Several years ago I bought a Milwaukee compact driver. I use it mostly for driving screws. After a couple of years I was unable to get a full charge on each battery on the charger. The charger would operate for about a minute and then indicate that the battery was defective. The other day I put one of the batteries on my bench and measured the no load voltage, which turned out to be about 12 volts. I then connected a 220 ohm resistor across the terminals and about a day later, the voltage was down to 3 volts. I put the battery back in the charger and it charged normally to a full charge. I did the same to the second battery. The batteries are labelled as "Li-ion.
