Bad charger or battery?

[Cicada]

Two summers ago, I purchased a deep cycle gel cell battery for my trolling motor. I can't get it to hold a charge even when new. I put my Schumacher 2/6/10 amp charger set on the AGM/ Gel Cell setting on it set to charge at 2 amps. If the charger tells me it is fully charged, I can disconnect the charger and immediately hook it back up and it will read less than 12 volts and something like 9% charged. Sometimes, I will see a flashing "check" light. If I take the boat out, I can get about half a day on the trolling motor. Any thoughts? Am I doing something wrong? Did I get a bad battery? Bad charger?

[Powerstroke]

Sounds like a problem I would've addressed two years ago. Only true way to tell is with a volt meter or multimeter to test the actual voltage. I never trust the readout on the battery charger.

Either that or take it to someplace that deals with batteries. They can put a load on it and see if you've got a bad cell or something.

[Surface Tension]

There isn't any good reason to charge a deep cycle at 2 amps. Set it to charge at 10 amps, it'll taper the charge rate down on its own. A 115 amp hour battery would take at least 2 days to charge and thats if it charged at 2 amps which it won't.

2 amp charger is for small batteries like a motorcycle battery and to maintain batteries. In fact a stand alone 2 amp charger will state not to charge batteries with it, only to maintain them.

A good battery doesn't need to be maintained in that way, not that you shouldn't but I don't like a battery hooked to a charger and left. Too many bad things could happen. During winter I'll put a battery in storage on the charger maybe once every two months. If it takes any longer then 10 minutes to come back to full charge the battery is questionable.

The smarter some chargers get the more persnickety they get.

Best charger for a deep cycle is a charger that specifies it as a deep cycle charger or a setting for deep cycle.

If you put a new fangled/smart automotive charger on a deep cycle battery you can get results like your getting. For now try and charge it at 10 amps and see if you get an error.

[h8go4s]

Frank is right, and by now you may have done some damage to the battery. Charge it at 10 amps and if that doesn't work, get the battery tested.

[CaptainMusky]

Connect the charger, plug it in and take a reading while it is charging the battery.

I have heard of some guys having trouble getting Gel batteries to charge, but your charger has a setting for that so I would think it would work. But agreed, 2 amps it too low of a setting. Run it on max. All these chargers these days are "smart" chargers and will only push in what the battery needs.

[gunner55]

Don't trust the readout on your charger.We have a Schumacher "smart" charger & we can plug it in,it will say 12.6 volts or 65% charged.As soon as we unplug it & plug it back in,the readout changes,more in line with what our maximizer on our MK says.We also have a loadtester to check our batteries,it's just a cheapie from HF but it has come in handy more than once.Frank & PS both are steering you in the right direction.