Batteries are very warm

[c130king]

Another question I hope some of you can provide some clarity on.

I checked my voltmeter at the electrical panel to see what the voltage reading with batteries being charged by the battery charger on shore power. Meter was reading approximately 13.5 volts.

So I opened up the battery compartment to use my new digital voltmeter and check the voltage directly at the battery. The compartment lid was very warm. Batteries were very warm. I had some "boil over" (I think) on a few of the cells (2 x Type 4D batteries).

My new voltmeter read 13.35 with battery charger running. No DC load at the time. Everything was off except the bilge pump which wasn't running. Batteries had been on charger for about 24 hours.

I turned off the battery charger so they will sit overnight and I will check them again tomorrow. Did not check fluid levels today. Figured I would let it cool down. Monthly maintenance checks on 3 May and fluid levels were all checked with a few being topped off a little. Specific gravity was checked on all cells and the needle floated up in the "good" (blue) area for all 12 cells.

Does anyone else notice their batteries and battery compartment feeling very warm while charging on the battery charger?

Any clues here that would point to anything I should look into? I do have a couple of boat maintenance and electrical system maintenance books which I am digging out as soon as I hit submit.

Thanks in advance for any help with this issue. And I have another issue...for another post...on leaky stuffing box nuts...but I will hold off on that one until I take another attempt to tighten those nuts down.

Cheers,
Jim

 

[c130king]

By the way. I did check the voltage after turning off the battery charger. Put a quick load (frig, lights, nav/comm) on both batteries for about 1 minute. Then checked voltage and got 13 volts.

 

[Witzend]

How old are they?
Probably out gassing, as they age, the Voltage that out gassing occurs drops.
I just replaced my 8yr old 4Ds that would do the same even though they seemed to hold a charge for a brief period... never really bothered to test them...8yr is outside the normal lifespan.

 

[iSailor]

How old are they?
Probably out gassing, as they age, the Voltage that out gassing occurs drops.
I just replaced my 8yr old 4Ds that would do the same even though they seemed to hold a charge for a brief period... never really bothered to test them...8yr is outside the normal lifespan.

8 years, uh oh, mine are original (2001) . I guess I will add them to the "watch" list for replacement.

 

[c130king]

Mine are 8 years old. Left charger off overnight...about 20 hours. Voltage was 12.6 when I got back to the boat. Turned on frig at low power and 12-volt fan and stereo.

Was under 12 volts (11.95) in about 2.5 hours. That doesn't seem right to me.

I think the capacity of the batteries was more affected from the "complete drain" that happened about 6 months ago then I thought they were. They seem to be fully charged in terms of voltage...and specific gravity seems to be fine...but they just don't last very long.

Time to go price some new 4Ds.

Cheers,
Jim