Battery down under 5v- what happened?

[Eazy]

Trying to solve a mystery I just discovered with my electrical system.

Some background:

- brand new 12v 'true' AGM deep cycle battery (UB121000)
- recently replaced power converter, including DC board (PD4655)
- converter appeared to be working flawlessly
- DC system appeared to be working flawlessly, we dry camped with the new battery/converter for 3 nights and finished with about 1/2 charge on the RV gauge which seemed good for how much power we used.


After that weekend, we stored it, and I also plugged in a 12v solar panel trickle charger (sunforce 50022 5 watt) that I used on my old trailer without any issues. On this new-to-us trailer, the only 12v socket is the TV antenna jack, so I (perhaps foolishly) plugged it into that thinking it would work as my old system did, and pushed the button on the jack, thinking that would 'open' the circuit between battery and solar. Typing it out it sounds awfully suspicious and naive, but you tell me.

Next time we came out to the trailer, the battery is functionally completely dead. Seemingly no power at all except to light up the LED indicator lights on the DC board.

Today I took my multimeter to it and was very surprised to see it reading only 4.8v! I unhooked it to take it home to try and diagnose, and noticed a divot with some green stains on the outer case of the battery, directly under the neutral line, as if it had been very hot and melted a small divot.

Now unhooked to anything, it seems to actually be gaining power...? It's up to 5.1v in about 2 hours of sitting idle.

The solar panel is a few years old and has some wear and tear, including a few areas where the outer wire cable has stripped and kinked (but not to expose bare wire, only the dual wires contained within the outer casing). It's putting off about 9v when exposed and just a few millivolts when covered.

What could be the issues? Things I've considered:

- a short in the DC system. I sure hope not, this will be harder to resolve.
- a bad battery/cell. But it's brand new and worked great for a short while.
- the antenna jack won't work for this and somehow the solar panel is to blame?
- DW left the fridge door open to try and keep air moving in the fridge. We didn't see any lights but maybe there's something else drawing?
- mystery draw in the trailer just happened to drain the battery completely. But would a normal draw like a LP detector draw it down below 5v?

I haven't yet charged the battery, nor taken it to get checked at an auto parts store. Also I didn't think to manually check the DC fuses in the panel, however none were lit up, even though the DC board green light was on.

Any ideas what I might be facing here? Is my new battery screwed already? Thoughts on next steps?

[raspivey]

Originally Posted by Eazy

- DC system appeared to be working flawlessly, we dry camped with the new battery/converter for 3 nights and finished with about 1/2 charge on the RV gauge which seemed good for how much power we used.

1/2 Charge on the panel is most likely less than 1/2 charge on the battery...they're not all that accurate.

After that weekend, we stored it, and I also plugged in a 12v solar panel trickle charger (sunforce 50022 5 watt) that I used on my old trailer without any issues.

5 Watts is nowhere near enough to recharge. The most you can expect out of that is to maintain once charged.

Now unhooked to anything, it seems to actually be gaining power...? It's up to 5.1v in about 2 hours of sitting idle.

That's somewhat normal and indicates you had a draw on it prior to disconnecting it.

It's putting off about 9v when exposed and just a few millivolts when covered.

Again, nowhere near enough to recharge a depleted battery. You'll need 14V or more to completely recharge. Seriously consider spending $100 or so for a good smart charger if you're going to dry camp like that very much...it's cheaper than new batteries.

But would a normal draw like a LP detector draw it down below 5v?

Yes, that alone will hurt a battery in a week or so if fully charged, much less one that's half charged or less.

I haven't yet charged the battery, nor taken it to get checked at an auto parts store.

Along with not discharging below 50%, charging ASAP and keeping them that way will keep them happier longer.

Any ideas what I might be facing here? Is my new battery screwed already? Thoughts on next steps?

Maybe not toast, but the life has probably been cut pretty good. Next steps...get it charged, get a good charger, keep it charged, and disconnect it when not in use. Also, don't rely on those panel lights. While not extremely accurate, I just use a multi meter and check voltage once a day..generally after we've been away for a while with minimal draw on the batteries.

[Eazy]

Thanks for the reply. Sounds like you're thinking it just simply drained due to normal draw from LP detector and such. If so, I suppose that's better than having some kind of chronic short. I'll get to ordering a smart charger and a battery cutoff switch.

What about the small cable-shaped divot on the battery casing? Nothing to worry about?

[Too Tall]

I would see if I could bring it back and have it replaced. It sounds like an internal battery problem if you can see physical signs of overheating on the outside of the battery.

[boondocking]

If your solar panel is putting out 9v that is not going to maintain your battery. The normal draw from the CO/Propane detector etc would not be covered by that solar panel either. You need at least 13v with some amperage to maintain the battery.

[rsdata]

do a google search on AGM chargers... AGM batteries have special needs that a regular charger does not always provide...

you have harmed the battery, but it might come back for you to get some use, but never back to original spec's

How about taking a picture of the damage you see on the case???

