I have a car wintering in an extra garage when I thought I would check the battery. Upon opening up the cell covers, there was ice in 3-4 of the chambers. I charged it up, and the ice disappeared. Was that ice in a discharged battery a bad thing, or doesn’t it really matter?
The ice may well have damaged the plates in those cells. However, if the ice had only formed on the surface, it should be okay. A load test is in order.
BTW, NEVER try to charge a frozen battery! It can explode. You were lucky this time.
You got ice because it was a near-dead battery. The ice might have done some damage by expanding inside the plates. You’ll see when you try to use it in the spring.
The slushy looking ice appeared to be just on the top. Is that right, even with any ice the battery might explode when charging it?
No, it probably won’t explode under those conditions. But the electrolyte may be shot out if the rate of charge is high enough.
And since it wasn’t solid ice, the battery will probably be okay.
Thanks for the good info. I guess I’ll keep a closer eye on all of the batteries I’m not using in the winter.
If it happens again, take the battery out, warm it up before charging.
I hope the battery is not touching the bare floor. A battery on the ground is a battery in use and will discharge. If you go near one on a concrete floor, wear eye protection. The battery will be unpredictable (you don’t know if it will explode, it usually doesn’t, but you don’t want to be standing over it if it does). I’m not brave any more. Sorry, the battery is probably still in the car.
The old battery on the floor problem disappeared years ago with the advent of different materials. Of course the new materials does not proven potential temperature problems when the floor is colder than the air.
Frankly I suspect you are due for a new battery. Have it checked at your local part's store. It usually is free to get tested and they are usually good honest test. How old is this battery? Discharging a battery is hard on it and it sounds like between being stored discharged and likely old age, it is not very good anyway.
Ice in a battery = A dead battery that will never hold a charge. The battery requires replacement.