Troubleshoot after dead battery

**1adam12** · 08-30-2021, 11:22 AM

I had to replace the battery on a 2019 Momentum 397. Everything came back on seemingly ok. I turned on the generator and then the interior coach lights and one AC (center) unit. After several minutes all the lights and AC shut off. The generator was still running. Any ideas where to start looking for the issue?

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**Hoopy Frood** · 08-30-2021, 11:24 AM

I'd start with the generator circuit breakers.

**1adam12** · 08-30-2021, 11:25 AM

Will do - thank you

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**huntr70** · 08-30-2021, 01:37 PM

Lights are 12 volt, so maybe converter?

**Hoopy Frood** · 08-30-2021, 01:56 PM

Converter shouldn't have shut down the AC though. Although the converter could also be bad. WFCO are not renowned for their quality.

**1adam12** · 08-30-2021, 03:29 PM

Originally Posted by huntr70

Lights are 12 volt, so maybe converter?

I’ll add that to list of items to check - I know it’s behind the false wall

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**Jerryr** · 08-30-2021, 03:37 PM

Originally Posted by Hoopy Frood

Converter shouldn't have shut down the AC though. Although the converter could also be bad. WFCO are not renowned for their quality.

Are your sure that 12vdc isn't required to operate the thermostat? Looking at the Dometic wire diagram there is a 12 vdc input

**1adam12** · 08-30-2021, 03:44 PM

Just FYI I chatted with Tech Support today from the dealership - they also suggested checking the cables for the battery to make sure they were put back exactly correct - I banded them together when I removed the battery so I’m pretty sure they are - I know the positive and negative are correct but there were at least two other cables on each side that I’m hoping I didn’t cross by accident- if anyone has access to their coach I would really appreciate a few pictures of what cable is going where on both negative and positive side of battery - thanks

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**Hoopy Frood** · 08-30-2021, 04:07 PM

Originally Posted by Jerryr

Are your sure that 12vdc isn't required to operate the thermostat? Looking at the Dometic wire diagram there is a 12 vdc input

Good point. I hadn't considered that.

**hartcentr** · 08-30-2021, 05:24 PM

Originally Posted by Hoopy Frood

Good point. I hadn't considered that.

12 volt is required to run the thermostat. With AC plugged in, simply switch the batteries to off and while looking at a still working thermostat, flip the breaker to off on the converter. The thermostat will go dark.