[Flybob]

Those small solar trickle chargers are nothing more than a gimmick. The do not produce a high enough voltage or enough current to do anything. As mentioned above, it would not even operate the CO/Propane detector. Dry camping for 3-4 days on one battery is a challenge. Once you get the battery charged back up, I would take it to a battery dealer and have it load tested. The battery lights on the control panel are a best guess only.

[Too Tall]

Originally Posted by Eazy

Trying to solve a mystery I just discovered with my electrical system.
Today I took my multimeter to it and was very surprised to see it reading only 4.8v! I unhooked it to take it home to try and diagnose, and noticed a divot with some green stains on the outer case of the battery, directly under the neutral line, as if it had been very hot and melted a small divot.

IMO, if the battery got so hot as to melt the case, it would take an extreme amount of amp load which would have popped breakers and fuses. since everything is working, it seems an internal short would be more likely. Simply, killing the battery over time, would not melt the case.

[VinceU]

Get a real voltmeter and monitor the battery during charging and use. Get information on AGM batteries, max voltage drop and charging voltage which are different than lead acid batteries.


Sent from my iPad using Forest River Forums

[Too Tall]

The craftsmanship clip-on DC/AC amp meter (about $49) at Sears is one of the most useful tools For finding out what your current flow is.

[Iwannacamp]

FWIW Don't forget your brakes. IMHO whatever did this was a high amp load(if battery is ok) and then opened the circuit. If it didn't fail... it would have pulled the battery to 0.
You might be able to smell the "hot item"

[raspivey]

Originally Posted by Eazy

- DC system appeared to be working flawlessly, we dry camped with the new battery/converter for 3 nights

After that weekend, we stored it, and I also plugged in a 12v solar panel trickle charger (sunforce 50022 5 watt) that I used on my old trailer without any issues.


Today I took my multimeter to it and was very surprised to see it reading only 4.8v!

I don't believe it's a battery issue, shorted or otherwise. Although interesting, I think the "melted" part of the battery casing is a separate issue IF it's even an issue. After three nights of use, I'd expect the voltage on that battery to be down in the 10.5 - 11.5 V range to start with. CO detector could very well drop that to 5V in a few days with a .6A current (5W @9V) not keeping up. It didn't just run a battery down from 12.9V to 5V in a day....I'd be worried if that were the case, but it doesn't sound like it.

Breakaway engaged IS a possibility though.

[ScottBrownstein]

Hopefully you have now charged your battery on a real charger and the voltage has returned to 12.6 or so. If after sitting the voltage isn't above 12.4 or better, the battery is toast. I agree with others that after a few days you probably had discharged at least 50% of your capacity and that would be normal. That solar panel will not recharge a discharged battery. The panel can put out the more than 13 volts needed to put a little charge in the battery (when you have really good sunlight for 4 or 5 hours) but it will take a very, very long time to actually charge a battery...forever if there is even a very small parasitic load like a CO detector or something else. As far as the 9 volts of output is concerned, the panel will do absolutely nothing unless it puts out more voltage that the current battery voltage in order to put current back in the battery.

Now if your battery has charged to over 12 volts, that is not an indication that everything is OK. If you deeply discharge a lead acid battery (AGM is lead acid) and leave it for a while, it will permanently damage the battery or at the very least permanently reduce its capacity. Getting it checked will only prove that it can put out significant current not that it can do it for more than the few seconds it is on the tester. Testers are good at showing shorted cells, not battery AH capacity.

All you can do is charge it, try it and see how much capacity it now has. A 12 volt battery that measures 5 volts is completely discharged and that has probably hurt the battery.

Finally, did you verify that when you plug it in to the 12 volt TV outlet it actually will send voltage to the battery on this "new to you" unit?

[shooter2]

Your new trailer probably has more parasitic loads than your old trailer.
Your parasitic 12 volt loads would also include 12vdc TV sets, TV antenna amplifier,fridge and etc.

5 watt panel will not keep up with even CO detector, mid summer at the equator. 12volt panels are only 18% efficient at best, That means that only 18 watts are available from a 100watt panel with a high end MTTP controller, clear sky, sun directly overhead will put out about 5 amps @ 14vdc. That is equivalent to a low end cheap 15$ 110vac battery maintain charger from Gypo tool..

Just my experience

[boondocking]

Originally Posted by shooter2

12volt panels are only 18% efficient at best, That means that only 18 watts are available from a 100watt panel with a high end MTTP controller, clear sky, sun directly overhead will put out about 5 amps @ 14vdc. That is equivalent to a low end cheap 15$ 110vac battery maintain charger from Gypo tool..

Just my experience

I think you are a bit confused.
At 18% efficient means the panel will convert 18% of the sun energy into electricity. A 100 watt panel can supply a 100 watts to the MPPT controller with clear sky and sun directly overhead.
A panel putting out 5 amps @ 14vdc=90 watts. = 90 watts.

[shooter2]

You are correct I was confused,.