Battery Charging

[burton822]

Does the generator charge the battery under the hood. We had to jump the The battery under the hood in our motor home to get it started. If we run the generator will it fully charge this battery. Thanks for any help on this matter.

[8.3Oilbuner]

Good afternoon Burton822; Charging of the chassis battery depends on how the coach manufacture configured the battery charging system either through the on board converter or inverter. Do you know which system you have? I am versed in Monaco products as owing them for the past 13+ years. Some models depending on level in the line up, lower cost to higher cost, have battery charging systems that thru the inverter charge both the house and chassis batteries when hooked to shore power or when running the generator. Some models only charge the house batteries and not the chassis batteries or battery. One sure fire way you could check this is with a multi- meter. Before you start the generator, check the voltage at the house and chassis battery. Now start the generator and re check the voltages. I am going to guess that you will only see a voltage increase on the house batteries and not the chassis battery. This means that the coach manufacture has designed the charging system for the house batteries only and has left charging the chassis battery up to the alternator only. You can buy a small charger to hook up to the chassis battery when camped to keep it charged. Hope this gives you an answer. Hope someone with your year and make of coach will respond here to give you a more precise answer. Good luck!

[ronsteward]

For the benefit of others, I am going to tell the whole story. First off, my Allison Transmission brain was fried which cost me about $5K total. After I got that fixed, my chassis battery went bad. I tore my MH apart trying to find where mice had chewed into the wires. There was a short somewhere. I found evidence of mice but no evidence of where they chewed thru. I replaced the battery maintainer but no help. The battery would go dead with shore power connected but over charged when motor was running. How does a battery discharge when a maintainer is hooked up to it? Nothing made sense. I bought a new battery which helped but was still being over charged with motor running so it had to be the alternator but I was discharging battery with shore power hooked up but not as bad. As of right now the alternator is in the shop, the wires are marked and secure, the old battery maintainer is hooked up and shore power is connected. Everything is working like it is suppose to except I don't have an alternator. Evidently there was a short in my alternator which was overcharging my battery when running and draining my battery when not. This sounds crazy but it is what is happening. If someone has a problem with shorting out but you do not have evidence of mice chewing wire or even any mice at all, you may have the same problem I have had. If you start to see tour alternator over charging you should park your rig immediately and hopefully save your transmission brain. BTW If your Allison transmission cannot get a signal that it is in neutral, your motor will not start. Allison Transmission brains (the computer) cost about $3500 plus labor and they charge $165 an hour labor at an Allison Transmission authorized dealer. I hope this helps someone.

[YC1]

Ouch. I paid $1000 for my ECM in October. I diagnosed it myself and took it to the dealer. They programmed a new one and handed it to me in 30 minutes.

An alternator can indeed run a battery down. I have seen it happen. Only once in 40 years so it is rare.

If your shoreline charging system is wimpy it cannot keep up with a serious drain.

I mean wimpy as in a Trik-L-Start, or some small maintainer. They are just that and do not supply the full charging current of the onboard charger.

The symptoms were so goofy on my ECM that the engine would not start. The symptoms changed once I found the water entrusion and hoped that cleaning up the contacts would work. But alas, water was inside and made the thing go absolutely bonkers.

Bonkers is an electronic term used by highly skilled certified electronic techs. It is not to be used by amateurs. It can cause confusion such as the term "short".

Sorting these things out is not for the faint of heart or ones without a big budget for the hobby.

You have to be handy with tools, a checkbook, and a voltmeter.

[aether_one]

Originally Posted by YC1

Bonkers is an electronic term used by highly skilled certified electronic techs. It is not to be used by amateurs. It can cause confusion such as the term "short".

Ain't that the truth!

[burton822]

I love this site. thanks everyone for your advise unfortunately we are not mechanical incline after running generator for a while yesterday, we tried to start MH this morning and did not start. we are just going to get a new one. Hope this solves the problem.

[ronsteward]

Ok, I had the alternator rebuilt at Alternators of Knoxville. Very nice people. Highly recommended. Cost me $137.73 with tax. Now another problem. When hooked to shore power the 'alt charge' light comes on in the dash and the alt gauge jumps to about 14.5-15 volts for a few seconds then goes off and gauge goes down for a few seconds and then back on. If I unplug shore power, everything acts normal. I don't remember this happening before. Any ideas what could be wrong. Should I not run engine when plugged into shore power. (I have 50 amp service at my home)

[twinboat]

I'd unhook the chassis battery maintainer, as a test, to see if it stops.

Something seems wrong with the alt wiring.

[YC1]

Not an unusual problem. There is just a bit of a conflict with two charging systems going on at the same time.

If you were running your generator the issue probably would not come up because many devices isolate the two charging systems if the generator is running.

Turn on your headlights on bright and the problem will probably disappear.