GBS 200Ah cells - Swelling/Bulging

[vburgh]

I acquired two "new," old stock GBS LFP 200Ah 12v packs (GBS LFP200Ah-A cells) primarily to learn and experiment with. They'd been sitting in their boxes in a pole barn in Michigan for an unknown duration, but perhaps 3-5 years. Pack voltages were around 13.14v when I opened them. I added a JK-B1A8S20P BMS to each battery, charged them, noted some drift in the cell voltages and so top balanced the cells in each pack. Both packs are yielding about 75%-80% of their rated capacity. As voltage drops, I have one battery with three cells that range together with one outlier that maintains higher voltage (vdiff= .366 near UVP disconnect); on the other pack, I have one cell that drops voltage faster than the other three (vdiff=.1 near UVP disconnect). No temperature or other anomalies during charge or discharge.

Both battery packs show swelling, primarily on the end nearest the POS (+) terminal. Swelling was present when I got the batteries, so it is not related to my charge/discharge (I charge to 14.1 with a Victron charger - no float - and a tailcurrent setting of 7.5A). Again, the batteries came to me unopened and unused, so - apparently - no prior history of overcharging. As I said, I acquired these cells to learn and experiment with, but my question is this: should I be concerned about the safety of the cells due to the swelling? I did do some reading on here regarding EVE cells and bulging, and it seems it's never good but not always dangerous. Anyway, curious to know what those more experienced than I think. I am attaching images for reference. Images show swelling and gaps between cells due to swelling. I appreciate your informed input. Thank you.

 

[wpns]

Doesn’t look that serious, how do they look at 0% and 100% SOC?

I’d be tempted to rearrange the cells into one good battery and one with two imperfect cells.

 

[vburgh]

Doesn’t look that serious, how do they look at 0% and 100% SOC?

I’d be tempted to rearrange the cells into one good battery and one with two imperfect cells.

Thanks for the reply. They are at 100% SOC in the images above. I'll discharge them and pay closer attention to their physical condition. I've considered your suggestion of making one good battery, but I was reluctant to release the cell compression for fear of making the swollen cells worse. Perhaps that's not an issue if I reconfigure them when they're discharged? I've also toyed with the idea of combining the two packs into one 2P4S pack so I can free up my second BMS for something else. I realize capacity would be limited by the outlier cells, but these are just for learning and experimenting anyway, so I could live with that.
Thanks again.

 

[wpns]

Thanks for the reply. They are at 100% SOC in the images above. I'll discharge them and pay closer attention to their physical condition. I've considered your suggestion of making one good battery, but I was reluctant to release the cell compression for fear of making the swollen cells worse. Perhaps that's not an issue if I reconfigure them when they're discharged? I've also toyed with the idea of combining the two packs into one 2P4S pack so I can free up my second BMS for something else. I realize capacity would be limited by the outlier cells, but these are just for learning and experimenting anyway, so I could live with that.
Thanks again.

AFAICT they expand as they charge, so if they go back to normal when discharged then they are probably fine

 

[Steve_S]

This setup sat around for who knows how long as you say, anywhere from 3-5 years and under what conditions (temp wise) again unknown really.... Seriously, each cell should be charged individually to 3.650V allowing charge to drop to 2.0A before disconnectimg charge.
Then set the cells in Parallel and charge the set of 4 again to 3.650 - till Amps drops to 2.0A again and allow to settle in parallel.
Now assemble the battery pack as normal with BMS, charge the pack to 14.2V (3.550vpc) and note what differentials the BMS shows between cells.

Set the JKBMS to start active balancing at 3.42 allowing for the default 0.010mv differential.
Also remember to calibrate the BMS Voltage so that the voltage at pack terminals (where your cables go) are set in the BMS Config screen. This can be done with no load or charge as a quicky. better calibration can be done with a Known Fixed load of 10-15A.

LFP cells need to be Fully Top Charged to active / reactivate the electrolytes within after 6 months of dead storage or just after manufacture (1st initialization). As those cells were still above 3.0V they are likely OK but do need a proper Top Charge.

