Battery Light on Monitor

[LadyRVer]

I have a 2018 Keystone Hideout travel trailer. On the gauge monitor, the tank monitors are working. The battery doesn't show any lights. All 12 volt items are working fine, awning, thermostat for a/c, water heater starting OK, etc. Any suggestions what to look for before I call a mobile RV tech ($$$)? Batteries (2) have water, just checked the other day.

[pianotuna]

Bobbo wrote:
What is "voltage at rest under load"? I thought "at rest" meant "no load."

Thanks for catching that.

I meant rest the battery for 24 hours, then test voltage. Now put a load on (30 amps or so) and test voltage again.

Sorry to be "unclear".

[Bobbo]

What is "voltage at rest under load"? I thought "at rest" meant "no load."

[pianotuna]

LadyRVer wrote:
I checked the 12 volt plug in the trailer with a 12 volt meter. It read 13.3. I am plugged into shore power. I am thinking I also need to shut the 30 amp breaker off and then check it again? I don't have a multimeter.. yet.

A volt meter will tell you what you need to know.

I'd measure

voltage unloaded

voltage loaded (fridge on 12 dc or all the lights on)

voltage at rest (24 hours of no load and no charging)

voltage at rest under load.

[LadyRVer]

I checked the 12 volt plug in the trailer with a 12 volt meter. It read 13.3. I am plugged into shore power. I am thinking I also need to shut the 30 amp breaker off and then check it again? I don't have a multimeter.. yet.

[Boomerweps]

At first blush, the installed battery monitor might be faulty. Use a multimeter to test the battery with and without the battery disconnected. You can get an online chart of various state of charge voltages for the battery type. Battery should be tested “at rest”, after being disconnected from any charger for a while. Check its voltage with the charging operating, should be over 13.6 VDC.
I bought a budget shunt that came without connecting cable ;( Awaiting the cable from Amazon. My first LiFoPO4 battery has Bluetooth monitoring so I can check and by proxy, the second battery that is in parallel with the first.

[LadyRVer]

Thanks for the suggestions, Pianotuna. Will do before I call mobile RV tech.

[pianotuna]

Hi,

As the battery lights are a crude and inaccurate method of capacity, I'd upgrade to a volt meter (one of the type that fits a cigarette lighter).

If that is not "good enough" then move to a meter that has a shunt which is about the best that can be found. Victron makes an excellent unit.