How to Repair a Panasonic EY9021 Power Tool Battery

Whether you own a Panasonic cordless drill, saw or other cordless power tools, all nickel metal hydride (Ni-MH) Makita power tool battery packs can be repaired. Within each Panasonic EY503B cordless drill 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 power tool. The Panasonic drill battery packs can be repaired with just simple tools.

Repair Ni-Mh Panasonic EY9021 Cordless Drill Battery Instructions

Open the Panasonic power tool 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 Panasonic drill battery casing.

Determine how the battery cells are placed in line. Using a pencil and paper, jot down the polarity of the line of batteries. Please note the pattern and how the cells fit into the casing for easier reassembly.

Test each individual Panasonic Ni-mh drill battery cell in the battery tester to determine which ones are bad. Mark the bad battery cells that will need replaced by brand new battery cells.

Purchase some the same sized Ni-mh replacement batteries. Only replace Ni-mh bateries with Ni-mh batteries. The type of batteries must remain the same throughout the Panasonic power tool battery chain.

De-solder the first “bad” Panasonic Ni-mh battery cell from the chain. Re-solder in the new Ni-mh battery for Panasonic cordless drill.

Repeat this process with the entire Panasonic Ni-mh Panasonic EY9106B power tool battery chain until completely restored. Replace the chain within the Panasonic tool  battery case.

Place the cordless tool on the drill battery charger overnight and it should be as good as new.