24 to 12 volt conversion

[tcolley]

Has anyone here converted there coach from 24 volts to 12 volts? I'm purchasing an MC7 in a couple weeks and this is something I've thought about doing. Other than swapping the starter, alternator, light bulbs, and rewiring the batteries and headlights from series to parallel, is there anything else I need to be aware of? Will all of the existing wiring work with 12 volts?

[Melbo]

Just a thought here.

When you halve the volts you double the amps.

Amps determine wire size.

There are a LOT of wires in the bus that run front to back

Do some good electrical math before you get into a rats nest.

Melbo

[sledhead]

the other big + in having 24 v 's is you can use a 24 v inverter so less d c amps to get to the 120 v ac side

dave

[bevans6]

My thought is that 24 volt is by far the preferred solution compared to 12v for a bus.  We need some high power every once in a while, and the higher the voltage the better.  If I had a 12 volt bus I would be looking at ways to convert as much as possible to 24 volt.

Brian

[luvrbus]

I don't know about that one Brian,Eagle was always 12 volt and they were easy  and with GM only a couple of models were ever 24v everything about a 12 system is cheaper and easy to find

[daddyoften]

I have a 12v bus and I'm glad about the simplicity of the 12v but I'm trying to figure out a way to run 24v for a better inverter.

And yes about the wire size! This could very well cause you a problem. Your wire size will be generally too small for the higher amperage demand now.
Eric

Sent from my XT1254 using Tapatalk

[gumpy]

Has anyone here converted there coach from 24 volts to 12 volts? I'm purchasing an MC7 in a couple weeks and this is something I've thought about doing. Other than swapping the starter, alternator, light bulbs, and rewiring the batteries and headlights from series to parallel, is there anything else I need to be aware of? Will all of the existing wiring work with 12 volts?

Why?

There's a reason the engineers at MCI installed a 24v system in that bus, and all their other buses. Granted, some of the high loads like heating and AC might go away as a personal
conversion, but you still have many other loads to deal with.

The existing wires, in general, will be too small to handle the 12v loads on similar devices.

Yes, it can be done, but it sounds from your question like you don't really understand what's entailed. That can be a dangerous thing.

My suggestion, if you want a 12v bus, buy one that was designed to use 12v.

[TomC]

The main reason for 24v was for running the two big A/C blowers. Although my transit is 12v and had two big blowers also. Here in the US, virtually all big rig trucks are 12v with many buses also. European trucks and buses are mostly 24v. I prefer the ease of 12v since all cars are 12v.
But converting a 24v bus to 12v you have to watch the amp draw vs wire size since amps are doubled at 12v compared to 24v. Good Luck, TomC

[TedCalvert]

Good Morning, ye  frosty Bus Nuts.  0 degrees here in SE Ohio.

My '86 Prevost, ex-seated, was all 24 volt.  It has a converter for the 12 volt radio/PA.  I believe the headlamps are 12V, connected in series from 24v.

I have replaced front, side and rear markers with 12v LED, and temporarily re-connected the feed for the markers from a 12v tap from the battery bank, which is present in the front electrical compartment.  For now, I used the existing 24v feeds to the side turn-signals, through 3-pin regulators, to feed the 12v LED side turn-signals.  I will eventually change all exterior lighting to LED; it may all draw enough current at 12v to require a Vanner equalizer but  more likely I'll just re-use the aforementioned convertor.  I'm not to that bridge yet!  I'll probably use HID headlamps, as LEDs are still very expensive.  I'll definitely need a 12v source for them, unless I can find some that will run on 10-30 volt input. 

I will definitely keep the 24v starter.  Engine gauges too.  No DDEC.

As for the house system, I expect to have all 12v LEDs.  Only a small inverter for the 'fridge.  Heat, cool, cook: run the gen-set.  But I agree with the previous comments as to wire size.  24v inverters might be more common, and therefore cheaper too.  I'll only need a small one.  For those who need whole-house inverters, I think Bob Glines used a 48v bank and inverter.

I'm an old electrician, so this part is fun for me.  Other aspects of the conversion process, maybe not quite so much.

Open to feedback.  Stay warm.

[Lin]

I'm going to guess that the reason you want to change everything to 12v is for the simplicity of having one voltage system rather than two.  If that is the case, I would point out that those that have 24v and 12v systems get used to it quickly, and it really does not create any confusion.  In theory, you would almost need to change every wire that you converted from 24v to 12v.  As said earlier, if you must have an all 12v bus, start with one that was built that way.

[zimmysurprise]

TC- worked through the same decision tree you are climbing now. I decided to keep my 24v GMC 24v mostly because of the cost of conversion and the chance that an undersized wire somewhere decided to melt down and burn up my investment. Here are a couple things you should know about 24v:
-Accessories do draw less amps with the system you have
-Inverting to 120v A/C is easier
-24v lights and motors are common in military vehicles and on the other side of the ocean
-Many LEDs are suitable for use in 12v or 24v systems
-24v to 12v knock downs are cheap and plentiful on the internet (to power refrigerators, GPS, etc.)

And in the word of Homer Simpson- "Oh look, they have the internet on computers now"

[bigred]

I have a CC Prevost conversion that is a Hybrid 12/24v System.What a mess!! Even with all the literature that I have ,you are still not sure what runs what unless you check the voltage .The side marker lights,clearance lights  ,and curb lights are 24v .The headlights and tail and turn signal lamps are 12v.The dash gages and lights run off the House 12v system. With out a doubt the most asinine thing I have ran into.The way they did this was to use four coach battery and two Vanner isolaters .If you running a two stroke,I would definitely keep the starter 24v as those things are not the easiest things to start especially in cold weather.   

[Lin]

Bigred, my statement that the two voltage system will not be confusing assumed that the builder would not purposely make it confusing.  On mine, everything coach is 24v and everything house is 12v (except 120v, of course).  Therefore that is never really a question.