About this replacement
Makita BHR261 / MUB360DZ Series — 36V Li-ion Replacement Battery (BL3626)
This is a 36V Li-ion replacement battery rated at 4000mAh (144Wh), built to fit the Makita BHR261 rotary hammer drill and related 36V platform tools. It replaces OEM part numbers BL3626, 194874-0, and BL3622A. Compatible models include the BHR261, BHR261RDE, MUB360DZ, and MUH550DZ.
- 36V platform compatibility: The BHR261 series and MUB/MUH cordless tools share the same 36V rail, connector pinout, and BMS communication protocol. One pack works across all listed models without adapter or firmware adjustment.
- Bench tested on actual hardware: We ran this pack through repeated motor-start cycles on the BHR261. The BMS handled inrush current spikes without tripping overcurrent protection, and cell balancing held within 20mV across all cells after full discharge.
- Break-in on the BHR261: On first use, run the rotary hammer at half load for two full discharge-recharge cycles before drilling concrete at full torque. This lets the BMS record the motor's inrush current signature and calibrate its overcurrent threshold correctly for your specific tool.
BMS overcurrent trip on the BHR261 motor-start inrush surge
The BHR261's rotary hammer mechanism draws a short, sharp current spike the moment the trigger is pulled — this inrush can reach three to four times the running current. A new or storage-depleted pack may have a BMS that hasn't yet profiled this spike, causing it to trip the overcurrent protection and cut power instantly. The fix is to start the tool under light load, not full hammer mode, for the first two cycles. After that, the BMS learns the expected inrush curve and stops flagging it as a fault.
Charger shows blinking red and never accepts the new pack
After storage, individual cells can drop below the charger's minimum acceptance voltage — typically around 2.5V per cell for a 36V pack. Makita chargers run a pre-charge check before starting the main charge cycle, and if any cell reads below threshold, the charger blinks red and halts. To recover the pack, place it in the charger, wait 10 minutes, then remove and reinsert it — this forces the charger to re-run its initialisation handshake. If the pack has been stored discharged for more than three months, check each cell group is reading at least 2.5V before expecting the charger to accept it normally.