[Ziggythewiz]

Originally Posted by mizlplix

CALB is the only manufacturer with a cell in the 130AH range, to my knowledge. It fit my car and budget nicely.

That's good that you found a good fit. The fit for my imagined budget would be 80AH. 60 is borderline and 100 is really more than I need. Maybe the 40s I have now will incrementally grow into an 80AH pack that will last me until the nano-space megas are affordable.

[MN Driver]

Originally Posted by Ziggythewiz

That's good that you found a good fit. The fit for my imagined budget would be 80AH. 60 is borderline and 100 is really more than I need. Maybe the 40s I have now will incrementally grow into an 80AH pack that will last me until the nano-space megas are affordable.

The closest available thing would be to buddy up some 40Ah cells? ...or raise your voltage to get the capacity you need and you'd get increased performance. It looks like boosting your voltage would require you to swap out most of your electrical components though.

[Ziggythewiz]

Yes, the cells I have now will be for a lead/lithium hybrid experiment on parts of my pack, and if successful I'll likely expand it to be a full pack booster, then another string of 40 could be added to replace the lead entirely and give me the 80AH I need. Someday I'll upgrade to at least 144V, but my current setup would be more than adequate with some weight loss.

[mizlplix]

OK, just a P.S. to everything. Whilst putting my pack together, I found a really bulged cell.


It is one with .45 resistance.

To make matters worse, the bar code serial number ends withXXX0013

But, maybe it is really the best cell in the lot...Time will tell.

Miz

[onegreenev]

This is a REALLY bulged Cell from being driven into reversal with full pack amperage and a fully discharged cell. It actually still holds power but remains bulged. Capacity has not been tested.

[ruckus]

The Thundersky manual recommends that bulged cells be compressed in a giant clamp/vise thingy to bring it back to square before further use. I would be interested if such an operation could "save" this beastly looking cell.

[Tesseract]

Originally Posted by ruckus

The Thundersky manual recommends that bulged cells be compressed in a giant clamp/vise thingy to bring it back to square before further use. I would be interested if such an operation could "save" this beastly looking cell.

We tried compressing several bulged TS cells with a 20T bearing press.... After gradually increasing the pressure over a period of several hours for each one we got them back to looking normal, but they never did act normal again. The internal resistance remained elevated and the rate of self-discharge went from being practically non-existent to very noticeable. The cells bulge in the first place because the electrolyte has been dissociated into gaseous components (like passing current through water creates Hydrogen and oxygen) and those aren't ever going to reform into electrolyte again just by squeezing on the container!

Note that it is possible for the higher volatility solvents in the electrolyte solution to selectively "boil" which would also cause a cell to swell. If that is the culprit then putting the cell in the fridge for a few hours will reverse it; that won't work if the electrolyte has been dissociated from overcharging (above 4.3V) or reversal (below -0.4V).

[Ziggythewiz]

I think if there were anything to gain through compression, it would be in applying before swelling, or gradually after swelling and over a number of cycles.

The only way compression could be of an actual benefit (rather than the cosmetic band-aid many think it is) is if applying pressure changes the evaporation point such that the electrolyte stays electrolyte longer or reforms after damage has occured.

[ruckus]

I agree that a re-compressed cell will not be the same as it ever was.

My understanding was that air space was created around the cathodes during the swelling event. The re-compression pushes the electrolite back against it.

Obviously, you have tried it and it didn't work very well, which is to be expected with that kind of abuse. Even a cell that can be "half" recovered still must be pulled from a pack.

Has anybody tested whether the factory aluminum plates with banding is effective at preventing swelling under conditions that would normally cause damage? I would assume the cells would still be damaged whether compressed or not.

[onegreenev]

If you saw Jacks latest show you will know that banding or confinement will NOT prevent swelling. I have proof of that as well.