reading on 12v, then you're doing really well.
Watts - Watts - Watts! If it's pulling 1-2 Amps at 120V, that's 120 - 240 Watts. At 12V, that would be 10 - 20 Amps. But instantaneous readings don't tell you much about refrigerators. If a fridge is cooling down, it will use more power (it will run almost continuously until it reaches thermostat setting). Then, it will come on as the thermostat calls for it and goes off when the thermostat thinks it's cool enough. To get a good idea of how many days a fridge will run before the batteries go to "low voltage", you would need to get an average of wattage use over time. A single point in time tells you either nothing or very little.
Quote from: Oonrahnjay on February 17, 2018, 09:08:53 AM
Watts - Watts - Watts! If it's pulling 1-2 Amps at 120V, that's 120 - 240 Watts. At 12V, that would be 10 - 20 Amps. But instantaneous readings don't tell you much about refrigerators. If a fridge is cooling down, it will use more power (it will run almost continuously until it reaches thermostat setting). Then, it will come on as the thermostat calls for it and goes off when the thermostat thinks it's cool enough. To get a good idea of how many days a fridge will run before the batteries go to "low voltage", you would need to get an average of wattage use over time. A single point in time tells you either nothing or very little.
I'm not sure why you're talking about watts. Watts is just a calculation of volts x amps. Not sure what it has to do with this conversation. 1-2 amps at 120v is 10-20 amps at 12v, in round numbers. That's my point. When you pull amps from a battery bank to power the inverter at a higher rate than you do to power the DC fridge directly you'll run out of juice faster.
For an inverter to make the AC power it's pulling DC power. It sounds like such a little bit when said as 1-2 amps, but if the inverter is pulling 10-20 from the battery bank then it's using more than if he here doing it with a 12v compressor only pulling 2-5 amps.
I understand about the power cycle thing on a fridge. That is the exact same whether a DC or AC powered fridge. The concept of thermostats and such works no differently on my DC fridge than it would on a fridge powered by AC.
I think that bottom line is this... There is a loss to heat when power is converted from DC to AC. This is why inverters have cooling fans. There is simply no way around this. There is also a loss just having the inverter turned on. Also no way around this. I'd love for you to show me the math of how to make a 120v fridge last as long on a battery of a set size as a 12v DC fridge pulling fewer amps.
All that said, I understand that for some people the residential fridge works for them. Great. For us, I'll stick with the energy-sipping 12v compressor fridge. It works for us. There is no right answer as to which one someone should choose.
This thread is a mess.
The reason to use watts in a discussion like this, is so we are comparing properly.
So, a busnut might say "my DC refrigerator uses 450 watts when it is running flat out"
Another might say "my dollar store bar fridge uses 500 watts when running and using a kill-o-watt device, it uses 4 kwh a day averaged over a 3 day test, door closed."
Another busnut with engineering knowledge and some fancy test tools will chime in with "that new pure sine wave inverter I got off ebay that everyone thought was crap, turns out it runs at 94% efficieny!"
There is supposed to be a difference between a moderated board and Facebook...?
Happy coaching!
Buswarrior
I'm not sure why this is a mess. Some manufacturers list their specs as amps, some as watts. Use the formula below however you need to make the comparison.
The formula is pretty straightforward.
watts/volts=amps
Since most people rate their battery banks in available amp hours, for me doing the calculations in amps makes more sense.
I just looked at the Norcold site. For a brand new 7 cu ft. fridge it uses 0.4 amps on 120v and 3.2 amps on 12v. If you run an inverter to make the 120v you'd be using approximately 4 amps to run this fridge. The difference between the 3.2 and the 4 amps would mostly be the energy loss to the inverter itself. This is a very efficient fridge whether on AC or DC.
Compare that with a residential fridge and you will see why I lean towards this type of fridge. Let's say that you have a residential unit that uses 'only' 1-2 amps. That's still 2 to 4 times the power consumption of the RV model.
