Testing An 80Ah Deep Cycle Battery

[el_walto]

Here is the story:

- In June 2012 Bought a Trailer with a supposedly new group 24 Deep Cycle Battery (80Ah stamped on it, 2011 stamped on it)
- Used battery a few cycles.
- Accidentally left battery connected, Stupid CO/Gas Alarm drained the battery to 6.0V. Not sure how long it was sitting dead, but estimating about 30 days.

Charged battery back up with 2Amp charger.

What is the best way to test the battery capacity?

Is it OK to discharge it %100 to (10.8V) for testing if i charge it back up immediately afterwards?

I have bought a Hyperion 14s charger. If the battery was new, i should be able to discharge at 4amps for 20 Hours for %100?.

Any suggestions on best way to test? Is the battery likely now trash?

 

[el_walto]

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[999zip999]

You might read up on deslufator as these batteries can't be cheap. I like what the salesman says ?

 

[Grey beard]

A fairly new deep cycle battery should come back fine. RV and boats see a lot of completely dead batteries but even the most abused will last a couple years. Forgetting to use the disconnect happens to nearly every RV owner. Years of experience. Eventually we get better at it.

 

[dogman dan]

It should revive as said above. It's not a starter battery. It won't have liked it, as well as whatever may have happend to it in the past. So expect less than 80 ah for sure.

Testing it, it might be good to just discharge it to 12v, measure that, and then just call that your capacity even if it in fact has some more. Then aim for future discharges that are no more than 60% of that number. For longer trips, it's hard to beat a small generator to keep it topped up.

 

[el_walto]

I did a 4amp Discharge(Thinking 20Hour rate) to 10.8V and only got 22.2Ah. Graph is attached below. I was unable to find a discharge graph of a deep cycle battery on the internet, so hopefully this might help someone. Too bad I didn't do a full discharge when it was first purchased.

I plan on picking up a new 80Ah battery from Costco and will post full discharge graph for comparison.

So many people have opinions about what brand battery not to buy etc, but they never point me to any actual evidence that a Costco battery is any worse than a generic one from a dedicated battery store. It's all such a mystery, data sheets are few and far between.

2011(stamp) 80Ah Canadian Performance Series Deep Cycle Battery. Outputting 22.2Ah from full to 10.8V. Discharged at 4Amps(20 Hr rate):