This is a brand new $30 4S LiPo fresh out of the packet, never used (click to enlarge)...

 

The supplier is issuing me with a refund but has told me not to bother sending it back. It's currently back in the ammo box along with all the others.

I know what the sensible thing to do is. However it seems a bit of a waste to just bin it when it has 3 brand new perfectly good cells, but I'm fully aware of the dangers of these things. So the big questions are:-

1. Do I completely discharge it (not sure how exactly with it having a "bad" cell) and just dispose of it at a battery recycling facility.
   
2. Do I cut off the shrink wrap and tape, and see if it can be repaired (maybe the balance connector wire for cell 2 just hasn't been soldered onto it properly).
   
3. Do I try to make a 3S out of the 3 good cells (assuming cell 2 is actually bad and beyond salvaging).
   

If I try either 2 or 3 it would be outside well away from anything flamable with a fire extinguisher next to me.

I would just remove the bad cell. I have two 3S packs that started life as 4S. As long as you do not short anything in the removal process, you will be fine.

I would open it up and look for the problem as its easy to re-heat shrink or tape it up. If it's a bad cell then do like Kaity said and turn it into a 3s pack.

I agree with Sugs and Kaity.....mostly because you're so anal it will be done correctly....most others I wouldn't recommend it!  As the recent memes are saying, Just Do It!! Besides, a house that doesn't smell like smoke is just silly....

OK, you've all convinced me to take the "dangerous" option 

Of course, you know full well it will probably take me 6 months to actually complete this, so I'll report back in Spring 2019 with the results 

https://oscarliang.com/fix-lipos-bad-cell/#more-11910

As said, it's pretty simple to do. But the question is , will you ever use a 3S?. No use taking the 1 in a million chance that you'll burn your house down for a battery that'll sit on your bench for 2 years then tossed.

(17-Sep-2018, 01:38 PM)RENOV8R Wrote: As said, it's pretty simple to do.  But the question is , will you ever use a 3S?.  No use taking the 1 in a million chance that you'll burn your house down for a battery that'll sit on your bench for 2 years then tossed.

I thought 3S was the way forward, no?  Or was that 6S? I was never any good at maths   

If it can't be revived as a 4S (i.e. if the problem is just a broken balance lead wire) then a 3S battery could prove handy for use with a smoke stopper because it can be difficult to use a 4S battery for that without risk of blowing the 12v bulb unless it's pretty much depleted to its lowest safe minimum voltage.

I've still not decided what to do but until I get issued with a refund (which hasn't happened yet), I won't be doing anything with it.

If you're taking it apart anyway then a 2S might be useful as a spare goggle battery.