SLA batteries bloating up - damaged ?

[dragonfire]

So i checked my 4 sla batteries ( bb hr9-12) and found one bank of two is much hotter than the other one and the cells within the case are bloated up like the shirt of "hulk" in the process of turning green..
.
I swapped them over with the same set on the other side but still these both get way hotter ( 55-60 degrees celsius) and on recharge and the charger seemingly does not ant to go into trickle charge like reularly in after 12-16 hrs.

they still deliver, though.

my question is, are these broken/ damaged cells and should i replace them ?


i was unable to find something in the manual o bb-batteries.com about this, but the second pair behaves totally different in meanings of heat ( barely handwarm, approx 25-30 degres celsius) and bloating ( no bloating) so i am unsure if this behaviour is still in the ok range or a sign of damage ? since i swapped sides i should have sorted out charger/ wiring related problems.

 

[Lessss]

The bloated ones have been over charged. use a 12V charger to charge each battery individually.
They are probably toast but use a 12V car light and a volt metert to see if they REALLY sag under load.

Cheap NiCd to build a replacement pack
http://www.northerntool.com/webapp/wcs/stores/servlet/product_6970_334925_334925

 

[nineball]

Overcharging ...but prolly due to a shorted cell...bye bye...time to upgrade

 

[dragonfire]

it evolved from one batterie + one pack of the second batterie and now both packs are balooning, i disconnected these and only charge the other both which now start to get warm ( but not hot).

i blame a deep discharge state when receiving them shipped+ positioning hindering the valves for that, maybe also user error by overriding the charger cutoff somehow by un- and replugging the charger when it was in trickle in order to "top off" the batteries.

i am still somewhat torn in between 12v23ah yamaha sla batteries ( 4 at 100€ plus shipping), dewalt a123´s ( i will want in between 16 and 64 cells at approx 4€ each), both can be handled by my charger except the balancing on the LiFePo a123´s - do they actually need active balancing or would balancing the packs ( 8s2p) on themsleves be sufficient, and can someone recomment a good undervoltage protectioning cutoff switch i can solder on each pack ?

 

[Lessss]

SLA should not get hot when charging. If they are you are boiling the battery and damaging it.

Charge each 12V batter separety and test each under load for sag. They sag recycle them.

 

[dragonfire]

two of the 4 batts are shaped in a fashion i am allready sure they will need replacement ( the deck doesn´t fit back on), the other 2 on charge went over 55 degreees celsius and started to bloat in after only 2 hrs of separate charge ( from cold to builing hot in 2 hrs).

Is this a sign of old batteries that allready overcharge before reaching cutoff voltage or is the charging controller damaged ?

i´ll check the output of the charger and most probaly unmount it to make a visual check for damage, this 2007 sla cells ( the recent last 3 cycles went through fine, incl total deplating in after getting designated range) will remain with me for a brushless outrunner project and general testing purpose. Should i go SLA again or try recycled a123 of higher total capacity instead if the price point is similar ?

 

[Lessss]

Anything is better than lead if you have the $$

Sounds like the SLA are DEAD
typical use lifespan on an e-bike is about 3 yrs.

 

[monster]

are you running different AH batteries in series?

i had some lead batteries that ballooned because of over discharging. i didnt capacity match them with some other batteries that i had in series with them.

 

[D-Man]

What kind of charger are you using? Amp rate?

 

[dragonfire]

What kind of charger are you using? Amp rate?

it´s the onboard charger of which i can´t find details specs ( ESR750ex goped), but i believe i read it used 3 steps charging 1c, 2c and 3c ( could also be 1,5 10 ?) only, the heating effect does not quite reflect that.

the charger was originally constructed to run on 110 volts 8 up to 240...), maybe the german 220+V are a tad too much or simply the batteries too old to be fully charged according to specs the charger uses.

i wonder if the batteries themselves have a builtin cutoff protection or if this is solely done by the controller, cause 2 batts are seemingly still alive but the bloated two only seem to prolongue range a slight tad on the lower draw range - range until the controller indicated "yellow" reduced by plain half, but the time in yellow was longer than regular until "red" ( gladly may way this morning led me along a tram-track so i was safe to try out range), actually it remained yellow for more than 40 minutes until i arrived.

i´ll most probaly use the two bloated one´s with supposedly 80% of damage for a test setup, the still working 2 others will nicely fit a buldup i should finally face to realize ( since i do weight 130 lbs only a 250 watt outrunner on high rpm´s and at 24 volts should be nice, simple and chap to built and thanks sla-batteries save to go out from with charger/ controller/ regen build attempts.

