Batteries Battery Resurrection

Heliman450

Well-Known Member
Hi all, a friend from my flying club asked me if I could check out his 6S batteries for him as he's getting an error from his charger (he speaks German and instructions are English). I'm going to look for some German instructions for him, too.

So, the problem........

He's not been carrying out good battery care as we discussed elsewhere and both are very low down on volts and unbalanced. One is down to 13.31 V with two cells less than 2.0 V and the other is only showing 9.92 V with three cells not even showing anything at all. At the moment, they're out on the terrace in battery bags.

I guess it's time to tell him the bad news unless someone has an idea how they could be brought back from the dead.

Incidentally, I use the G.T. Power volt meter, which can read from 2 to 6S batteries as well as balancing and discharging. When I bought it about two years ago all my 3S batteries were out of balance despite using a balance charger. After using it to balance them, they subsequently remained balanced without repeating the exercise.

Bye now!
 

Smoggie

Well-Known Member
The one registering zero volts is toast if it's been that way for a while.

The one with 2V per cell might be recoverable as long as there is no puffing (if it's puffed ditch it). The way to recover an over discharged lipo is to set the charger to NiCd/NiMh battery type and charge at very low current (about 0.5C). If you have a balance lead voltage checker plug it into the balance lead and watch carefully as the cell voltages increases. when the cells are all up to about a minimum of 3.3V stop the charge. Don't let any cell go over 4.2V. If you dont have a cell voltage checker manually check each cell with a multimeter.

Assuming all the cells came up to voltage ok now put the charger back to LiPo setting and balance charge as per normal.

It's really important that you monitor the battery very closely at all times in this process, and don't whatever you do leave it unattended when on NiCad setting, and NEVER allow any cell to exceed 4.2V. Treat the battery with caution for a few cycles afterwards until it shows consistent normal operation.


Some people will of course tell you to just throw the batteries away, that's your call at the end of the day. I've previously recovered a few over discharged batteries and they went on to work normally for years, so it can work, but it's hit or miss.
 
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Heliman450

Well-Known Member
Hi Steve, thanks for the prompt feedback on this and the tip for rescuing batteries.

I think I'll just tell him the bad news and not try to do any more with them as on one battery there are three of the six cells not registering anything at all (not even a display for them!). The other battery has two cells from six below 2 V.

Cheers!
 

murankar

Staff member
Just keep in mind that the packs you are going to recover are now damaged. Are they still usable? Yes but they are still considered damaged. Due to the over discharging of the packs they now have higher internal resistance. Anyhow Steve basically covered it all.
 

Heliman450

Well-Known Member
Hi Matthias, thanks for the extra info. I've already decided not to try to revive them particularly as they aren't my batteries and I don't know what's happened to them.

The chap has a real mess with his three helis and I suspect he's just left them until someone like me came around to help him out of it.
 

Smoggie

Well-Known Member
FWIW on some of the batteries I recovered there was no detectable damage. Their IR measured similar to others from the same batch and they performed the same as far as I could tell. Some of these batteries are now 5 years old and all but one from the batch are still serviceable though they have spent most of the last few years in the fridge. Funnily enough last week one failed due to a cell puffing, I'm unsure if that was one of the ones that had been over discharged or not.
 

Heliman450

Well-Known Member
FWIW on some of the batteries I recovered there was no detectable damage. Their IR measured similar to others from the same batch and they performed the same as far as I could tell. Some of these batteries are now 5 years old and all but one from the batch are still serviceable though they have spent most of the last few years in the fridge. Funnily enough last week one failed due to a cell puffing, I'm unsure if that was one of the ones that had been over discharged or not.

Hi Steve, in the context of the thread your feedback is invaluable. I've picked up lots of areas where my own battery management has been lacking and it's great for others to look in and share the exchanges. For example, my drinks cooler at the workshop gave up and I'm intending to discuss with my good lady replacing it with a fridge to enable me to store batteries as was suggested in another thread.

Regarding my current challenge, the guy who owns the batteries also owns the heli field (it's his farm in the video) so for me he's top VIP in the area!!! Up to now, I've only given him bad news from my investigations. If he wants to continue with the hobby, he'll have to lift his game on many fronts but I'm going softly, softly right now. We'll see................
 
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