Bounder: Chassis batteries not charging?

[Taylorjbrown]

So, few months ago y'all helped me diagnose my house batteries not charging during trips, was a bad isolator.

I'm hoping someone can shed some light on this issue before my trip in two days.

So, my chassis batteries aren't charging when plugged into shore power. My house batteries around holding at ~13.2 on shore power. I noticed the other day that my inverter/charger was in overload/temp fault. Unsure why, I turned everything off for the night.

Before leaving for work I turned the shore power back on, house batteries were about 12.9-13.0. No fault/issues, chassis batteries at 12.1. when I switch shore power on, both battery banks jumped to ~13.9-14.2. ALL IS GOOD, whew!

Come back out a 9 hours later after work and back in fault, chassis batteries still at 12.1 and house at 13.2.

stumped, I did some research and asking on Facebook.

My searches on Google tell me that the system is designed, on shore power, to favor the house batteries on charging. When they get to roughly 13.2 it will automatically switch and charge the chassis batteries. It will then cycle back to house when they get low enough, them back to chassis when the house is roughly 13.2 again, repeating as necessary. I have learned that when my system says hey these batteries are good, switch and charge the chassis batteries now, that's when my inverter/charger goes into fault.

My isolator is 13.2 on house side and 12.1 on chassis side, could it be my isolator again?! Or deeper than that this time?

I've come to the conclusion that my system is not liking something within the chassis battery side, reason being: I closely monitored it this time, turned shore power on and house at ~14, checked inverter and green. The moment my voltage dropped to 13.2 on house and switched to charge the chassis, the inverter went into fault.

My inverter is a combi 458.
02 bounder 39R.
Shore power is 50amp.
I have a small 50w solar panel on roof to maintain while in storage.

*Edit*
When I press the aux start switch, chassis batteries and house batteries become equal at ~13.1

Now I'm wondering if it's my batteries themselves.

[okcnewbie]

I would certainly check the chassis battery.
You also need to check the LED's on the combi when it fails. The lights will tell you the type of failure hopefully.

[twinboat]

The isolator does not switch back and forth between batteries.

The inverter/charger always charges the house batteries. The chassis batteries are added under controlled conditions.

If your chassis batteries are failing, that may be overloading the inverter/charger, when they are added to the house batteries, causing it to overheat and fault.

You also want to confirm that the inverter/charger has air flow around it and the cooling fan is working. The fan only runs when its hot so testing may be tricky.

With the chassis batteries quickly dropping to 12.1 volts, ( 12.7 is resting volts ) I would suspect them and have them tested. That may be your whole issue.

[gatorv]

Go get a hydrometer at local auto parts or pep boys and check each cell. 12 and 6 volt battery's should have 2 volts per cell. Check when not charging battery. If one cell is dead and the rest have 2 volts each then you've found the failing battery and replace it. Be very careful as you are working with acid. Have clean water avail just in case.

[Taylorjbrown]

All:

Problem fixed.

Was able to load test them yesterday after work. Failed. I got new batteries and all is happy now.

House batteries are at ~13.5 and chassis is 12.7 and holding solid.