If someone wants to make this comparison using watts instead of amps, the formula above can make that easy. Regardless, the end result will be the same.
All that said, if someone wants or needs the larger residential fridge and has the ability to make it work for them, then that's what they should do. I'm only stating what works for me, and that's the smaller more efficient unit.
Ok, not trying to get into a amp vs watts argument because I doubt I understand a 1/3 of it...
We want to run AC(thinking roof mounts but the noise is a question), maybe 2 maxxfans (at least one for the shower/bathroom area), 2 27in-ish TV's, propane tankless hot water heater, propane RV oven, smaller fridge(7-10cu ft - most likely residential), assorted lighting of course, USB charge ports, maybe a Playstation 4.
Can I run the 24v starter batteries like normal and just build out the rest of the coach side as a standard RV, 12v and 110v? As long as I dont try to use the 24v alternator to charge my 12v batteries OR dont draw anything from the 24v side, I can built them as completely separate systems no?
I only need an isolator if I plan on drawing from both sides of the system correct?
Quote from: PNWorBUST72 on February 18, 2018, 09:28:44 AM
Ok, not trying to get into a amp vs watts argument because I doubt I understand a 1/3 of it...
We want to run AC(thinking roof mounts but the noise is a question), maybe 2 maxxfans (at least one for the shower/bathroom area), 2 27in-ish TV's, propane tankless hot water heater, propane RV oven, smaller fridge(7-10cu ft - most likely residential), assorted lighting of course, USB charge ports, maybe a Playstation 4.
Can I run the 24v starter batteries like normal and just build out the rest of the coach side as a standard RV, 12v and 110v? As long as I dont try to use the 24v alternator to charge my 12v batteries OR dont draw anything from the 24v side, I can built them as completely separate systems no?
I only need an isolator if I plan on drawing from both sides of the system correct?
You can certainly have them as two totally separate systems. The problem would be trying to figure out how to charge the batteries while on the road, since you'd only be able to charge while plugged in or while running the generator. If you pulled up anchor in the morning after drawing down your batteries overnight, you'd arrive at your next campsite at the end of the day with uncharged house batteries unless you ran your gennie while driving.
Couple of quite definitions:
An equalizer is used to pull 12v from a 24v battery bank. It pulls from both batteries evenly so you don't end up with one being overcharged and one being undercharged. It is possible to just tap into the point between the two 12v batteries in a 24v battery bank to get 12v without an equalizer, but this will quickly destroy your batteries.
An isolator is different. This is used to charge two separate battery banks from one charging source while keeping the two sources isolated from one another. They do this with diodes usually. For example, if you had a 12v start system and a 12v house system you could use the engine's alternator to charge both battery banks while driving. The isolator is there to keep the house system from drawing down the start batteries while camping. It basically make for a one-way pathway from the charging source to the batteries. On our 4106 we used a solenoid instead of an isolator with a manual switch to bridge both the house batteries and start batteries together while driving down the road. This allowed us to use the bus engine's alternator to charge the house batteries. When we shut down the engine we flipped the switch and disconnected the two battery banks from each other. The isolator allows them to stay physically connected but provides an electronic barrier instead.
If you went with a 24v house system (using a bank of deep cycle batteries separate from your start batteries) then you can easily charge them while on the road using the bus alternator by using an isolator or a solenoid. If you did this and had a 24v house system, then you would need to use an equalizer or 24v-to-12v converter to pull 12v for those appliances which required 12v. Probably a converter would provide enough 12v current in your case.
We went with a system like you're describing (totally separate 24v start and 12v house systems), and to charge the house batteries while on the road I'm installing a 24v-to-12v battery-to-battery charger. It will charge the house batteries at 70 amps using a 3-stage charge just like any other plug-in charger. It only charges while the alternator is operating on the bus engine so it shouldn't draw down our start batteries, plus we're adding the remote on/off switch to be certain. This battery-to-battery charger is made by Sterling. We also have a Progressive Dynamics 70-amp 120v plug-in charger for when we have power from pole or gennie. I know that our system has some duplication, but it works for us.
