Battery Drains Fast

grkunkel · January 2

I have a 10 mo old Interstate group 24 Deep Cycle battery. It was fully charged after our summer of full hookup camping trips and then sitting parked for severaL weeks in our yard connected to shore power. Then I unplugged our 2016 320S from shore power for almost a month. Today I checked battery voltage on the SeaLevel panel and there was no reading. In fact I had no interior lights, no radio, no CO detector, no smoke detector ..... no nuttin'. I plugged the trailer back into shore power and everything was fine once again. The battery immediately began registering a voltage at 13.6 volts, and then settled back down to 13.5. I never touched the battery cutoff switch since installing the new battery this past spring; I left it on throughout the year. I can't imagine why the battery would drain entirely during that month of disconnection from shore power. The only devices left running while disconnected from shore power were the things that don't turn off ... the detectors, the blue clock display on the face of the radio, and an indicator red LED or two around the cabin. The Norcold refrigerator was not running. Any ideas about what might be happening here? Certainly the battery should not fully drain when unhooked from shore power for a month. Should it?

jmcgonig · January 2

You probably only have 50amps total. So a little over an amp a day would drain your battery. That's not alot. So you probably killed it. You also probably damaged the battery by draining it too far so now it won't last even that long. If you aren't connected, you should disconnect the battery using the switch.

VictoriaP · January 2

Actually, yes, the parasitic draw from those things will drain your battery in under two weeks…exact time varies by battery bank size, and a group 24 battery has very little usable capacity overall. That’s why it’s recommended you use the cutoff switch during storage unless you’re plugged in.

This is also why a lot of us have installed inline kill switches on every device of that type that we can. The radio & TV are two big culprits (and not just when the LED clock screen of the radio is on, but when it’s theoretically powered off), but there are some, like the fan & propane sensor, that you don’t necessarily realize are pulling power constantly from the battery if the battery disconnect is left in the on position.

Grumpy_G · January 2

My trailer pulls ~0.3A just sitting, the drain is from the CO/propane alarm, TV & radio in standby and the little blue LED in the bathroom light. Multiply by 24 hrs and the battery loses 7-8Ah worth of charge in a single day. The Interstate group 24 is about 60 Ah (although they rate them a little more optimistically), so the battery would be fully discharged in about 8 days.

For reference, a modern car stuffed full of computers is around 20mA (0.02A) at sleep so it can sit much longer.

pthomas745 · January 2

My 2017 parasitic draw is about 4 amps a day. Your 80 amp hour battery used up 50 percent of the available amp hours in the first 10 days of being left with the battery switch on. Once a battery gets below about 12.0 volts, the battery will have less capability of holding any charge as the draw continues.

The SeeLevel is not a good battery monitor. When you plugged in your trailer, the "13.6V" it showed you was nothing more than what the WFCO charging was sending to the battery to charge it. A reading of a lead acid battery being charged, or being discharged by anything, is not the actual state of charge of the battery. It would take many hours of charging to return those 80 amp hours of the battery.

The battery switch should be off whenever the trailer is stored and not plugged into shore power or has a solar panel connected.

You should have the battery checked to make sure it has not been damaged by this trip to the "dark side" of a very low charge. Hard to say how long the battery sat at a "zero" or close to zero state.

The other thing you need is a battery monitor that will work with the battery switch off. Something completely independent of the trailer. A multimeter is a common tool for this "battery monitoring" need. The SeeLevel monitor, and all the monitors built into the trailer, are always lying! If the battery switch is on, they will read too low.If the trailer is being charged, it will read too high.

You can find an inexpensive meter at Harbor Freight, etc. Not hard to use, we can show you how to use it and what to do with the information you get from it. This is a basic Amazon selection.

https://www.amazon.com/autoranging-multimeter/s?k=autoranging+multimeter

PS: don't feel bad! Many of us had to learn some hard lessons about the bewildering world of batteries!

Sharon_is_SAM · January 2

@grkunkel - Lesson learned regarding the battery switch and parasitic drain. if you need to replace your battery, an AGM is more forgiving and essentially maintenance free. It discharges very slowly. Best practice is to fully charge your battery before storage (we use a smart charger), then turn off the battery switch. We leave our TaB stored for 6-7 months and it still reads 100% when we pick it up from storage. It sounds like you use full hook ups while camping, but you still need a viable battery while towing. As Pthomas745 noted, it is good to know the health of your battery by checking the voltage while the battery switch is off and the battery is isolated from any power draw.

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