Cordless Rotary Hammer Drill Restoration and Battery Rebuild 7S60A

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This tool is obsolete because it runs on old Nimh batteries. It was abandoned in Japan. Everything is fine except for the battery and the charger. I bought it to restore and want to know its quality.

All that needs to be done is to clean the internal parts, put in new grease, and especially make a new battery with lithium that has the same power as the old one. The original battery contains 20 of Nimh batteries. Watch the video from Gear Show:

The Nimh battery cell fully charged voltage is around 1.5V so with 20 cells in series connection, the total voltage is around 1.5V x 20 ~ 30V.

The lithium battery 18650 cell fully charged is 4.2V, so to get voltage around 30V I need connect them in series 7 times. 4.2V x 7 ~ 29.4V. I choose bms 7S60A high load current from battery pack to the motor. After restoring and trying to use it, I am very satisfied with this result.