subject: How To Tell If My Cordless Drill Battery Is Bad [print this page] Remove the battery from the drill if that battery must be removed to charge it. Place the battery into the charger and allow the battery to charge for three hours.
Unplug the battery charger from the outlet and remove the battery from the charger. Replace the battery to the power drill.
Pull the trigger on the power drill. If the power drill does not work after three hours of charging, then the battery is dead and needs to be replaced.
Cordless drills are powered by rechargeable batteries. Over time these batteries lose their ability to charge fully and maintain a charge. If your battery won't charge at all this is a simple way to get it to charge again.
If you are going to use the car battery charger be sure the two wires are not touching and plug it in. Touch the positive (red) to the positive (+) on the drill battery and touch the negative (black) to the negative (-) on the drill battery. Hold the charger on your battery for 5-10 seconds. This will give it enough of a boost to start charging again in your drill battery charger. If you don't have a car battery charger you can repeat the above steps using jumper cables from your car battery.
Touch the multimeter probes to the two battery terminals. Be sure to touch the negative probe to the negative terminal, and the positive probe to the positive terminal.
Check the voltage indicator on the multimeter. A fully charged battery should test at least 1 volt higher than the voltage that is listed on the battery. For example, an 18-volt battery should test at 19 volts or higher.
If the voltage indicator shows a high voltage, but the battery is still not holding a charge, it may need to be repaired. In that event, take the battery to a tool repair shop for more thorough testing and repair.
Unscrew the cordless drill battery case to open and reveal the battery cells to recondition. Take note of the inside spring so you don't lose it. This piece tends to snap out or pop away when the case is opened. Carefully lift off the top of the battery case.
Remove the terminal piece with needle nose pliers. Don't let the wires cross or touch during this removal. There is a risk of electrical shock or an explosion if you let the terminal wires cross. Set this piece aside with the screws and spring.
Set the volt meter to 2 volts and test each individual rechargeable battery cell. Mark all batteries with a volt meter reading of 0 or negative. This will denote which batteries within the pack need to be reconditioned.
Remove the clamps and test the battery to see whether it took the charge. If it reads more than 1 volt on the volt meter, move on and recondition the next cell. If the cell does not read more than 1 volt, zap it again. The cell can be zapped up to 10 times.
Using the volt meter, determine which leads on your battery case are positive and negative. Mark the positive lead, so that it is easier to reassemble your battery case after the reconditioning process.
Read the multimeter's voltage indicator. If it registers at at least one volt higher than the voltage listed on the battery, it indicates a fully charged battery that is able to take a full charge in a reasonable period of time. If the multimeter does not show a higher voltage, continue charging the battery.
