I had a few packs I did this too and worked awesome. If you have a pack that won't charge or shows real low voltage when charging, one of the cells is at 0 volts. Find the dead cell and take a charged pack of batteries and tough the positive of the charged pack to the positive of the dead cell, and same for negative. It will shoot some voltage back in the dead cell and bring it back to life. I have had 4 packs now I have done this too and it works. 1 pack has been sitting in my garage for months and I did it tonight and BAM it is back and one of my best.... good luck!