blueberry

I was in a hurry yesterday but I thought I would get a quick flight in on my foamie.
When I was done I just put it up on my bench and I forgot to disconnect my battery pack.
It is a Thunderpower 3 cell 1320mah it now reads 2 volts and my Apache charger will not charge it. Is there anything I can do or is it JUNK?

Thanks,
Pete

Fletch124

My Feedback: (7)

I have done something to one of my li-po's that made it do the same thing. I called up Horizon and they said it was Junk!

thedak

My Feedback: (21)

52 bucks down the crapper

Mike Glass

You may be able to save the pack, but your going to need a charger that can trickle charge Li-pos.
What happens is when the voltage is too low in the pack the charger can't read the cell count and if your charger dosen't read the pack and just charges at the rate you selected the pack will swell and be garbage.
When the voltage is too low the pack can't take the normal rate of charge and the voltage will rise rapidly and swell the pack!

How do I know this? Well it cost me 3 packs to discover this! At the time when the lipos just came out I bought one of the only chargers on the market. The small gray Kokam charger. As you may know this charger only know what you tell it and dosen't monitor the pack at all. The early pack had very small C ratings and couldn't hold up to the beating I was giving them and the pack voltage would drop very low. I'd hook them up to the charger and it would swell the pack and the batteries were garbage. After talking to Astro Bob he explained to me what was going on!

Now I've been through this before so now I'm care to read the pack voltage as soon as plug in the pack. I plug the pack into my Astroflight 109 charger and the voltage was down to 3.5 for the pack a 3 cell 830.
Well the pack hasn't been charged since maybe Oct. and I was setting up a plane with it for the last few nights and it had enough power to work the servos, but not the motor till the point when it went totally die!

My Astro 109 was reading the pack as a 2 cell pack as well. What I did was to set the charger at .010 rate. the voltage started to rise very slowly. I watched the pack and the charger till the point at which the voltage was up to around 11 v. I unpluged the pack and reset the charger. Pluged the pack back into the charger and it read it as a 3 cell pack and I charged the pack at the normal rate and it was fine. I,ve charged the 5 or 6 time since and have had no problems with it at all. Bob was right!

I hope this helps?

Mike

blueberry

Thaks for the quick replies everybody.

Mike
I will see if I can find someone with a charger capable of that and give it a try. I will however monitor it very closely.

Thanks,
Pete

tylerman

Change the cell count to 2 cell and charge it to lower mAH. setting and it will be fine.

blueberry

tylerman

I tried that and it still would not work. I will try it with a different charger if I can find one.

Pete

thedak

My Feedback: (21)

throw it away before you burn your ball bag off.

Ian.W

Ive discharged my kokam 340s (3s) down to 1v per cell. My charger just charged them up veeery slowly (like .1A) to 9v per cell then started charging away normally. It took a few cycles to get back to performance but as its happened twice now, and the packs still going....

i suggest you try a different charger, i use a pro-peack prodigy, i think its a jamara charger with a different front plate. basically try all your mates chargers, if nothing works, youve killed it

Ian

Mike Glass

Burn your ball bag off ? Thats got to leave a mark!


Mike

blueberry

Ian
I'll give it a try. what do I have to lose besides my bag.

Pete

tylerman

Go get a Triton charger. It will be the last charger you will ever need to buy.

blueberry

tylerman,

Is the Triton capable of recharging a battery like this.

Pete

locoworks

JUNK it, even if you risk a recharge as described earlier in this thread ( i'm sceptical about being able to do that ) there is no way the cells will be anywhere near balanced, one of the end cells ( can't remember positive or negative ) will be lower than the others.

bdavison

My Feedback: (1)

Im a little skeptical about being able to recharge it too, and even if you do manage to get the voltage back up, there has already been damage done to the battery which could cause who knows what to happen. The reason lipo's go dead when the voltage drops below 3V per cell is because that is the point at which the polymer loses its ability to maintain a charged state.
Since our lipo's aren't true li-poly...(they still have lithium-ion electrolytes mixed in), its possible that the "recharges" these guys have experienced are just charges of the electrolyte not the polymer itself.

Also just because the voltage comes back up, doesnt mean the battery is good. You may have one low voltage "dead" cell and one overcharged cell. Which is even more hazardous.

Also trying to recharge a battery that has gone below its MINIMUM required voltage is hazardous. The battery could swell up and explode at anytime if the cells are mismatched and a cell is getting overcharged.

I would recommend chunking it. Its alot of risk, and even if you can get it charged up, there's no telling when its going to kick the bucket.

If your determined to try it, I would recommend disassembling the battery pack and charging each cell individually. Then and only then will you know if you have one bad cell, and you can prevent overcharging the other remaining good cells. If you dont have experience disassembling or assembling lipo packs, DONT attempt this.

Soldering tabs on lipos is very difficult and potentially hazardous. You have to solder nickel and silver, and overheating can cause the lipo to get too hot and burst.

Ian.W

Not quite true, i just resoldered tabs on my lipos the other day, i used aluminium solder on the tabs, then normal solder over that then thats fine. The cells didnt even get warm

TedShredz

I did the same thing with two of my 3c packs in parallel. I lost one 3c pack. I tried all the tricks using my Triton and nothing worked for the worst of the two....but testing showed that one of the 3 cells was gone

If I seperate the bad cell, I might get a good 2 cell, but after the hardship of low voltage, I might not get good performance....something I have to expect for being careless...

Oh well........

Ted

blueberry

Thanks for all the input everyone.

Pete