 

[D-Man]

Which part of the battery's are bloated? Top or sides?
I have 2 sla's with weak cells that heat up on the sides but don't bloat during discharge. The voltage rebounds to normal when hooking up the charger. Maybe yours aren't. Also, I believe those BB Hr series batteries have special "doping" that makes them out-perform all other sla's of that size. Thats why BB battery won't give you any data on the amount of cycles or life they have. Unfortuately, from what I remember, the ESR scooter is a higher amp scooter and thats why they come with those BB Hr9's. I've seen them pretty cheap somewhere.

BB HR9 $20.99
http://www.zbattery.com/Batteries/List-of-All-12Vs

 

[dragonfire]

Which part of the battery's are bloated? Top or sides?
I have 2 sla's with weak cells that heat up on the sides but don't bloat during discharge. The voltage rebounds to normal when hooking up the charger. Maybe yours aren't. Also, I believe those BB Hr series batteries have special "doping" that makes them out-perform all other sla's of that size. Thats why BB battery won't give you any data on the amount of cycles or life they have. Unfortuately, from what I remember, the ESR scooter is a higher amp scooter and thats why they come with those BB Hr9's. I've seen them pretty cheap somewhere.

BB HR9 $20.99
http://www.zbattery.com/Batteries/List-of-All-12Vs

the other diameter and top/ bottom seems to have expanded in a fashion that they won´t go back to regular shape ( or even close to) as it seems.
on the now running charge the batteries remain at slightly increased room temperature, i´ll see how that ends up as i will run this batteries again over the weekend ( there´s also a cutoff protection and the banks are in parralel anyways).

As for replacement batterie, as i do live in germany the discounted american offers ( like 2.99 on a batterie pack or 20.99 on said batterie) end up more costly than local sources most of the time; i may get these yamaha sla/gel 12v-23ah cells at the same body size at 25€ per piece ( or better said clunker), just there´s no info about their discharge characteristics, either, and meantimes get a dealt-packs a123 setup soldered and unvervoltage cutoff switches sourced ( 8s-packs or paired 4s-packs to get 32-48 fitted in the battery compartment are scheduled, mabye a 3s1p booster pack on a serial connect switch).

This only encourages me to go ahead with plans about that.

 

[scoot]

Hi DF

I have similar performance symptoms on one of my ESRs, just not the swelling batts. Turns out i think one of my SLAs is damaged... concluded that from measuring voltages after a "heavy discharge session" and how my flux capacitor lights were behaving and my CA was giving some irregular voltage readings. Well anyway, I am going to get a CBA II to evaluate all 12 of my SLAs so I can match them up for the 2 scooters I am using. It will also come in handy when i go for the lifepo4 batt project later this year. been reading up on the a123 conversions and learning a lot, but I am looking at the larger format cells like the headways and the BMI cells... will eventually start a build thread to hopefully get some support from all the wonderfully talented folks on this forum. see ya around

 

[dragonfire]

Hi scoot,

the BMi´s are appealing to me, too, but i figured the space it requires tomount them and the fact they all have to be mounted without actual contact and will want a balancer 8 so the packs will not utilituze the available space as good as lifep´s of 123 in cylinder form made me to tend towards a a123 pack, mostly cause they used dewalt-cells are available at 10% the price of a new bmi cell ( allthough the BMI´s have twice the voltage per cell and can take higher draws per cell) and packs up to 4 of them will go without balancing at all.

by next year the patents of life and lipo batterie usage in cellsize "d" and bigger will run out and they will be more commonly available, so some more moths waiting could get us a whole range of new batterie types in sla seize.

Another plus of the a123 cells is that they will work with the onboard charger, the bmi´s in series at 14+ volts ( allready 7.2 volts per singular cell) will require another charger than the allready existing onboard charger.

 

[heathyoung]

Bloated cells are damaged. May as well toss them out. Charging SLA's in series is usually bad news, I decomissioned a pair of 10/15KVA UPS's that used a series string for charging - straight rectified mains. 340V DC (eeek!) across 8 paralleled banks of 24 7.2 SLA's (14.3V) and no balancing/BMS apart from constant current/constant voltage profile. It worked fine for a while, but as the batteries aged, some cells would get high resistance, and so would get charged at a very high voltage - seen charging voltages as high as 35V across a 12V SLA, that entire battery block swelled so bad that it warped the outside of the UPS case.

These were not cheap batteries either - they were high rate CSB AGMs, but the extra heat at the top of the ups aged these batteries faster, the ones at the bottom of the case are still pretty good shape - resting voltage after 12 months - top batteries - 0-6V, middle 6-10V, bottom 10-13V. Anything under 12V resting went to the scrap metal merchants. A discharged SLA thats been sitting is a boat anchor.

