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Since the river has been so low here, I have had my boat in the yard for a month or so. As I went out to do the maintenance change on the batteries today, I ran into a problem. While the regular wet cell trolling motor batteries just needed topping off, when I hooked the charger up to the Optima starting battery, it went of the scale at 6+ amps !
And this was only on 2 amp charging rate on the charger. I tried my other charger, checked to be sure it wasn't on 6v and still the same high rate. The battery still had some juice, as it could lift the outboard up and down -- so I guess there is not an internal short, but I could tell it was weak. I unhooked it from any boat wiring and it was still charging at 6+ amps for an hour or so. Finally after a couple of hours it is now charging at 3 amps.

I have not had one of these type batteries before. It is possible the radio or clock or something has been left on for the last month, as it was sure not acting this way 45 days ago out in the Gulf for scalloping.

Is the battery toast ? Or should I just keep on charging it? With a regular wet cell battery, I would expect charging amps to go down to near zero when charged. Is this what I would expect with an Optima?

It is suppose to be charged at 10 amps - I believe. I always disconnected mine after a charge, do you have a main battery switch?

Chalk wrote:It is suppose to be charged at 10 amps - I believe. I always disconnected mine after a charge, do you have a main battery switch?

I had heard these batteries were different, but I don't understand much about them. A normal 10 amp charging rate would probably explain how it could suck so much amperage out of my fairly standard 2amp/6amp trickle charger. Charging got interruped by a thunderstorm yesterday, but I will continue charging this morning and see if it does OK. The fact that it is taking a charge and getting stronger is making me think it is not a bad battery.

Yes I have a battery main switch and I saw yesterday that I had accidently left it on for a month. While I am pretty sure all the electronics were off, but since I didn't wire this boat, there may be a "slow leak" of current somewhere. I agree it is good practice to turn it off when you store the boat. Thanks.

Mine charge at about 10 amps. One thing about the optimas: tell them it won't hold a charge and get a brand new one. Warning: Do not try to fast charge those suckers. You can boil it over in a heartbeat.

Thanks for the info, my optima charged back up ok on a trickle charge, although it did charge at a lot higher amps than a normal battery. It just ran down because I left the radio on I think, not a bad battery.

I purchased one of those chargers with a coil battery setting and computer control. Cost about $60 bucks and it works on my optimas like a champ.