Well, I built these from DeWalt packs, so I could have messed them up a little in the assembly process......but I do think this particular cell was defective or something.

Before charging, I discharged with my Deans 20a light bulb discharger and then set it to charge at Nimh 4a on my Pro Peak Prodigy 2........I don't remember how much it took, but the charger began to beep that the pack was peaked, and I heard the infamous pop.