There are simple shunt regulators that work well as crude BMS's on series charged SLA's - the new UPS's installed have the batteries in a separate case (so there aren't temperature differentials) - a shunt regulator system on 150(ish) 200AH 12V AGM batteries isn't feasible I suppose!

 

[D-Man]

Bloated cells are damaged. May as well toss them out. Charging SLA's in series is usually bad news, I decomissioned a pair of 10/15KVA UPS's that used a series string for charging - straight rectified mains. 340V DC (eeek!) across 8 paralleled banks of 24 7.2 SLA's (14.3V) and no balancing/BMS apart from constant current/constant voltage profile. It worked fine for a while, but as the batteries aged, some cells would get high resistance, and so would get charged at a very high voltage - seen charging voltages as high as 35V across a 12V SLA, that entire battery block swelled so bad that it warped the outside of the UPS case.

These were not cheap batteries either - they were high rate CSB AGMs, but the extra heat at the top of the ups aged these batteries faster, the ones at the bottom of the case are still pretty good shape - resting voltage after 12 months - top batteries - 0-6V, middle 6-10V, bottom 10-13V. Anything under 12V resting went to the scrap metal merchants. A discharged SLA thats been sitting is a boat anchor.

There are simple shunt regulators that work well as crude BMS's on series charged SLA's - the new UPS's installed have the batteries in a separate case (so there aren't temperature differentials) - a shunt regulator system on 150(ish) 200AH 12V AGM batteries isn't feasible I suppose!

Mmmm. I wonder at what point do they start bloating when getting old. Maybe more then 3 in series is bad with no balancers. Mine aren't doing it at 36v. If I go 48 volt, I'd run 2 chargers rather then 1. I know soneil makes a 72 volt sla charger. Sounds scary.

 

[Lock]

Pics would be fun. I have only ever seen bloated SLAs once... and they were split wide open. The EV was a "stair-climber" w/catapillar track designed to "walk" folks in wheelchairs up/down stairs. It had been plugged into a cheap charger and then forgotten about for TWENTY YEARS. Sorry I didn't take pics then. What is it that causes the swelling? Sulfate crystals just take up more room than constituent components?
tks
lok

 

[dragonfire]

this is the cells:



Funny how the "still good" cells go up to a similar temperature if charged without the bad packs, if all are charged together the bad ones heat up while the good ones stay cool and seemingly not charged (?), i´ll need to get measuring equipment for that at home.

 

[Lessss]

The bloating is pressure swelling from hydrogen offgassing. The hot gas softens and extends the plastic till enough pressure build that the vents release.

 

[Lock]

...enough pressure build that the vents release.

Or not. The batts I saw had large splits in their casings. I mean like 1/2" split apart...

 

[dragonfire]

i was hearing short and periodic "stem release" noises the charging cycle in before the swelling occured when walking by while charging. obviously the out-gassing is a sign of the cells being charged too fast and breathing out their life, in after they bloat up somehow. i hope to find time to make a run ith the bad block deattached and see the effective range reduction, as the batteries seemingly consist of blocks of 6 each and all have slight differences in temperature while charging ( and also bloating state) this could tell me ho well they still go.

As for splits´the case is still tight except around the connectors, there is a crack at both but no whatorever liquids coming out or being visible.

i believe the mounting in vertical doen´t help to gas them out and caused the ititial deformation.

 

[D-Man]

You need to get a voltmeter and check everything. Obvious some of the cells have failed and won't take a charge causing the other 2 batts to over-charge. Also, maybe the charger isn't working properly and putting out too much voltage. How old are the batteries?
Also, agms are much more efficient then flooded and don't need to be kept connected to the charger for days. Overnight is ok once in awhile, but these things hold the charge for a long time.

 

[vanilla ice]

Is there any reason to disconnect "smart" SLA chargers? The only time my SLA's leave the chargers is when they're getting ridden. They've been fine for years this way. The only time I've seen bloated SLA's is on some UPSes with old batteries.

 

[D-Man]

Yeah, extra money thrown away on the electric bill for no reason. It would be ok if your using individual 12 volt chargers or have balancers. But if you take a voltmeter and watch the voltages for longer strings in series, there not the same when sitting on float. Some high, some low depending on battery age. The higher the voltage, the more they fizzz. Will they dry out premature and fail is the question. I just don't like a charger attached to a battery when I'm not around or sleeping. I don't care how "smart" they think it is.

 

[vanilla ice]

Maybe I can find a timer to put between the outlet and power strip. I don't charge in the house.. there's no freakin way I'm rememberin to go out to the shed 8 hours after every ride to disconnect the plugs. These are slooooow chargers. Wait.. then theres the issue of unplugged chargers back draining the packs right.. :lol: