Puzzling power Problem

[happycampersigns.com]

My 2019 Precept 31UL came from the factory with two sealed 6 volt AGM batteries. Last week I was boondocking, ran the 1000 watt inverter all night for refer and cpap, 8 hours later... I was surprised to see that the POS gauge still read full. Very happy with performance and without having to check battery water! BTW, they are Harris Batteries.

[NickM]

I picked up my 35S yesterday after 60 days at the dealer for service and of course my pair of Energizer deep cycle AGM batteries were dead. Dealer says nothing in the coach is draining the batteries but yet they do not hold a charge, and they are only 5 months old.

Dealer measured .26 amps current draw with the master switch off. There is a problem in the coach somewhere and now that it’s out of warranty I will conduct my own research to find the culprit. I’ll also be installing a battery disconnect switch before our next trip.

Wish I had that kind of battery life happycamper.

[pokergeist]

Originally Posted by xraymiller

I have a multimeter, but I don't think it is a TrueRMS (which I never heard of). Do you have a system or method of testing? For instance, turn master switch off check voltage (and/or amps). Turn main power on, check. Turn on inverter, check. Something like that?

XRay - you don't need an RMS (root mean squared) meter for measuring DC voltage in this scenario. The RMS feature is for precisely measuring the average voltage or current of non-sinusoidal AC signals. Your battery voltage is steady-state DC for the most part.

A meter that captures min/max values might provide some insight when heavy loads or charging systems switch on and off, but that's probably a minor curiosity.

[pokergeist]

Originally Posted by xraymiller

...

But I do have a new question relating to the inverter. The RV manual has 3 paragraphs on it. I’m a little confused on when to actually turn it on. I assume if I’m hooked up to shore power or on the generator that it doesn’t need to be on. But then if it’s only used when boondocking, it will run the batteries down quickly (because of the fridge).

Regarding your other questions: You should have a manual for your inverter. We have a stock Xantrex inverter that passes AC power through when on shore or generator power. Inverters are inefficient, even with no load, so we leave ours off except when we need it. (Ours has a low power "load sense then on" mode which I typically don't use.) Our inverter displays coach and chassis (Freightliner starter) battery voltage.

The battery disconnect switch is a great idea. The CO (and smoke?) detector is on even with the coach power switch off. Lead acid batteries self discharge, and like to be stored at full charge. So a full absorption charge, float charge, and occasional equalization charge are recommended - all of which is taken care of by our stock Progressive Dynamics charge controller if on shore power. Otherwise, monthly battery charges while in storage may be beneficial. Charging info and everything else at https://batteryuniversity.com/learn/article/charging_the_lead_acid_battery