Milwaukee makes a variety of battery-powered cordless tools. Battery packs and battery chargers are generally maintenance-free and operate for many years before going wrong. However, replacement battery packs often exceed a third of the price of a new power tool, so if you find your Milwaukee battery doesn't charge, check the charger first and then the battery before getting a replacement. It may be a simple fault that can be rectified.
Check the fuse on the Milwaukee battery charger, if it has a replaceable fuse. Some Milwaukee chargers have a fuse inside the sealed unit so you can't access it, but many have a fuse cover. If you can't access the fuse, go to step 3 to check if the charger produces an electrical output. Lift the cover from the charger unit using a small flathead screwdriver, or if it's held in place using a small Philips screw, remove the screw and then lift off the cover.
Pry the fuse from the fuse holder. Put a new fuse into the fuse holder; it must be the same type. If you don't have one, you can get a replacement from an electrical store. Replace the fuse cover. Simply push it into place using your fingers, or if it screws on, replace the screw and tighten using a screwdriver.
Read the label on the Milwaukee charger to find the output voltage it produces, if it's working correctly. Plug in your charger. Test it to check if it's producing a charge using a multimeter. The multimeter has a red and black wire extending from it and both wires have metal sensor on the end.
Place the sensor on the end of the black wire onto the outer metal pin plug on the end of the wire from the charger. Place the sensor on the end of the red wire onto the inner metal pin plug on the end of the wire from the charger.
Read the voltmeter display. It reads the same as on the charger label, if it's producing a charge. If it's producing a charge you know your charger is operating. If the multimeter display read on or near zero you need to get a replacement charger.
Plug in the charger to the Milwaukee battery, if it's producing a charge. Let the battery charge for about an hour. Unplug the charger and put the Milwaukee battery into the device it powers. Turn on the device. If it operates, you know it was the charger that was faulty, but if it doesn't operate, check the battery.
Check the fuse link in the Milwaukee battery pack. Remove the screws holding the battery cover in place using a Phillips screwdriver. Put the cover to one side.
Find the fuse inside the Milwaukee battery compartment. It usually near the metal terminal that plugs into the device it powers. It's a small plastic push-in clip about ½-inch long and very thin.
Lift the fuse from the holder using your fingers. Some fuses are clear plastic so you can see if the thin wire inside the fuse is broken, others you can't see through to you are unable to tell if the wire is broken. However, fuses are readily available from electrical stores and are inexpensive so it best to use a new fuse.
Put the replacement fuse into the fuse holder. Replace the battery cover and tighten the screws using a screwdriver.
Put your battery on charge. Leave it charging for about an hour. You may be able to tell if it's charging after half an hour as the battery starts to get warm. Turn off the charger and put the battery into the device it powers and turn it on. It operates, if your battery has taken a charge. If it still doesn't operate, get it checked out professionally, or purchase a replacement.