FLA Batteries heating and boiling

[Berseker]

I have 4 x 12v 220ah luminous fla batteries, that have served me since 2016. they are hooked up to a mustpower 48v 4kva inverter, on charge settings 58v absorb and 53,2v float 23amps max charge current and i manually equalize @ 61v for some hours every month or so, am partially offgrid. recently i noticed that they are getting unusually hot during absorb charging and boil/bubble moderately as well, making me double check to be sure i didnt mistakenly leave it on equalize.

some cells have the electrolyte a bit discolored, while majority are clear as plain water. i also notice some cells go down and need topping up more frequently than other cells, within 2weeks versus 5 to 8weeks for other cells.

i reduced the charging voltage to 56.4v adsorb and 53.2v float, and it didnt get as hot as it usually gets, however noticed a drop in battery performance, as voltage quickly dropped to 49.2v underlslight loading , instead of the usually 49.6v after 3 to 4 hrs under the same load

Has anyone experienced this, and any possible remedy?

i am thinking along the lines of draining the whole electrolyte, cleaning the internals of the battery, by flushing water through it, and refilling with clean good electrolyte. however i have heard of many horror stories of folks whose bank failed instantly or went steadily down hill after such an attempt.

waiting for tips/suggestions on what to do next

 

[nosys70]

the problem is if you just provide the bulk voltage to a string of cells, there is no reason that each cell will charge the same.
At best when cells are new, they look all the same (will have the same internal resistance), but even there it is a bit of gambling.
with time, the only thing that will happens is each cell will diverge from the others (especially FLA).
That is why a BMS is almost mandatory.

 

[gnubie]

Are the battery cases translucent? If so shine a light through them and see how much buildup there is at the bottom of the cells. It may just be a case that they are EOL, with some cells having failed completely. The discolouration is interesting, cell contamination? Is it coloured or is there just fine material suspended in their? Fine material floating around says it's game over as far as I can tell.

 

[Berseker]

Are the battery cases translucent? If so shine a light through them and see how much buildup there is at the bottom of the cells. It may just be a case that they are EOL, with some cells having failed completely. The discolouration is interesting, cell contamination? Is it coloured or is there just fine material suspended in their? Fine material floating around says it's game over as far as I can tell.

The case isnt translucent.this discolouration appears grayish in colour, like dissolved lead...ouuch, game over stuff right?...

Had an HA02 balancer hooked up before ,but removed it after a while as i felt it wasnt necessary for an FLA bank equalized monthly.

Guess will ride it out till it quits, was hoping to hit the 6 year mark with them.

As per build up, observed some build up on the side top plates in a few of the cells, soft mushy stuff

 

[gnubie]

Yeah, grey doesn't sound promising, same with the build up at the top of the cells. I had a HA02 across a couple of mismatched (age) AGMs, did the trick nicely and kept them no more than about 30mV different. Without it one would regularly go up to 15.5V during charging.

 

[Silentpower]

I used to look after milk floats which were powered by 36 400ah 2v cells. First sign of failure was warm cells. When they get older, plate resistance is not uniform across the surface and this causes localised heat. The effects of this is to slightly buckle the plates, shedding some material in the process. This discolours the electrolyte. Varying resistance between cells exasperates charging in balance. I wouldn't recommend changing the electrolyte because getting the specific gravity correct is very difficult and will depend on the state of charge before the change. Also, the plates oxidise very quickly when exposed to air. I'm afraid to say, it sounds like the horse has bolted. Re equalise. It's a necessary evil. It's best done when needed, ie, you do your scheduled maintenance with a hydrometer and only equalise when those readings are out. Equalisation stresses the battery so only should be done when really needed.

 

[Berseker]

I used to look after milk floats which were powered by 36 400ah 2v cells. First sign of failure was warm cells. When they get older, plate resistance is not uniform across the surface and this causes localised heat. The effects of this is to slightly buckle the plates, shedding some material in the process. This discolours the electrolyte. Varying resistance between cells exasperates charging in balance. I wouldn't recommend changing the electrolyte because getting the specific gravity correct is very difficult and will depend on the state of charge before the change. Also, the plates oxidise very quickly when exposed to air. I'm afraid to say, it sounds like the horse has bolted. Re equalise. It's a necessary evil. It's best done when needed, ie, you do your scheduled maintenance with a hydrometer and only equalise when those readings are out. Equalisation stresses the battery so only should be done when really needed.

wow, not so good news i supz.

so i used a digital meter to check the battries, and 1 of them drops to 10v after a few hours of 300w load on them. i have 4 x 12v 220ah flooded tubular batteries. part of the options i was considering, you have just torn to shreds ..ie replace the electrolyte, flush the internals of the battery with clean water and refill with new electrolyte. i guess at this stage, i dont have anything to loose.


my 2nd option is to buy a single flooded battery and replace the battery that drops to 10v. i undertsand that it may be money wasted, as mixing old and new batteries isnt a good idea, however, i dont readily have the funds to replace my battery bank now. the other batterys also get hot during charging, am wondering if they are almost dead again, or their being hot is caused by the 10v battery in the mix, and they would revert to their good ol cool running self, once the bad battery is removed

 

[Zil]

Old batteries fail. Our first set are for learning. Test each cell with hydrometer. Remove bad battery. Plan on new bank.

 

[Berseker]

Got a similar used fla battery from a pal, will use it to swap out the bad battery, and see it how goes. intend to go LIFEPO4 whenever this bank goes south permanently

 

[softdown]

10 volts definitely says bad battery cell to me. Can you check the batteries resistance? The SG should be off the charts low with a bad cell. I'd replace that battery. My first battery bank was not high quality - I had to replace a battery 1-2 times/year. It wasn't such a big deal. Of course many installers prefer to replace the whole bank. Then sell the good, used batteries to the next chap. Making money hand over fist.

Equalizing for "hours at 61V every month" seems a wee bit aggressive to me.

I find the healthiest cells always use the most water.