Last night I gave this a try on a 14.4V that has been dead for about 2 yrs. I measured it w/meter and it shower .0 V then quickly jumped it w/ a good 19.2 several times and it showed 8v. I put it in the charger and it still wouldn't do anything...even show as defective. I put the jumpers back on it and touched it to a huge 950 amp 12V battery I have hoping to "shock" it a couple of times and it showed about 12V after that but still wouldn't work in the Craftsman quick charger. I then connected the jumpers to my 12V automotive battery charger @ 10 amps and left it for about 2 hrs......miraculously when I checked it it showed over 14V and spun the drill like there was no tomorrow ( don't know how a 12V charger can bring it to 14+V, but it did. I put it back in the Craftsman charger and it still doesn't register default,charge or full charge but it is working again. I'll just use the jumpers/auto charger from now on and see what happens but for now it's working again.