What am I missing? 12V trailer power, or lack thereof....

So, after letting the battery sit for a bit on my trailer without a tender, it was flat as a pancake. Unfortunately, this meant neither the winch or power tongue jack was going to work too well, and I could really use both to move the Camaro to the fab shop this week. I put my old Schumacher charger on it and let it charge up for a day or two...even tested the up/down on the power tongue jack once yesterday and it worked as expected. I pulled the charger, button everything up today, and check the winch and jack...no luck. Checked the circuit breaker for the tongue jack, not tripped. I thought I might have heard a click or two from the winch solenoids at first, but no longer.

Checked the battery with two multimeters (first one had readings all over - 10V to 17V), and I'm getting north of 12V on the second one, so the battery does seem to have a charge. Any ideas? My next step is to pull the battery out of the trailer (a bit of a PITA I'm not looking forward to based on location under the deck) and see if I can get it tested...it's not exactly farm fresh. Possible there's an internal fault? Hoping I didn't somehow nuke the winch and tongue jack motor, as I may not have been smart enough to disconnect them during charging.

I think the likelihood of a bad battery cell or grounding issue is more probable than 2 unique and different hardware failures. I'd start with the batteries and go from there.

I can't imagine that having the winch and jack connected during charging would be problematic. I mean, the car is charging the battery when you're driving and the jack and winch are connected then, right? I know they would be on a regular toy hauler or travel travel.

I would place my bet on bad battery. I've had batteries test good, yet when the "good" battery is the only thing replaced in the whole system, suddenly everything starts working just fine.

Put you working voltmeter across the battery. Check the voltage. Try to use the winch. What's the voltage across the battery when the winch is trying to run?

My bet is bad battery.

Monitor the voltage under load or put it on a load tester, even deep cycles don't like sitting around dead. If this is a conventional wet cell battery you can try popping the caps off and putting it on one of the big dumb chargers (the roll around start a car style) at max rate for a while, let it "boil" (Danger: Hydrogen, no smoking!), that sometimes will make a dead battery a useable battery for reasons I don't fully understand (cell balancing?).

One amp can be had at 12v. But one app isn't moving either of those devices. My money is on new battery

I had a battery do that in my old Ford Explorer.

Would charge no problem, would read decent voltage but as soon as you put a load on it, bam - no good.

You have one completely dead cell.

Thanks guys! I'll crawl under there and pull the battery out this morning and have it tested, as it sounds like this one is pooched. It will give me a good excuse to hook up the Battery Tender SAE leads to keep the new battery healthy so it's charged and ready to roll when needed.

Hopefully we'll be powered back up this afternoon!

Many thanks guys - the battery was shot. Apparently after 5 years of abuse, it finally decided to give up the ghost. Popped a new one in and all 12V accessories are working as expected!