It looks like you'll have mainly a 120v load, so running a 24v inverter may make more sense as they can be more efficient and require lighter gauge wiring. That would be a decision you'll have to make. The remaining 12v appliances you plan to run are not high-draw items, so they could probably run from a 24v-to-12v converter.
I'm sure that others will offer other options which are equally valid. The problem is always trying to decide which will work best for you.
Great reply Richard, thanks.
So how does the equalizer get wired in?
AC Side - Shore Power/Generator > Transfer Switch > 50amp Breaker Box > Inverter > Battery Charger > Coach Side Battery Bank
DC Side Chassis - 24v Alternator > 24v Battery Bank >24v Loads
DC Side Coach - Inverter from AC Side > 12v Fuse Boxes > 12v Loads
Does multiple alternators of the same voltage charge the batteries faster or more fully? I could add a 12v alternator to change just the 12v Coach Side?
why ?
they make 24v inverters
and 24v LED's
12v makes no sense to me.
An equalizer basically monitors two strings of 12 volt batteries to be sure they are equally charged. You center tap a 24 volt battery bank for 12 volt power and the equalizer makes sure the batteries stay at equal states of charge. I absolutely would not try to run a 12 volt inverter off a 24 volt battery bank.
Yes, busnuts often add a second 12 or 24 volt alternator for the house bank. I recommend an external regulator instead of an internally regulated alternator. You can get external regulators designed for charging deep cycle battries
Quote from: eagle19952 on February 18, 2018, 11:39:08 AM
...12v makes no sense to me.
Some things used in a conversion/RV are just easier to find and source in 12v format, like a Fantastic Fan and other appliances. Correct, many of the things that we'll be using can be had in 24v formats, and even a phone charger can be made to run from them. However, try finding something like a dash radio or CB radio that is going to run out of the box on 24v and you'll have more limited selection. In my opinion, there is wisdom in having 12v circuits available, even if the house batteries are set up in a 24v format. Since it's really simple to do this it shouldn't present a problem.
To get 12v from a 24v battery bank is really quite simple. There are two ways to do it. One way is to use a 24v-to-12v converter. You just connect the input of the converter to an appropriately sized 24v DC source and you will have 12v DC available at the output. For the most part this method reduces the voltage by converting it to heat, so it's not the most efficient.
Another way to get 12v circuits available is to connect an equalizer to the 24v battery bank. Follow the instructions provided by the manufacturer of the equalizer to connect the equalizer, and it will draw the power from both batteries and not cause one to draw down more than the other. This method could be more efficient, but it is also more expensive. Here is a manual from Vanner which should provide some more information: http://www.vanner.com/manuals/EQUALIZER-60-SERIES.pdf (http://www.vanner.com/manuals/EQUALIZER-60-SERIES.pdf)
Don't confuse the equalizer with the inverter. An inverter is used to create AC power from a DC battery bank. You would use an inverter to make AC power when you are not connected to shore power or generator. Some inverters are packaged with the battery charger in the same box. How to connect them to your system will depend on what type of bells and whistles are included such as automatic transfer switch, charger, etc.
Inverters are matched to the voltage of the battery bank, so if you have a 24v battery bank you use a 24v to 120v inverter. Remember that DC amperage required to power an inverter goes up as the voltage goes down. In other words, to get the same 2000 watts AC from an inverter on 12v DC will require twice the amps as it will from 24v DC. Interters running on 24v are more efficient and require smaller connecting cables as an inverter with the same AC output would on 12v DC.
An equalizer is not the same as an inverter and is not interchangeable. Equalizers are used to pull 12v from a 24v battery bank while maintaining equal charge in all the batteries. If you tap into a 24v battery bank to pull 12v you will discharge some of the batteries but not all when running the 12v load. When your charger kicks in, it will overcharge the batteries that were not discharged and/or undercharge the ones you were drawing down.
