Lipo Charging Issues, please help!
 

Hey Guys,
I have 2 x IP 6000mah batteries and 2 x Energy 6500mah batteries. The IPs charge no problem at all, charging at 6amps they go right through the charge with no hassles and the charger tells me "charge done" (Much More Legend charger using the balancing cable).

The Energy batts charge at 6.5 amps fine (also using the balancing cable) for about 5000mah then the amperage drops slowly to about 0.3amps. I think its normal for the charge amperage to drop towards the end of the charge cycle but I'm not receiving the "charge done" signal from the charger and it eventually times out before the "charge done" signal comes on.

I have reset the charger and started charging the batts again but they almost immediately go back to 0.3amp charge and eventually time out again before the "charge done" signal comes up.

I have charged the batteries until they have approximately 6500mah in them and then discharged at 10amps and cycled through this process a few times. They seem to be holding about 6200-6300mah before the low voltage cuts in on discharge but when I got to charge them again the same problem persists. They just don't seem to "peak"?

Is this a common problem? Am I doing something wrong? Any suggestions on how to fix this welcome!

Cheers
Simon

What are the chances of the 6500 being out of balance. Are the 6500 2s2p configuration which tend to have balance issues.

The charger has auto balancing whilst charging and individual cell voltage read out. The cells seem to be within 0.1v of each other, not sure if this is acceptable?

That's acceptable, I never owned that brand so couldn't tell you that much but my 6500 2cell spc, I balance charge at 13amps and they reach capacity at 8.4v and somewhere around 8.35 I believe the amperage drops slowly to about .08 at the lowest, maybe try charging at 2c if your charger is capable and you might hit peak

After a few more cycles I think I've come to the conclusion that these so called '6500s' aren't :( they're more like 5500s I'd say. I think they aren't peaking because I've told the charger that they're 6500mah and they aren't getting to that.

Thanks for your help guys.

I dont normally tell people to do this, but set your charger to cycle and charge/discharge your lipos on a 4 circuit charge/discharge cycle and watch them as they bottom out to see what amps and ratings they pull. But make sure is a slow decline and make sure to keep a close eye on your temp. If by the 3rd discharge cycle they dont pull to the mAh rating then you probably got dooped one the rating. Were they used or new when you bought them??

I'll take the opposing view, 0.1V imbalance is quite a bit, I wouldn't consider that normal or acceptable. Surprised the charger can't pull them together after repeated tries. What are the cell voltages after discharging?

Yeah 0.1v is the max. More than 0.2-0.3v off I would discard it.

They do seem to be getting better now after repeated cycling. Charging to about 6400mah now and actually peaking properly. The balance is getting much better, within 0.03v of each other now.

They were bought new but I left them on the shelf without using them for a while. I thought they had decent storage charge in them but maybe they didn't?

Storage voltage shouldn't have had an effect on them like that.

They seem to be coming good anyway, maybe not full potential but peaking properly at least.

Thanks all for your help. :D