Battery Charging Question

[Juan Grande]

I had my starter battery on a 10 amp charger last night and forgot to take it off before I went to bed. It was on there for almost 12 hours and the charger does not have an automatic shut off.

The battery was pretty drained when I put it on there, but I'm wondering if I did any damage by leaving it on there so long?

[eyebjim]

My guess it that it should be fine. I have regularly charged starting type and deep cycle batteries for 12 or more hours with no problem before I got a good charger. If you left it on for more than a day you may have an issue. Check it for fluid to make sure none boiled off. If it is low add DISTILLED water.

[Surface Tension]

It might not have automatic shut off but most will taper down to nothing. Still you don't want to boil a battery. Check the fluid levels.

You probably did more damage by draining the starting battery.

[Juan Grande]

Yeah, I'm not sure why the battery died. I was fishing and I went to turn the motor over and nothing. I ended up hooking it up to one of the deep cycles.

I charged it when I took it out of storage for the winter, but I guess not enough. My LMS-332 runs off the starter and must have drained it down. I haven't had my outboard running much this spring to charge it back up while on the water.

How will I know if the battery is toast? It won't hold the charge for as long as it should or what?

[Whoaru99]

That's one way.

Another is to have it load tested.

[Tom7227]

Take it out and charge it up. Check the voltage after you've charged it and then let it sit for 24 hours and check it again. If there is a drop in voltage there's a problem. If it won't take a charge about 12.4 volts you have a problem. Before you dump it do as Whoaru99 suggests and have it load tested at a garage.

[Whoaru99]

Well, you have to be a little careful on checking the voltage.

Normally, the battery will come off a charge and hold a high surface charge. This should be burnt off by applying a light/moderate load for a couple of minutes. Then, let the battery rest for 15 minutes or so and check the voltage. In a perfect scenario, it should be around 12.6 volts after this type of cycle.

[BobT]

That's a good point. Even a rather low charged battery may show good potential without a load applied. Best to test under a load. It doesn't take much load to show a problem either. A light bulb might be adequate.

Bob