I THINK I am more inclined to keep the systems separate, maybe adding a solar controller and a single solar panel to keep the 24v system charged...
This thread has reaffirmed to me that i have very little knowledge on electricity.
My bus came with both 12v and 24v. I removed the AC and big heater so I had no use for a large 24v system and hand grenade alternator (50DN). I went with a 12v house system. Much easier for RV stuff, and all my lighting was already 12v. I added a 180 amp 12v and a 65 amp 24v alternator. Works out great.
They like to call gear driven alternator hand grenades....yet, thousands of city and highway busses and coaches used them for millions of miles. If they were that troublesome, I'm sure they wouldn't be around that many years. Could be some weren't adjusted at the mounting adapter properly, or bearing went bad causing catastrophe. I don't know if they have a periodically servicing schedule.
Quote from: chessie4905 on February 20, 2018, 05:11:53 AM
They like to call gear driven alternator hand grenades....yet, thousands of city and highway busses and coaches used them for millions of miles. If they were that troublesome, I'm sure they wouldn't be around that many years. Could be some weren't adjusted at the mounting adapter properly, or bearing went bad causing catastrophe. I don't know if they have a periodically servicing schedule.
You just have to look at the damage the gear driven 50DN can do to be wary. It might not happen that often, but I have seen it happen, and I don't need to take the chance. There was never a day that I drove my bus with the 50DN that I didn't worry it would blow and ruin my engine. I took it off, made a steel plate to cover the hole, and breathed a sigh of relief. Big fleets can absorb the repairs, but for individuals it is a big hit.
You know, this yak yak about gear driven alternators catastrophically failing is NOT something that was discussed years ago...
So, what is it?
Peeps repeating rare things, making them common?
Peeps re-using worn parts that shouldn't be in service?
Peeps unable to identify worn/failing components?
Peeps not inspecting anything, missing the loosening fasteners, etc?
If we repeated every rare and wild failure that everyone ever heard of... nobody would dare operate their coach?
Happy coaching!
Buswarrior
Fleets pulled the 50D and serviced it every 100,000 mile to changed the bearing and the drive gears per the book,they will destroy a engine I have seen it more than I liked and they will brake a cam
I have a 8v92 here in the shop now the 50D broke the cam in, no way I want one hanging on the back but to each his own.There are photos here on this board that shows what can happen when the 50D turns loose not a pretty sight
For balanced reporting, in a Big Transit setting, back in the day, 1700 2 stroke buses, nobody even thought about an alternator locking up. Sure, they stopped charging, but with gear drive/oil cooling, bearing lubrication was assured, vs the old belt drives. They were run to failure, or engine re-build. Nothing special done. Alternators were re-built in shop, dedicated bench job, returned to spec.
Like being hit by a meteor, yes, it is possible, but likely??
So, perhaps the advice to busnuts is a reminder to pay attention to the preventive maintenance on gear driven alternators, because if allowed to get into poorly maintained or grossly negligent condition...
We need to be careful that "negligent" doesn't become "normal" and have a busnut spending money where none needs to be spent?
There's already lots of more pressing stuff to worry about in an old coach?
Happy coaching!
Buswarrior
OK but I never knew of a transit co or a top notch tour operator like Boomer that didn't service one.the only transit co I was around was Houston Metro though and they just pulled it and replaced with one from inventory and rebuilt the old one,it's not like one has special bearings all they have is a cheap @$# single row bearing inside to replace
If you have 100 coaches and one fails that's a 1% failure rate - maybe you'll live with it or maybe you won't but its a 1% failure rate. If you have one coach and your alternator takes out your gear train that's 100% failure rate and its a catastrophe.
You can't apply the same rational percentage failure based thinking that a large enterprise running a fleet of modern coaches uses when we're talking about end of life single coaches maintained by amateurs. If the potential damage at failure is catastrophic, there is no penalty for taking remedial action and the cost of that remedy is nominal then it probably makes sense even if in a commercial setting it might not be cost effective.