For normal changing, Bulk/Absorb to 14.0V and float at 13.8V. Your EndAmps/TailCurrent is 10A.

NB: If presently "bound" and you separate them, you should have no issues. Do note that if reorganizing the cells & then re-binding them, that should be done when cells are at 3.200V & 25C Temp +/-5C. Hand Tight "light squeeze only" ! This is to prevent gas pockets developing within the jelly roll and pushing them up to the vent area. Gas pockets can make hot or dead spots affecting cell life & capacity. Too much pressure could result in popping the vent valve, ulltimately trashing the cell. Sadly much of this is lost on the folks who rush and look for confirmation bias as opposed to industry standards & fact.

Hope it Helps & Good Luck.
Seasons Greeting & Good Wishes included.

 

[vburgh]

This setup sat around for who knows how long as you say, anywhere from 3-5 years and under what conditions (temp wise) again unknown really.... Seriously, each cell should be charged individually to 3.650V allowing charge to drop to 2.0A before disconnectimg charge.
Then set the cells in Parallel and charge the set of 4 again to 3.650 - till Amps drops to 2.0A again and allow to settle in parallel.
Now assemble the battery pack as normal with BMS, charge the pack to 14.2V (3.550vpc) and note what differentials the BMS shows between cells.

Steve,

I appreciate the thoughtful and detailed reply. Thank you. I will give it a go and report back. Seasons greetings to you, too.

 

[vburgh]

AFAICT they expand as they charge, so if they go back to normal when discharged then they are probably fine

I discharged one of the packs. No apparent change in the cells' physical appearance.

 

[Sojourner1]

Do the cells have codes on them like these? I personally wouldn't seperate the cells. I'm 9 years into my gbs cells fulltime use. How are you going to use the batteries?

 

[vburgh]

Thanks for the input. Yes, mine do have labels. Is manufacture date decipherable from them?

I plan to experiment with them, mostly. I was thinking of a small basic solar installation at home just for kicks, but I remain undecided. Lately, I’ve been capacity testing the individual cells in one pack. Best is 174Ah, worst is 140Ah. The other two are around 160Ah.

 

[Sojourner1]

March 31, 2015

This March will be 9 years of fulltime use with over 3,000+ partial cycles ranging in 35-45% daily discharge and sometimes up to 55% discharge if using air conditioner. My lowest SOC has been 25% and still using high draw items at that state before solar starts to assist. System is on 24/7/365.

I can't turn my absorb off so it will go for about 7 minutes, set to 14.1v most the time but during winter I'll change it to 14.2v for mid December until beginning of February when the daylight get longer. Then back to 14.1v rest of the year. Floats at 13.6v. There's always something drawing on the batteries.

 

[vburgh]

March 31, 2015

Obvious enough now. Thanks for deciphering. And that explains a lot.

 

[Sojourner1]

I was editing my post during your reply.

 

[vburgh]

March 31, 2015

This March will be 9 years of fulltime use with over 3,000+ partial cycles...

Do you have any idea what your capacity is 9 years later?

 

[Sojourner1]

No, I'm sure something is loss maybe... but I can still use everything in the 5th wheel as I did 9 years ago even at 25% SOC. I can not tell in my daily use. I don't worry about getting to a 100% charge either. This time of year it might be 2-3 weeks before they get a full charge (14.1v). 25-85 SOC range is normal in winter months of AZ, NV.

We don't live roughing it either. Couple laptops, phones, couple pots of coffee (10-12c) made. 900w microwave used through out the day, humidifier always going, 15k air conditioner for a couple hours of cool down if needed, tv ... just about as if plugged in. If the batteries need a little power boost I'll run the eu2200i generator for an hour or 2, the Magnum inverter/ charger will fill 20% capacity per hour or 100ah I don't run it more than 2 hours on occasion if the weather isn't agreeing for charging. 12-18 times in a year maybe the generator will get used for charging.