Deep Cycle/Bank Charger Question

[Juan Grande]

Got another battery question for you guys.

I have a newer boat (2005) and I have two deep cycles with an on board bank charger. The batteries have been losing charge/power way quicker than they should. I had them fully charged and after about two hours of trolling motor use, they lost about 1/2 to 2/3 of their power. They eventually go completely dead.

I suspected one of the batteries was bad so I brought it in to the marine place and they swapped a new battery for it. I hooked up both batteries at full charge, didn't use the boat, and when I check back the new battery was dead.

My bank charger has a row of lights for each battery that shows how much charge is on there. I was told (by the dealer) that if one light is blinking that the battery is either completely drained and won't charge on the bank chargers or their is some other problem.

Is it possible that the bank charger is defective and is somehow draining the batteries when they're hooked up? I've checked all my switches an nothing is left on.

I did notice this time that only the right battery was completely empty, the left one still had about 75% juice. The right battery is the new one so I'm assuming it's not bad. The wires are all hooked up correctly.

Any ideas as to what could be draining the batteries when they're not in use? Also, why am I getting such short life on them when out on the water?

Thanks in advance for your help.

[Scott K]

The best way to test this is to hook up an amp gauge in series with one of your battery cables and see if there is indeed a draw from the battery, if there is start unplugging things that are hooked to your battery untill the draw is gone. Or just charge the batteries, then unhook charger and see if they last longer, if it does then you know it is the charger.

[BoxMN]

Also, check for a blown fuse in one of the two charger leads. This happened to us not long ago. So only one battery was actually charging, and then you would have one battery powering your motor = short charge life. This in turn hurts the one working battery.

Also check the water level in the batts. Need to be just covering the lead plates, not more, no less. Also, you get best performance when you replace both batts at once when you have a 24v system. Good luck,