How low are we talking here?

Chances are your pack is fine. Its only a placebo effect that you're feeling with your packs loosing steam since you and your son know the pack you are using were the one you "over discharged". Ive had this happen to me a number of times where I thought the packs I put in the car was charged, but ended up hitting voltage cutoff. My packs still runs fine, didnt puff up or anything and been running strong for almost 2 years.