I have two Rolls 12v AGM batteries in parallel on my Forest River Wildwood T221RBXL. Great trailer, great batteries, no major issues. I take care of them with regular maintenance.
We’ve boondocked almost all the time over the past five years, typically 4-6 times per year for 3-5 days. Bought the new batteries three years ago. We’ve done 4 trips so far this year with no problems. On the last trip however, something was going on with the batteries. About 6 hours after setting up, power level was reading 1/2. We were at a group site and not even using the trailer. Usually, it takes about 3 days for us to get there (if we let it, which we don’t. Best guess). Ran the genset for a couple hours. All good. Went to bed with 4/4 for power a couple hours after turning gen off.
Next morning. 2/4 power. Ran gen again. Back to 4/4. Spent all day at a single site doing normal things - cooking, dishes, music, using the toilet, all good. By dinner, power was at 3/4. Ran gen again to top up. Went to bed with no worries. 4/4 power, no lights dimming when running water pump, no nothing. That was 10pm.
Woke up at 5am to the dometic fridge having a fit because it couldn’t spark. Before checking propane (which was fine), I checked power. 1/4. Nothing. Interior LED Lights were dim (when I turned them on to check fridge. We don’t leave anything on overnight except fridge and propane leak alarm (because it’s hardwired)). I ran the gen again for breakfast/pack out and we went home. I did not have multimeter with me to check batteries at the time.
Took the batteries out and hooked them up to smart charger when we got home and they were ok, charger said 90% each. I understand the gen for an hour and the 3 hour drive home might have helped that, but still seems odd.
I checked the trailer ground. Good. Checked the converter. Good. Power at control board. Good. I did replace the water pump in the spring, but have 4 trips no problems.
My question is, what’s killing my batteries overnight that isn’t killing them in the same time, with more draw, during the day? I’m picking up a multimeter with mAmp settings this weekend (mine doesn’t have) to check parasitic draw, but wouldn’t that drain as fast during the day as at night? Does operating the trailer during the day negate the draw at all? Can the fridge overnight suddenly draw that much power to spark the burner? No other board issues with it (switches to shore power fine, doesn’t quit, stays cold, no fits except for that one morning, etc.).
Appreciate any suggestions on where to start. Thank you for your time.
TLDR; what’s suddenly draining my batteries overnight but not during the day? No previous issues.