Lipo Charging Via Outback Solar

[spdas]

Aloha, All. I WAS doing great charging my 16s 5000mah pack. I am using solar panels going through an outback charge controller. I was getting very accurate and safe charges. (50 charges and 400 miles to date)---UNTIL last night. I decided to put the batteries on charge, even though there was no sun and no amps, I thought at the first light in the morning, my pack will be charging. BAD IDEA. The charge controller sucked my batteries DEAD. I am trying to revive them (although i have little hope...but maybe??) All the cells are at 1.6V or so with one a .06 volts (dead dead).

Any experience from you trying to revive the cells? (they are not bloated) and now I have 8s charging at 2.2 constant currant @ 13.2V, and voltage seems to be rising slowly, but maybe not as I have had 2.5 amps Constant current for 2 hours and voltage is still at 13.6V.

thoughts?

francis

 

[RageNR]

Ooohh, not good. Gotta be mindful of the drain from solar without sun.
I am not that knowledgeable with the lipo charging yet. Learning as fast as I can. What I do know is you need to recover them ASAP. The less time spent at lower voltages, the less damage will occur.
What I think you need to do is get a small amount of voltage to that dead cell right away. I would start with 1-1.5v till it comes up. Monitor it for heat.
I would not put it on a charge controller yet until you have the voltages close to another again. Try to manually charge them through the balance lead. Use low voltage/low amperage until you can get it to come up.
If it starts getting hot, stop. Work your way up and get them into the 3v range, then you would probably be safe to but them on the charger again.
BUT MONITOR THEM CLOSELY!! Can't stress that enough. Good idea to do this outside.


Hopefully someone more knowledgeable than me will jump in here in a bit. My suggestion above should be safe with a close eye. Good luck.

 

[spdas]

Well, 15 of the 16 cells charged up. (not sure if the wattage will be effected though.) The 16th and dead cell was a black neg. on the outside, so fairly easy to change.

BUT--

Had some problem with soldering. The tabs seem to be Stainless-Steel and seemed to be put together by machine crimping.
I had a hot gun 100-140 Watt, but had a hard time getting solder to stick. I used thin rosen core solder. Is there a method to solder-unsolder?

thanks
francis

 

[amberwolf]

Depending on the rate they were discharged at, if that's RC LiPo, they could be a fireball waiting to happen after being drained down so low. Unfortunatley you won't know till it's too late.


As for soldering...if youve been heating up the cell(s) with the iron for more than a second or two then the heat can seriously damage them too. (some could be damaged even in that time).

I highly recommend reading around on the various pack-building threads, including the ones about soldering on cells, for methods that may work and methods that don't and why.