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ClearwaterMexico

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Aug 23, 2021
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I just connected a regulated power supply to 4 new 280 ah cells (connected in parallel) and REVERESED the negative and positive.

Within a few seconds, there was a pop, followed by the distinct smell of electronics burning.....no fire, just that SMELL!

The cells will NOT accept a charge and are stuck at 3.3 volts

Is there anything I can do except throw away $423.00?
 
SOrry.....i wasn't clear.

Yes the POP was the power supply, the power supply's output went to ZERO.
I got a new power supply and hooked it up (correctly) to the cells.
It ran for 4 days and the battery voltage never got higher than the original cell voltage of 3.3 vdc.
I do not think it could be the power supply.

AND the cells have expanded and swelled.

Can they be recovered????
 
Dear @ClearwaterMexico

Welcome to the forum and sorry that you’re experiencing unpleasant battery time.

How much did the cells swell?

If you are comfortable sharing an image of the affected area, it might help diagnosing what’s going on.

If they look like balloon then definitely not safe to use anymore and no method to fix cell after swell.

Again, sorry to hear you’re experiencing these trouble.
 
A few comments and questions I'd like to inquire about op's situation, and get everyone's opinion:
1. $425 for 4 new 280Ah cells? That's a good price!
2. Would a few seconds of a benchtop ps attached in reverse really kill 4 new 280Ah cells? I'm guessing you set it to 3.6+/- V and how many Amps? Even most low end ps have reverse polarity protection. Clearly, yours didn't, or it failed.
3. My cells swell a bit once on the high end state of charge, so op's observation of "swelling" is subjective. A pic would be nice.
4. This second ps you've had attached for 4 days, was this a 24/7 for 4 days thing? How many amps did you have it set to?
If the answer to #2 is a solid yes AND #4 is a yes, then I'd say those cells are no longer reliable. I'd just hate to have to trash 4 new cells without being sure.
 
In a second, a power supply applied to lithium cells probably wouldn't damage them. The cells would damage the supply if backwards.
I think resistance through incorrectly biased transistors and capacitors would be high enough the cells wouldn't see a direct short, rather would deliver a tolerable couple hundred amps at most.

New supply connected correctly, if it charged cells higher than 3.6V and stayed for days, that would cause damage.
If only applying 3.3V indefinitely, shouldn't be any damage. Still 3.3V would indicate hasn't hit knee of curve.
"Swelled" - as has been asked, swelled how much? Some swelling reportedly occurs during charging.
People often clamp to prevent slight welling, because vendors indicate that extends life.

How much current was flowing during charging?
What voltage was supply set to?
 
For a battery to fry that quick seems off to be honest.....

But I'm used to dealing with lead acid for the most part.

Can you test your charger?
 
In a second, a power supply applied to lithium cells probably wouldn't damage them. The cells would damage the supply if backwards.
I think resistance through incorrectly biased transistors and capacitors would be high enough the cells wouldn't see a direct short, rather would deliver a tolerable couple hundred amps at most.

New supply connected correctly, if it charged cells higher than 3.6V and stayed for days, that would cause damage.
If only applying 3.3V indefinitely, shouldn't be any damage. Still 3.3V would indicate hasn't hit knee of curve.
"Swelled" - as has been asked, swelled how much? Some swelling reportedly occurs during charging.
People often clamp to prevent slight welling, because vendors indicate that extends life.

How much current was flowing during charging?
What voltage was supply set to?
These are the questions I'm curious about. A few seconds of reversed wiring, and poof!! A fried the ps..I get that. And a new ps is attached (unknown settings) and no measurable progress after 4 days? Is that 96 hrs continuous? Lots of unknowns here. I guess I just wondered if cells can be unrecoverable after such a brief reversed polarity situation, like what op has presented.
 
We need more info, I hope OP feels comfortable to discuss it more.

We all do oops. Picking up what’s leftover and moving forward is what it’s all about ☮️
 
We need more info, I hope OP feels comfortable to discuss it more.

We all do oops. Picking up what’s leftover and moving forward is what it’s all about ☮️
Agreed. Personally, I learn much more from a failure. I'm constantly testing and experimenting w various settings, setups..etc.. I'm a "I wonder what would happen if I..." kinda guy..lol..
 
Just tell us st what current you are charging. All Batteries in parallel?
 
I did the same thing, and my PSU popped a capacitor. Replacement was actually pretty easy, I could clearly see which one had blown.

It can take weeks to top balance multiple 280ah cells in parallel. You may not have had them charging long enough to see a voltage difference. My cells went up about .2v over a week, then shot up from around 3.35v to 3.6v in a few hours. The discharge / voltage curve on LiFePO4 is almost flat, which means that voltage has very little to do with state of charge.

Also, make sure that you set the voltage on the PSU BEFORE you connect the batteries.
 
So you're charging at 1.5A, 0.005C
Should only take about 8 days (if starting from empty)


Do you have a BMS yet?
 
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