Smokin’ Hot Battery

[TommyD]

I have an old 24 V System (12 x 2V) 850 Ah @ 20, however have noticed that the battery bank seems to need a change more often. Today, while charging, I noticed that one battery was 80C while all the others were around 40C. When I opened the vent cap, smoke was coming out.

Not sure what’s going on and suspect time for a new LFP Battery Bank and Inverter.

Any other thoughts, chance of “repairing” the smokin battery or just accept old age and move on?

 

[Hedges]

How does voltage compare? Specific gravity?

Possibly, the cooler cells are at low SoC and hotter battery is being over-charged. If that is the case, recharge lower one with by itself if you can. (but I think it is more common for a smaller number of cells to be undercharged.)

But I think 40C sounds pretty hot.

Can your system be configured to operate with 11 x 2V? (reduced voltages.)

 

[chrisski]

An 850 ah pack, depending on specs ahould be limited to 10% (or manufactuer spec) so less than 85 amps.

Can you pop the cap and look at the state of the cell compared to others?

A specific gravity test would determine if equalization is needed. This can only be done on Flooded Lead Acid.

If you saw smoking, I would not want to equalize the cell unless it was removed from the others and equalized in a safe place it could not burn the place down. I've also not equalized a single cell, but for me this would be done with my 10 amp power supply since my MPPT can't provide such a low voltage.

In the end, this may be a lot of work. If you wanted a lithium pack enough, this is a good reason.

 

[Mattb4]

Would need the results of voltage tests and SG test. However from the symptoms you have a shorted battery cell. Depending on its age and condition cast off materiel (hard sulfer, lead) builds up in the bottom of the cell until the plates short out. Even a partial short can lead to the cell heating under charge.

 

[seneysolar]

Plates exposed or submerged?

 

[v_green57]

I have an old 24 V System (12 x 2V) 850 Ah @ 20, however have noticed that the battery bank seems to need a change more often. Today, while charging, I noticed that one battery was 80C while all the others were around 40C. When I opened the vent cap, smoke was coming out.

Not sure what’s going on and suspect time for a new LFP Battery Bank and Inverter.

Any other thoughts, chance of “repairing” the smokin battery or just accept old age and move on?

Not rare with FLA. Internal plate short(s). Happens less with higher quality batteries with good QC like Deka and Rolls Surette.

The attached IR image is a bank of Costco GC2's (Trojan). Case temps on the obviously tanked one were 104F. Affecting the center and right cells.

At least FLA's have some recycle value...

 

[McKravitts]

If you are using lead acid batteries with a removable cap, than thay are FLA and water needs to be added about every 4 to 6 months.
Not doing so reduces the life substantially.
If you got 2 to 3 years out of them, consider yourself lucky and purchase LiFEPO4

 

[Hedges]

"2V 850 Ah"

Those are the sort of batteries that might be deep cycled daily for 7 years, or somewhat shallower for 20 years.

"old 24 V System"

How old are they?
Brand/model link to data sheet and manual?

 

[TommyD]

Thanks for the input. Batteries are over 20 years old and were well maintained by the prior owner and myself, however will now go forward and replace with LFP. Thought you might enjoy a video of the “Smokin Battery”, but it looks like videos can’t be uploaded

 

[v_green57]

D

Thanks for the input. Batteries are over 20 years old and were well maintained by the prior owner and myself, however will now go forward and replace with LFP. Thought you might enjoy a video of the “Smokin Battery”, but it looks like videos can’t be uploaded

Damn. 20 years. No wonder one of them gave up the ghost...