"Reviving" an AGM battery.

[outdoornate65]

I have an auxiliary 100 ah AGM battery that I use in my 4-Runner to power my Engel Fridge. A 100-watt Renogy solar panel is my only source of power to maintain the battery while it's in the rig.

Last fall I was on a week long river trip in Canyonlands and left the fridge running (cold beer when we return) while the truck was parked at Tex's. Unbeknownst to me, I had a loose wire from the solar panel where it connected to the solar controller and ended-up having a deeply discharged battery when we returned.

I took the battery out of the truck and brought it inside for the winter and didn't give it much though. A volt meter wired to the battery read 12.0 V when I finally got around to checking on it the other day.

I hooked-up my battery charger and the "reconditioning" light came on. The manual said the charger would slowly "recondition the battery" until it was ready to take a charge.
The charger remained in that state for two days and never changed.

So my 12-volt newbie question is: Have I ruined the battery or is there a way to bring it back to life? If so, how do I go about doing that?

Thanks,

Nate

 

[dreadlocks]

My money is on toast, you could try giving it a static 14v charge for a while to see if it comes back but if it does it'll never be like it used to be capacity wise.. just a shell of its former self.

no lead battery likes to be stored long term discharged, this is what did you the most damage.. Ive done it before with an AGM, they wont tolerate this at all and it sucks when it wont come back, I feel for yeh.. I'd suggest you replace with a Trojan FLA battery in and a hardwired battery maintainer, a LVD would be prudent too.. FLA takes more abuse than AGM and if you do abuse them to death they are easier to replace financially.. AGM's provide practically no benefit for running a fridge other than lightning your wallet.

 

[john61ct]

A standard 20-hour load test is the only way to know without very expensive lab gear.

That said if not mission critical give it a try, might last a few dozen more cycles, maybe a few hundred, maybe reduced capacity or might explode.

 

[outdoornate65]

My money is on toast, you could try giving it a static 14v charge for a while to see if it comes back but if it does it'll never be like it used to be capacity wise.. just a shell of its former self.

no lead battery likes to be stored long term discharged, this is what did you the most damage.. Ive done it before with an AGM, they wont tolerate this at all and it sucks when it wont come back, I feel for yeh.. I'd suggest you replace with a Trojan FLA battery in and a hardwired battery maintainer, a LVD would be prudent too.. FLA takes more abuse than AGM and if you do abuse them to death they are easier to replace financially.. AGM's provide practically no benefit for running a fridge other than lightning your wallet.

Thanks Dread. I see you're in Denver.....I'm in Centennial. Might have to buy you a couple beers and pick your brain about my 12-volt set-up sometime. As I said, I'm a total newb when it comes to 'lectricity.

 

[dreadlocks]

whats its resting voltage now after being reconditioning for a few days? Check that, then hook a 12v load up to it.. hook your fridge back up and see how long it runs.. My last 100AH AGM battery died when I brought it home after a trip deeply discharged, put it in the garage, plugged it in to charger/tender and neglected to notice power strip I plugged into had been turned off, I was beat from a long day on the road.. didnt realize for a few months because that was the last trip of the season, then no amount of time on the charger would run the fridge for more than half a day or so.. when it used to do two days pretty easily on its own.

Knowing how much runtime you got is critical with a fridge, if you keep perishables in em.. for me its beyond mission critical because I need to keep medications cool.

I work in Dove Valley, so I could take yeh up on a beer.

 

[outdoornate65]

whats its resting voltage now after being reconditioning for a few days? Check that, then hook a 12v load up to it.. hook your fridge back up and see how long it runs.. My last 100AH AGM battery died when I brought it home after a trip deeply discharged, put it in the garage, plugged it in to charger/tender and neglected to notice power strip I plugged into had been turned off, I was beat from a long day on the road.. didnt realize for a few months because that was the last trip of the season, then no amount of time on the charger would run the fridge for more than half a day or so.. when it used to do two days pretty easily on its own.

Knowing how much runtime you got is critical with a fridge, if you keep perishables in em.. for me its beyond mission critical because I need to keep medications cool.

I work in Dove Valley, so I could take yeh up on a beer.

The voltage stayed at 12.0.....no change after "reconditioning" efforts.

I don't really run anything else off the aux battery set-up so the fridge is the only draw and I've had good luck so far.

Currently re-working the system to include Blue Sea fuse box and a switch panel to support some LED lights.

Thanks for the help.

 

[Ducky's Dad]

We don't know the details on the battery. We don't know the details on the charger. We don't know if that "smart" charger is smart enough or big enough for that battery. We don't know enough to have an informed opinion.

 

[luthj]

Charge at 14.4v for 24 hours. Let rest overnight, test voltage. If it's at least 12.5v, do a load test.