battery boiled dry

[jatnip]

I have 8 -6 voilt batteries hooked up for 12 voilt system.  Was chargeing batteries and either the batteries was dry or the charger did not stop charging and boiled all batteries dry.  Voilage was 13 before water was added and after adding water it was 12.8 voilts.  Added water and seems to be OK.  How much damage do you think was done?  How offten should you check water in the batteries?  Thanks in advance, Jim

[FloridaCliff]

Jim,

A couple of questions;

How long were the batteries on charge?

What type of charger are you using?

Cliff

[jatnip]

Bateries were on charge about 48 hours.  The charger is an inverter/charger.  When I noticed it the charger's cooling fan was still running so I am thinking it was still chargeing.  Jim

[FloridaCliff]

Jim,

Thats a long time to still be charging.

I would be leaning to the batteries already being dry or close to it.

I am sure they have suffered some damage, but how much is hard to say.

I would top them off and monitor the situation to see whats happening.

Check them every couple hours, verify how much voltage the charger putting out.

Put a load tester on after they have been charged up and test each battery.

HTH

Cliff

[pvcces]

Jim, usually, the batteries are boiled dry by charging equipment that does not monitor temperature. When the batteries reach full charge, most of any charging power still going into the batteries starts turning into heat. If your inverter has a temperature probe for the batteries, it should be able to minimize any overcharge.

What you ran into is real easy to have happen if the batteries are in a very warm environment. By the same token, if the batteries are very cold, the voltage must be pushed up quite a bit to get a fairly rapid recharge. Charging voltage really IS dependent on the temperature of the batteries.

Your inverter will be able to give you a rough idea of the capacity your batteries have left. As long as the low voltage cutoff is set at 10.5 volts, and you start from a full charge, put a load on the of roughly 1/20 of their rating in amp hours on them and observe when the inverter shuts itself off. The number of hours times the amperage of the load will give you the amp hours that you can actually take from them.

You should not do this frequently, because the testing will cut into the life of the batteries; you should limit your discharges to around 1/2 of the capacity of the batteries.

Good luck.

Tom Caffrey PD4106-2576
Suncatcher
Ketchikan, Alaska