Chassis batteries not charging

[Steve Sauer]

Hi folks,
We have a 96 Monaco dynasty with the Xantrex 2012M inverter charger.

I went to start the motorhome up last month after sitting (plugged in with 50amp service) I did and got the following:
1) a click.
2) I then hit the switch that should make house and chassis batteries connect and got the same click (emergency battery start switch)
3) I tried to start the generator and got nothing
4) I checked the voltage on the chassis batteries plugged and unplugged from shore power (50 amp service) and there was no change (inverter/charger not working??)
5) I used jumper cables to jump the house and chassis batteries and was then able to start the generator
6) I immediately tried to start the cummins and that killed the generator
7) I restarted the generator and waited 20 minutes and the cummins started right up
8) I cleaned and/or replaced all battery terminal connections with no change

So, I have Xantrex model RV 2012M (manufactured in July 2003). My question is regarding path forward.

I turned the Xantrex off and waited and got no appreciable change in battery voltage.

I'm wondering if I have at least 2 problems (charger and emergency battery start switch).

Thanks to all who take the time to read this and offer assistance!

[OLYLEN]

Emergency start Solenoid, see post by Chiefdave same problem?

LEN

[Jimmyzw22]

When on shore power the chassis battery does not charge so it will go dead. I installed a Trik -L-Start that steals some of the charge to the house batteries and keeps the chassis battery charged. It is easy to install and works great. Make sure whenever you store it you disconnect the chassis battery.

[Robi.1014]

Steve,
I'll have to make some assumptions here, but here goes "by the numbers".....

"I went to start the motorhome up last month after sitting (plugged in with 50amp service) I did and got the following:
1) a click."
> Assumption: dead chassis battery-bank.

"2) I then hit the switch that should make house and chassis batteries connect and got the same click (emergency battery start switch)"
> Assumption: The "battery isolator" solenoid (that ties the "chassis" and "house" battery-banks together) needs 12VDC to work. Let's assume that this solenoid's electromagnet winding gets is juice from the chassis battery-bank. BUT: the chassis battery is so dead that this solenoid doesn't function. Hence all you get is a click.

"3) I tried to start the generator and got nothing"
>Assumption: the GenSet also starts from the chassis battery...which is dead. FYI, my GenSet starts from the house batteries, but to explain your problem as you describe tells me yours is wired differently.

"4) I checked the voltage on the chassis batteries plugged and unplugged from shore power (50 amp service) and there was no change (inverter/charger not working??)"
>Jimmy above is right: the Inverter/Charger charges only the house batteries. There is no "charge path" so that the Inverter/Charger can charge the chassis batts. Assumption: You didn't tell us what you measured, but my reasoning is that you measured something close to 12VDC, but the chassis battery-bank was in such a state of discharge that as soon as you put a load on them, their voltage falls to under 6 volts.

"5) I used jumper cables to jump the house and chassis batteries and was then able to start the generator"
>Assumption: Your house batteries were/are charged OK, and your jumpering them to the chassis battery allowed you to start the GenSet. See my assumption to your #3 above.

"6) I immediately tried to start the cummins and that killed the generator"
>Assumption: the GenSet electronics (the ECU) needs 12VDC to continue to do its thing. By attempting to start the main engine, you brought the poorly-charged chassis battery back down to 6 (or less) volts, and thus the GenSet ECU didn't have enough voltage to continue "doing its thing". Again: see my assumption to your #3.

"7) I restarted the generator and waited 20 minutes and the cummins started right up"
>Assumption: you left the jumper cables in place during this 20 minutes, right? (Please say yes.) Here's what happened: For 20-minutes, the GenSet provided AC power to the Inverter/Charger...and thus the chassis batts got a charge because you had the jumper cables in place.

"8) I cleaned and/or replaced all battery terminal connections with no change"
>Assumption: do you mean that you're back to square one?....that of getting a "click" again? How long did you run the main engine?...which is also to ask: how long did the alternator (on the main engine) charge the chassis batteries? If the chassis battery-bank was dead-on-its-ass (as I have assumed), then they will need much more than 20 minutes of charging to get them re-charged. BTW, a starting battery with a dead cell will seem to take a charge (and might start an engine immediately after the charge is completed), but within a several minutes or an hour, it won't start that engine. Nada.

[HeapBigEngin]

Robi.1014....I read the original post with interest, hoping I could learn from this situation. Your step by step analysis is outstanding and one of the best I have read in a long time. Excellent! Sounds like dead or "gone" chassis batteries to me. Steve....hope you track down the problem, and please keep us informed of the outcome. Thanks!