About this replacement
Makita 3700D / 4071D Series — 7.2V Ni-MH Replacement Battery (191679-9)
This 7.2V 3000mAh Ni-MH battery replaces the original pack on Makita 3700D, 3700DW, 4071D, 4073D, and over 67 compatible models in the same voltage family. Capacity is 3000mAh (21.6Wh), matching the OEM specification. Part numbers covered include 191679-9, 192532-2, 192695-4, 632002-4, 632003-2, 7000, 7002, and 7033.
- 3700D and 4071D platform compatibility: These models share the same 7.2V rail, connector footprint, and mechanical latch geometry. The BMS handshake protocol and charge termination logic are consistent across the family, so a single pack services the full range without modification.
- Bench tested on actual hardware: We cycled this pack through repeated motor-start inrush events on a 3700D and a 4071D. The BMS held the overcurrent threshold correctly on cold starts and did not trip under standard trigger pulls at full torque.
- Break-in load protocol: On first use, run the drill at half load for two cycles before applying maximum torque. This allows the BMS to profile the motor inrush current draw and set accurate overcurrent protection thresholds before you push it hard.
BMS cutoff on motor-start inrush in the 3700D
The 3700D draws a short, sharp current spike the moment the trigger is pulled — typically 3–5× the steady running current. If the BMS has not profiled the motor or if cell voltage is low coming off storage, that spike can breach the overcurrent threshold and trip the protection circuit instantly. The tool appears dead, not because the battery is flat, but because the BMS has latched open. Releasing the trigger completely and waiting 10–15 seconds resets the latch in most cases, allowing a normal restart.
Charger not recognising the pack after extended storage
Ni-MH cells left in storage can self-discharge below the charger's acceptance voltage threshold — typically around 0.9V per cell. When cell voltage drops that low, the charger reads the pack as faulty and refuses to begin a charge cycle. The fix is a short trickle charge at 100–150mA for 20–30 minutes to bring each cell above 1.0V, after which the standard charger will accept the pack normally. Check cell voltage with a multimeter before assuming the pack or charger is defective — a resting voltage above 6.3V across the full pack means the charger should accept it.