The last time I heard of a price to have an electrical shop rebuild a 50DN it was around a $1000. Plus getting it on and off. I don't need a 300 amp, 24v alternator. So I run belt driven alternators and never worry.
Quote from: Geoff on February 21, 2018, 05:57:53 AM
The last time I heard of a price to have an electrical shop rebuild a 50DN it was around a $1000. Plus getting it on and off. I don't need a 300 amp, 24v alternator. So I run belt driven alternators and never worry.
They are slowing going away the 24v is the only 50D you can buy parts for now even Kirks doesn't have parts for the 12v now and he said the 24v parts are getting hard to come by,a bus engine is the only place you find a gear driven 50DN
How can I tell what alternator I have? I assume there is the standard OEM one?
Where do people mount secondary 12v alternators? Pics?
Ok so 24v system with an aftermarket Vanner unit to run the 12v headlights and etc....
Do you guys justy all DIY this or do you contact local electricians to help you plan this stuff out?
The MCI the 24v coach system does drive 12v headlamps. Some have been converted, mine has a plate on the left side driver panel stating 12v lamps. Later ones I believe are factory wired for 12v. It does not seem like using a Vanner 24 to 12 is recommended for driving headlights
Later MCI's in the 1980's had a nice 12 volt headlamp solution that could be retrofitted to an older bus, or a variant used. The right hand pair of headlamps were powered from 24 volt power bus to a 12 volt center tap, and the left hand pair of headlamps were powered from the 12 volt center tap to ground. Any light could fail and the others would still work. As long as both sides were lit the batteries stayed balanced. relays were used to access the center tap and to do the high/low beam switching. No other equalization was required as long as you didn't run for weeks with only one working headlight. Conversion issues would be running new heavier gauge wiring to carry the 12 volts to the headlamps, finding and installing suitable relays (I think one more than stock was required for the conversion), but once done, done and dusted for a good long time.
Personally I ripped out and threw away an aftermarket 12 volt conversion (sold by MCI) and installed halogen lamps with 24 volt bulbs. Superior solution, used stock wiring, great light, bulbs are available on-line and I carry spares. Very happy with my solution.
Brian
Quote from: PNWorBUST72 on March 25, 2018, 10:28:57 PM
Ok so 24v system with an aftermarket Vanner unit to run the 12v headlights and etc....
Do you guys justy all DIY this or do you contact local electricians to help you plan this stuff out?
Do it yourself, or suffer the consequences?
There is no ready supply of paid help out there that is trained in designing, engineering and installing alternative systems in ancient motorcoaches.
Oh, there's lots who will pretend, and try to educate themselves, and you, on your dime...
Mechanics are trained to replace parts on vehicles designed and engineered by others, with charts, manuals, online resources, and training.
When you were a teen, who was heading to auto shop, and you want to hire them to do what?
Few come back on here and brag they wrecked their coach by paying the wrong guy...
Teach yourself by reading authoritative publications, certainly not via social media...
happy coaching!
buswarrior
I don't know if this will work for your purposes or not, but it's worked reliably and fine for mine for 4 years. Samlex makes a 24v to 12v converter that is good for up to 30 amps of 12v output. (I think mine was less than $100.) I have a 24v chassis electrical system ('81 MC9), a 120v house system on a Magnum Hybrid Inverter (24v), and a 12v - I'll call it "auxiliary" system powered by the Samlex.
I use the aux system mostly for my 12v LED lighting, and my 12v suburban furnace. I just wanted the ability to run a few 12v things if there was something I liked that was only available that way. That's the beauty of these things. You can build it any way you want to.
The typical 24 volt to 12 volt converter like the Samlex is a regulated power supply that actually puts out 12 volts exactly. The problem with using that type of converter with headlights is that headlights (and all automotive light bulbs) are designed for an automotive "12 volt" system that actually is 14 volts when the alternator is operating. That means that headlights will be significantly under voltage when powered by a true 12 volt converter.
