I use two 3s 4000mAh batteries on my E-Revo Brushless and I didn't disconnect them from the Revo when I stop using it. After a month or so I try to charge them but the charger show me this error "Low voltage".
So I tested with a voltimeter and I had in one cell 2,5v in the other 2v and 0,3v In The last one. I tried charging them with the traxxas lipo charger at 800mAh and two of the cells charge up to 4,2v but the third is still in 0,6v.
I have a Hi-Tec charger and after charging them with the traxxas I put it with this one and it only detects two cell.

If anyone knows what should I do please help me!!