Makita Battery Fixed in 10 Minutes With a 20-Cent Part Instead of E-Waste

Power tool battery packs are rarely designed for user servicing, so a dead pack outside warranty usually ends up in the trash. The Repair Forge channel took a different route: the author opened a faulty Makita pack, diagnosed the issue, and restored it in just a few minutes.

The charger did not throw an error but never started charging: the red LED blinked, the fan spun, and the battery stayed empty. That behavior suggested the charger believed the pack was either too hot or too cold to charge.

Using the open-source PocketOBI tool, the battery could be queried. One internal thermistor reported −30°C, while the other showed a sensible 28°C. After cracking open the case and measuring resistance, the faulty thermistor read infinite resistance, confirming it had failed.

A temporary resistor verified the diagnosis, and the battery came back to life. Replacing the thermistor itself was the final step — the part costs about 20 cents. The same procedure fixed a second pack, where the thermistor reported 64°C.

The whole process from diagnosis to repair takes roughly ten minutes with PocketOBI. That tool builds on the Open Battery Information project, which originally reverse-engineered the Makita battery protocol.