Makes sense. Just to clarify about the Samlex, it'll accept anything from 20-32 VDC, and the output is actually 13.8 (12v nominal). May or may not work for the headlight application. Just another data point. Bus on, good people!
I have one of these:
https://www.amazon.com/Pyle-PSWNV720-Power-Converter-Technology/dp/B003P17X8I/ref=sr_1_3?ie=UTF8&qid=1522156282&sr=8-3&keywords=24+volt+to+12+volt+converter (https://www.amazon.com/Pyle-PSWNV720-Power-Converter-Technology/dp/B003P17X8I/ref=sr_1_3?ie=UTF8&qid=1522156282&sr=8-3&keywords=24+volt+to+12+volt+converter)
Used for small loads, pulse air wipers, King cruise control, electric sunshades,gps.
I also have a Vanner. This will make wiring easier for at dash items.
13.8 is perfect for automotive use. I was looking some years ago for a converter for my trailer light relay box, and only found regulated 12 volt supplies, I suspect intended for powering a computer or TV. What I went with was a 20 amp converter that is actually a small equalizer, it takes in the 24 (or 28 volts actual) volts and precisely divides it in half and outputs that. It can also work backwards and take in 12 volts and output 24 volts. It was very funny, I powered it from the rear 24 volt bus in the engine bay electrical panel. The first time I plugged in my trailer, all the rear lights started to work because the little brake battery on the trailer was connected to the 12 volt side of the converter, it turned that into 24 volts on the 24 volt bus, and my brake lights turned on!
Quote from: chessie4905 on March 27, 2018, 06:17:05 AMI have one of these:
https://www.amazon.com/Pyle-PSWNV720-Power-Converter-Technology/dp/B003P17X8I/ref=sr_1_3?ie=UTF8&qid=1522156282&sr=8-3&keywords=24+volt+to+12+volt+converter (https://www.amazon.com/Pyle-PSWNV720-Power-Converter-Technology/dp/B003P17X8I/ref=sr_1_3?ie=UTF8&qid=1522156282&sr=8-3&keywords=24+volt+to+12+volt+converter)
Used for small loads, pulse air wipers, King cruise control, electric sunshades,gps. I also have a Vanner. This will make wiring easier for at dash items.
I like this one. It appears that it puts out about 12.8V at standard conditions so it won't charge a 12V battery very well, but the user ratings show that it's reliable at the 360W Continuous that it claims and you can do a lot with 30Amps of 12V power. It's limited but the reports are that it performs well within its limits.
Quote from: Oonrahnjay on March 27, 2018, 06:26:57 AM
I like this one. It appears that it puts out about 12.8V at standard conditions so it won't charge a 12V battery very well, but the user ratings show that it's reliable at the 360W Continuous that it claims and you can do a lot with 30Amps of 12V power. It's limited but the reports are that it performs well within its limits.
from commentsat Amazon.
"I have paralled 2 and it works, however the load sharing is not equal..I'm sure this would void any warranty of course..I also increased the voltage out to 13.2v on both units by adding a trim resistor at the appropriate circuit connection..again, this will obviously void any warranty".
Could you provide a bit more information? I'm not sure what you decided in the end about coach vs. house batteries, so it's really hard to make any recommendations.
What I've gathered so far is that you've got a 24v coach system. Sounds like you're adding a 24v house battery bank. Sounds like your most recent post is trying to figure out the best way to run the 12v loads that you'll have for both the house and coach systems.
Did I get that roughly correct?
I am not sold on either option to be honest.
Having a 24v house bank that can be charged from the alt makes alot of sense. But, and I haven't looked myself much, the difficulty in finding all the lights/USB charges/ appliances that can run on 24v seems to be an issue.
For now, I am hoping to get a simple 120V system installed so I can plug in at the storage yard I am at. But I DO NOT want to have to do all this over again when I add say a genny later so planning is important.
