Admitting to collossal mistake - LifePo4s way overcharged

[Famtraveler24]

Folks. Don't leave your charger unattended. Left mine on overnight and woke to find my 1s8p cells I was trying to top balance at 4.7v.

They are way swollen and I'm considering them DOA.

Lesson learned.

 

[littleharbor2]

Folks. Don't leave your charger unattended. Left mine on overnight and woke to find my 1s8p cells I was trying to top balance at 4.7v.

They are way swollen and I'm considering them DOA.

Lesson learned.

I did the same thing with my first "starter set". What a sick feeling seeing them that morning. Once I set the voltage on the power supply to 3.65 I must've inadvertently nudged the voltage adjustment knob while covering and uncovering the battery pack daily.

 

[upnorthandpersonal]

Folks. Don't leave your charger unattended. Left mine on overnight and woke to find my 1s8p cells I was trying to top balance at 4.7v.

They are way swollen and I'm considering them DOA.

Lesson learned.

PSA: Whatever you do, set the voltage on the supply to 3.6V and then connect to the cells. Don't touch the power supply after that. The voltage goes down, that's normal. If your current isn't maxed out, you have bad connections.

Something I wrote some time ago:

DIY Battery Handbook

With the increasing amount of users on the DIY Solar Forum and more people exploring the options to build their own battery packs we've seen common mistakes and dangerous situations occur more frequently - sometimes with disastrous outcomes. While many of the issues we come across have been...

diysolarforum.com

 

[Famtraveler24]

I stupidly got a power supply that wouldn't let me set voltage appropriately in an effort to charge with higher current. Live and learn

 

[Steve_S]

Folks. Don't leave your charger unattended. Left mine on overnight and woke to find my 1s8p cells I was trying to top balance at 4.7v.

They are way swollen and I'm considering them DOA.

Lesson learned.

ouch but not necessarily DEAD but certainly suspect until tested..

Now the NASTY ! sorry but it is what it is...
1) You need to examine the cells to verify that NONE popped their valves and that none are leaking in any way. IF they are leaking then the cell is dead ! Dispose of according to local rules & regs... Lithium Recycling is taking off very fast, so should not be hard.
2) IF all cells are intact and "clear" then follow these steps below:
- Get them down to at least 3.650Vpc and allow a good time to settle... Nerve wracking patience test...
- Then discharge the pack "Moderately" as in No Higher than 0.5C down to JUST below 3.000Vpc and again allow them to settle a few hours without charge./discharge (disconnected better)
3) IF pack was disassembled you can VERY GENTLY squeeze the cells by HAND and you will note that there is a bit of Give and you may hear a slushing sound if you shake the cell a bit, THAT IS GOOD ! IF there is No Give and no Slushing sound, that's not so good.
4) If GOOD, then you can gently squeeze the cells with FLAT BOARDS covering the faces, squeeze them GENTLY by hand (Quick Grip lamps are great for this BTW) then let sit an hour, give them another "little squeeze" and you'd be surprised that 2-3 times squeezed "Lightly" will square them up fairly well. * IF you squeeze too much or too hard and CAN pop the cell making it junk.. LIGHT TOUCH REQUIRED !
5) Once flattened/squared bind the cells and parallel charge then to 3.600Vpc and observe carefully to make sure they are still sealed & dry.
6) If they pass above then you can reassemble pack and resume use.

You may have lost a little capacity and if they have not popped the vents or leaked are likely still OK. They can take a "Little" abuse but not very often as they are most persnickety to say the least.

WARNING !
IF the Electrolyte has leaked, Wear Rubber Gloves and BE CAUTIOUS, if you get any on you wash it off IMMEDIATELY !

About Clamping / Binding. I will not get dragged back into that circular of arguments & nonsense. 10-12PSI MAX is all that is needed, that is a "Good hand squeeze" tight (not a forceful crush people) and this should be done WHEN THE CELLS ARE AT 25C/77F temp and at 3.200 Volts per cell ! Personally over the years I learned to bind the cells into 4 Cell Block Modules because it is a LOT easier to do and when it comes to maintenance etc, it's easier to work on modules rather than pulling 8 or 16 cells out at once (What a freakin PITA that is).

QuickGrip Clamps I mentioned which I use for Many things below.

Parallel Bar Clamps | IRWIN

www.irwin.com

Hope it helps, Good Luck.

 

[Famtraveler24]

Thx for the helpful info. None of the valves are popped. Just swollen pretty good and I see no evidence of leaking. I'll give it a shot. Wish me luck!

 

[Steve_S]

My Best Wishes & Thoughts are with you my friend. Even crossed Fingers added in for extra good luck.

 

[NorthTown2022]

Thx for the helpful info. None of the valves are popped. Just swollen pretty good and I see no evidence of leaking. I'll give it a shot. Wish me luck!

Were you able to save them?

 

[RCinFLA]

They may not be useless but will have suffered some degradation. Must not have overpressure port burst though.

Above 4.3v electrolyte decomposition accelerates greatly.

Electrolyte decomposition creates the outgassing bloat. It is not the bloat that is the major damage. When electrolyte breaks down it creates tar-like by-products that clog up electrode anode and cathode pores. This adds ion diffusion resistance to lithium-ion movement through cell increasing cell impedance which means you get more cell terminal voltage slump at moderate to high cell current.

 

[Famtraveler24]

Were you able to save them?

No. They are DOA

 

[FoxMeister88]

That sucks. I initially learned from someone here in the forum when doing top balance to just do the bulk charge with the BMS first (16S in my case), then top balance with a good variable power supply (16P) set at 3.6v and monitor the voltage before plugging the battery in and every hour or so during the process. But then I went ahead and stripped like 6 terminals right after top balancing... Can't escape my own stupidity lol.

 

[WYtreasure]

I am still trying to figure out why folks use a power supply when they already have a charge controller.
I understand not all charge controllers charge at all voltages but for those who can use a controller and balancer(s), why not?

Could this method work if cells are connected to match controller voltage?

 

[DerpsyDoodler]

I am still trying to figure out why folks use a power supply when they already have a charge controller.
I understand not all charge controllers charge at all voltages but for those who can use a controller and balancer(s), why not?

If you're parallel charging 3.65v cells you need to supply 3.65VDC. Most charge controllers are either 12V, 24V, or 48V.

Could this method work if cells are connected to match controller voltage?

That would be series charging and yes, but you better use a BMS to monitor and stop charging once a cell hits 3.65V.

 

[WYtreasure]

If you're parallel charging 3.65v cells you need to supply 3.65VDC. Most charge controllers are either 12V, 24V, or 48V.

Yep, parallel would not work.

That would be series charging and yes, but you better use a BMS to monitor and stop charging once a cell hits 3.65V.

So the charge controller & balancer(s) won't address that issue?

 

[DerpsyDoodler]

Yep, parallel would not work.

So the charge controller & balancer(s) won't address that issue?

As long as the balancer can keep up with the charging current, sure. I would still rather have my investment protected with a BMS though.