Whether you own a Makita drill, saw or other cordless power tool, all nickel metal hydride Makita battery packs can be repaired. Within each Makita rechargeable battery pack, a number of smaller rechargeable batteries are linked together to obtain the proper voltage level. If even one of these batteries goes bad, the entire chain will not work and neither will your tool. The Makita battery packs can be repaired with just a few simple tools.
Open the Makita battery pack with a screwdriver and locate the chain of nickel metal Hydride (Ni-mh) batteries to be repaired. Pull these cells out of the Makita battery casing.
Determine how the cells are placed in line. Using a pencil and paper, jot down the polarity of the line of batteries. Note the pattern and how the cells fit into the casing for easier reassembly.
Test each individual Makita Ni-mh battery cell in the battery tester to determine which ones are bad. Mark the bad cells that will need replaced.
Purchase the same sized Ni-mh replacement batteries. Only replace Ni-mh batteries with Ni-mh batteries. The type of batteries must remain the same throughout the battery chain.
De-solder the first "bad" Makita Ni-mh battery cell from the chain. Re-solder in the new Ni-mh battery.
Repeat this process with the entire Makita Ni-mh battery chain until completely restored. Replace the chain within the Makita battery case.
Place the cordless tool on the charger overnight and it should be as good as new.