50AMP plug, load center/circuit breaker and some romex for 1-2 outlets inside the bus basically...maybe a dedicated 15A plug since I will be using a standard outlet to start with.
Thanks for the extra information. I think that the first step would be to really think through all the items you'll have inside the bus running on electric power when things are completed. You can then work backwards from there to determine which system works best for you.
Some go with all residential appliances and devices and little or no 12v DC need. When plugged into the pole or on generator these systems are basically just a little house on wheels. When on the road, they operate the 120v system by powering an inverter from battery banks.
Others manage with all 24v DC systems. Lots of 24v DC devices and appliances are available, mainly for use in marine applications and on trucks.
Some do like we did and have a 24v chassis system and a 12v house system plus the 120v for use when on pole or generator. We also have a few 120v outlets powered by inverter to enable us to use TV, etc. while boon docking.
Which you go with really depends on your end goal. Once you have a clear end game it will be much easier to make specific recommendations.
My 8 AGM battery bank is 24v with a 4000 watt Magnum inverter for AC, 24v items run off 24v and items that I could not find 24v run off a 12v battery tap backed up by a 100 amp Vanner equalizer. The 12v/24v wires are wired into a Blue Sea Systems fuse blocks using basic automotive fuses clean and simple, each fuse block also has a volt gage next to it so I can monitor voltage. All my electrical is mounted in a cabinet in the bedroom so I can monitor everything from inside the coach. If you are not up on AC/DC electrical learn as much as you can before you tackle it. One mistake can either be fatal or cause damage to yourself or damage some expensive items. AS they say miss wire a unit and you will let the smoke out. ;D ;D
I have a 24v House and coach system, having the main engine and alternator as a backup power source and OTR power source makes so much sense. Sounds like you know this.
I use 12v for all my LED lights, USB plugs, etc. I started by just taking a wire from the middle of my 24v battery bank, but that lead to differences in charge for the 4 batteries. I looked at getting an equalizer but it was a bit expensive. I do have one on the coach side still.
Anyway I bought this little DC DC converter for much cheaper to handle all my 12v needs.
https://www.amazon.com/gp/product/B01LZJ9MGF/ref=oh_aui_detailpage_o02_s00?ie=UTF8&psc=1 (https://www.amazon.com/gp/product/B01LZJ9MGF/ref=oh_aui_detailpage_o02_s00?ie=UTF8&psc=1)
Here is a video cued up to showing how I hooked it up.
https://youtu.be/Cae8U8YB7-w?t=444 (https://youtu.be/Cae8U8YB7-w?t=444)
Below is a link to view my power consumption.
https://vrm.victronenergy.com/installation/17735/share/c7e5a8fd (https://vrm.victronenergy.com/installation/17735/share/c7e5a8fd)
I also run a normal 120v fridge, it doesn't use that much power honestly. The fridge uses maybe 700w a day (it will cycle on for 10-15 minutes every few hours). Only other draws I have is a small computer, wifi router, stereo, tv, etc. Every night I don't dip much below 80% state of charge. Save the money on an RV fridge and get one from Home Depot or something. I got my stainless steel fridge free from Craigslist, just needed the coils blown out with compressed air.
Thanks for the reply, I am a follower on your YouTube channel! :)
I THINK I have one of those equalizer from Vanner, I dont know the specs on it though. I know they converted my headlights to 12v, not sure what else.
(https://i.imgur.com/b3aQpCM.jpg)
I have that same one as well, but I figured I'd keep the coach side stock as much as possible.
I had considered pulling my house 12v from the Vanner, but didn't want to risk killing my coach starter batteries.
My hope is to have the systems decoupled as much as possible , except for the charging while underway.
So you kept the headlights/coach, etc on the vanner and used the 2nd equalizer for the other house items?
You put all the electrical i the 3rd bay on the driver's side? Where did you put your shore connections and all?