Battery charger/battery problem???

[Scoot]

I just put all new batteries in my boat this spring (two for the 24v trolling motor and one for the starter). I've got an on-board charger that juices them up after each use. When I plug it in, it charges them up fine (as indicated by the indicator lights saying that all three batteries are fully charged), but after I unplug the charger, 24 hours later it reads that all three batteries have a half charge. I've double checked to be sure that nothing it turned on in the boat to drain battery. Do I likely have a bad battery? Is my charger likely reading goofy? What's up?

------------------
Scoot

RodsbyEngel: custom made fishing rods

[IFallsRon]

Indicatior lights are notorious for their failure rate. For an accurate reading, get volt meter.

[Scoot]

Thanks IRon. I've heard that too. The thing that troubles me is that it reads full charge at one point, then drops down to half charge. This happens each time I charge the batteries. Doesn't seem like innacurate indicator lights to me, but maybe that is the issue.

------------------
Scoot

RodsbyEngel: custom made fishing rods

[IFallsRon]

There's a meter-type indicator on my camper. It'll show no charge yet the lights will work.

I can have it plugged in for a week and by the end of a day the meter drops dramatically from full charge.

Also, these type of batteries seem to have a short life. It hasn't been unusual for the batteries I use to have a dead cell. I've had car batteries that have lasted for years inspite of my efforts to ruin them.

[This message has been edited by IFallsRon (edited 06-07-2004).]

[who are those guy]

Every once in a while - drain all your batteries dead as dead and recharge. This helps quite a bit in adding capacity and life to 12V. I just leave a light attached overnight to drain fully.

[Giant_Jackpot]

Scoot,

I agree that you should get a voltmeter to know for sure. Radio Shack has digital meters that are not too expensive ($15-$20). After the charger is unplugged for 24 hours you should have over 12.5 volts on the battery. With your on board charger plugged in and showing full charge you should see about 13.2 volts at the battery.

I am curious why you are unplugging the charger. The on-boards are designed to hold the “float voltage” indefinitely with no harm to the battery. I would leave it plugged in until you are ready to use the boat.

[Scoot]

Yeah, I know you're supposed to keep them plugged in. However, I store the boat in my garage and it gets really hot in there. The charger gets a little warm when plugged in for a long time. So... I unplug it so it doesn't get too warm. Probably not necessary, but I prefer to do it to avoid any potential problems.

Thanks for the help guys. I'll get a meter and check it out.

------------------
Scoot

RodsbyEngel: custom made fishing rods

[Tom Wilson]

I didn't see what kind of charger you've got on this thread, but I've worked with these things and sold them for some time, and frankly some of them are not up to par. I also didn't notice whether this is just an issue of the meter telling you they are depleted or whether the batteries are actually losing power. It is possible that the unit has developed a ground issue or short that is actually draining your battery. I can charge mine on monday and not use it till friday and I have never had a drainage issue. If you bought three brand new batteries you should not be getting drawdown. If it were a battery issue they would not charge to full in the first place--the charger would run continueously in order to charge that bank. It is also possible that you don't have enough charger to get the job done. You need at least ten amps per bank to charge large batteries. Smaller trickle chargers over time will not continue to give good charges as there is not enough power to clean the plates before they charge. The last thing I would say is that if its a minnkota charger--just go ahead and replace it.

[Giant_Jackpot]

Letting lead acid batteries go “dead as dead” is NOT a good idea. Go to any battery manufacturers web site and they will tell you that fully depleting them is one of the worst things you can do for battery life. Even if you only use them for an hour, you should charge them up as soon as you get home. Nickel Cadmium (NiCad) batteries are the ones that like to be fully discharged.

[who are those guy]

This is why I dont gamble, Jackpot. Thanks though. I will now have a few words with my old man.