Chassis versus House Batteries

[deadeye916]

2018 Windsport 35M and for the life of me I can't figure out:

1. Why the chassis battery goes dead while drycamping

2. Why the auto-gen start appears to be engaging when the chassis battery is below 11VDC (see #1)

My specific rig does not have a BIRD relay.

If I leave the rig in storage with the salesman switch turned off, when I return a few days later all my batteries will be dead. I have to jump the chassis battery, then use the EMERGENCY switch to get the generator started.

I am fairly confident the chassis battery is shot...driving back from AZ recently the inverter was throwing an error out and shutting down and reporting 10.x volts from what ever source it was monitoring. I assumed it was the chassis battery. When driving I would have thought the alternator would provide enough juice to both sets of batteries to keep the inverter working for our residential fridge.

I've been thinking the chassis battery is shot because I've had to jump start the rig 2 times. I put a knife switch on the chassis battery so I can disconnect it while in storage but wondering if I need to add one to the house batteries as well. Any thoughts?

[Oneilkeys]

I can’t believe your Windsport does not have a BIRD, BIM or BCC. I think all Thor Class A’s have a means to charge all the batteries whether in engine, generator or shore power. Easy to check. Buy a cheap volt meter, turn in the generator or plug in and see if the voltage on the chassis battery changes to around 13.5v or more when you do. Sounds like your chassis battery is shot. The chassis battery is not a deep cycle and it cannot take very many deep discharges before it is toast. NAPA or any auto store will check it for you.
As to the coach batteries, have them checked at the same time. The way these coaches are designed, they will slowly discharge if the coach batteries are not knife switched too.

[Nursx2]

Thor places junk batteries in the motorhomes to sell them.

[Oneilkeys]

And the WFCO converter/chargers are not any better. Often, just replacing the batteries and not the charger will just lead to more dead batteries. You need to check both.

[Judge]

One of the best upgrades I did was replacing the WFCO Converter / Charger with a Progressive Dynamics model with an Equalization Mode.

As mentioned a Converter / Charger upgrade can save you money in the long run in better battery life.

[Oneilkeys]

Yes, the PD 4655 is a direct replacement for the WFCI 8955 in my Axis. I replaced mine three years ago and have been very pleased with it.