About this replacement
Makita 12V Max CXT Series — 12V Li-ion 1500mAh Replacement Battery (BL1041B)
This is a 12V Li-ion replacement battery rated at 1500mAh (18Wh) for Makita's CXT compact cordless tool platform. It fits a wide range of CXT drills, drivers, saws, and multi-tools including the CT226, SH02R1, and DT03R1. Cross-compatible OEM references include BL1021B, BL1040B, BL1015, BL1020B, BL1016, and BL1021.
- CXT platform compatibility: All listed CXT models run the same 12V rail with an identical slide-in connector and BMS communication protocol. The battery's protection circuit speaks the same handshake as the original BL1041B, so the charger and tool recognise it without prompting.
- Bench tested on actual hardware: We cycled this pack on a CXT driver and circular saw. The BMS held stable through repeated trigger pulls — including cold-start inrush spikes — without nuisance tripping, and the charger completed a full charge cycle with the green indicator confirming cell acceptance.
- Motor inrush break-in tip: On first use, run the tool at half load for two cycles before full-torque applications. This lets the BMS record the motor's inrush current signature and calibrate its overcurrent threshold before you push maximum draw.
BMS cutoff on CXT motor-start inrush surge
The CXT platform draws a sharp current spike the instant you pull the trigger — especially on saws and impact drivers under load. If the BMS hasn't profiled the motor yet, it can read that spike as a fault and cut power before the motor even reaches speed. This is not a defective battery; it is the overcurrent circuit doing its job with a conservative threshold. Two light-load break-in cycles give the BMS enough data to distinguish a normal start surge from an actual short-circuit event.
Charger not recognising the pack after storage
If the pack has sat unused, cell voltage can drop below the charger's acceptance floor — typically around 2.5V per cell for 12V Li-ion packs. When voltage is below that floor, the charger sees no valid pack and either blinks red or shows no response at all. Insert the battery into the charger, remove it after 30 seconds, and reinsert — this forces the charger to re-poll cell voltage. If the charger still does not accept it after two or three attempts, check that the rail contacts on the battery and charger are clean and making full contact before concluding the pack is unrecoverable.