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Old 04-21-2017, 11:21 AM   #1
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'86 Chevrolet 8.2 Detroit - Charging System Wiring Diagram

Hello everyone! We are purchasing our first bus tomorrow (hopefully!) and I'm trying to get a jump on the wiring diagram for our home bank, and well just about everything else lol. Being an electrician (apprentice) I'm anxious to start drawing this all out. I'm not having any luck with google or other forums. I was hoping one of you might be able to point me towards a service manual and/or wiring diagrams. Thanks in advance!

Also, after reading through a lot of these posts I had a question. Why are a lot of you running solar power or a generator instead of bringing the existing circuit from the engine bay to a disconnect, and then to your battery bank. If you're gonna burn fuel in a generator, you might as well use the one that came in the bus. This could also be a lifesaver if you were to lose a battery in the starting system. Close that disconnect and use your home bank to start the bus in an emergency situation. Just thought I'd share and see what you more experienced electricians thought about that.
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Old 04-21-2017, 12:46 PM   #2
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Well

My apologies, I see that some people do indeed use the bus charging system to trickle charge their house battery bank. I did see that last night, my bad.

Basically just wired in a continuous duty solenoid, and make sure it's fused. Easy enough.
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Old 04-21-2017, 01:08 PM   #3
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Using the bus engine to recharge a house bank is not a very good idea.

First, it puts so little load on the engine that it tends to load up with unburned fuel which tends to wash the cylinders causing premature wear. It also fills the exhaust system with a lot of lot temperature exhaust that leaves a lot of excess soot and moisture which tends to rust and clog the exhaust system. And lastly, the bus alternator is not really designed to recharge a large house system. At low engine speeds it will be at maximum charge which is hard on the alternator and speeding the engine up just wastes fuel.

A much better choice to recharge house batteries is with a passive solar system or a genset that is designed to recharge a house battery system.
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Old 04-21-2017, 01:10 PM   #4
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there have been numerous discussions on how to charge the house batteries from the alternator. Apparently the charge still needs a charge controller to eliminate burning up either the alternator or over charging the house batteries.

Many of us are pretty weak on electrical issues.
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Old 04-21-2017, 01:49 PM   #5
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Quote:
Originally Posted by cowlitzcoach View Post
Using the bus engine to recharge a house bank is not a very good idea.

First, it puts so little load on the engine that it tends to load up with unburned fuel which tends to wash the cylinders causing premature wear.
It pulls to much voltage away from the engine? Is that what you're saying?
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Old 04-21-2017, 01:51 PM   #6
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Originally Posted by Robin97396 View Post
Apparently the charge still needs a charge controller to eliminate burning up either the alternator or over charging the house batteries.
Does the bus come with an OEM charge controller? If not, how does it prevent from overcharging the starting sytem batteries?
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Old 04-21-2017, 02:22 PM   #7
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So running the dual alternators would be the fix right? One for the engine and 12v accessories, one for the battery bank.
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Old 04-21-2017, 02:24 PM   #8
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Correct me if I'm wrong, but I believe Cowlitz is talking about idling to charge the house batteries. Even at a fast idle I'd only do that in an emergency.

My thoughts were being able to charge the house batteries while on the highway driving. For instance if I've been boondocking for a few days somewhere and then moving on to get a number of miles down the road I'd like to be able to use the alternator to charge the house batteries while underway.

I am electrically challenged, but prior conversations indicate that the alternator could get overdrawn from a large pack of house batteries and become burnt out. On the opposite end the batteries could get charged to fast, say from a HO alternator, and get wasted. It's my understanding that the charge controller levels out the power output of the alternator and charges the batteries without overheating or overcharging them.

I don't want to get a bunch of electronics. I went out of my way to get a mechanical bus so I don't want to fill it with electronics. I'd also like to be able to charge house batteries from a generator when necessary, but there still has to be some kind of charge controller from my understanding. I don't even know if that's what it's called.

The charge controllers are expensive, not unlike the batteries. I don't want solar. I just want to have a couple extra batteries to run 12 volt appliances, like a TV and water pump. I'm a minimalist. Trying to keep it simple.
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Old 04-21-2017, 04:28 PM   #9
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Quote:
Originally Posted by tlbeck1985 View Post
Hello everyone! We are purchasing our first bus tomorrow (hopefully!) and I'm trying to get a jump on the wiring diagram for our home bank, and well just about everything else lol. Being an electrician (apprentice) I'm anxious to start drawing this all out. I'm not having any luck with google or other forums. I was hoping one of you might be able to point me towards a service manual and/or wiring diagrams. Thanks in advance!

Also, after reading through a lot of these posts I had a question. Why are a lot of you running solar power or a generator instead of bringing the existing circuit from the engine bay to a disconnect, and then to your battery bank. If you're gonna burn fuel in a generator, you might as well use the one that came in the bus. This could also be a lifesaver if you were to lose a battery in the starting system. Close that disconnect and use your home bank to start the bus in an emergency situation. Just thought I'd share and see what you more experienced electricians thought about that.
First of all welcome to the forum. Not sure how much you have read here electrically. What year of apprenticeship are you in? How much DC theory have you studied? Have you any direct dc experience on vehicles?
I take it you are getting to know your bus electrical system.
For most of us, our buses don't come with onboard generators, did yours?

" If you're gonna burn fuel in a generator, you might as well use the one that came in the bus." Wrong choice of words there? Did you mean the bus alternator? So running the engine to have ample dc power for your needs? Wrong move there as another poster has already stated.
Alternators are not designed for that at all, only to top up the bus electrical system and starting batteries. Not many come with a "house battery" system. We add these. So that is what the alternator is built for, not extended recharging caused by house battery useage. That's where isolators come in handy and can be added. Read the current thread on isolators.

Your way wastes fuel, adds hours to everything electrically and mechanically and not at all cost efficient in any way.
Like I said, not knowing your background sure makes me wonder about your questions or theory.

When others talk about charge controlling etc, I am not sure of their knowledge either. A good battery charger is all you need that doesn't overcharge thus you don't have to babysit it. But it's not a bad idea to keep your eyes on it anyway as one never knows when things go wrong.
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Old 04-21-2017, 06:09 PM   #10
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Electrical dunce that I am, I questioned a friend who is an EMT about the systems on board their vehicles. Turns out, he can re-start your heart but isn't much ahead of me regarding things electrical. But, he did say their units run either a 250 amp alt or two slightly smaller that charge the starting battery, plus a bank of house batteries they use to run a lot of equipment off of. He knew there was some kind of "automatic controller" that directed the flow from the alt(s) to whichever bank needed power to stay above a certain level. He noted that their rig (basically an oversized ambulance) did have a separate A/C unit that was run off of either the alt directly with the engine running, or the battery bank with the engine off as well as a standard dash type A/C. As noted, he acknowledged a lack of understanding how it all worked, but said it was highly reliable.

Is anyone here familiar with any such systems? EMT units, Fire Trucks, etc.???
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