About this replacement
Makita 12V Max CXT — 12V Li-ion 5000mAh Replacement Battery (BL1041B)
This is a 12V Li-ion battery at 5000mAh (60Wh) capacity, built to fit the Makita 12V Max CXT platform. It covers a wide range of compact cordless tools including drills, impact drivers, and circular saws across the CT226, SH02R1, DT03R1, and 76+ additional models. The BL1041B OEM part number is the primary reference — cross-compatible with BL1021B, BL1040B, BL1015, BL1020B, and related variants.
- 12V Max CXT platform fit: All listed CXT models share the same 12V rail, physical slot geometry, and BMS handshake protocol. The connector pinout and latch mechanism are uniform across this series, so one battery services the full tool lineup without adapter hardware.
- Bench tested on actual hardware: We ran this pack on a CXT drill and impact driver. The BMS handled repeated trigger-pull inrush cycles without nuisance tripping, and cell voltage balanced correctly across the charge-discharge curve under both light and sustained loads.
- Motor inrush conditioning on first use: On first use, run your CXT tool at half load for two cycles before full torque applications. This lets the BMS profile the motor's inrush current spike and set overcurrent thresholds accurately — reducing the chance of a false trip during heavy cuts or fastening sequences later.
BMS cutoff on CXT drill or saw motor-start inrush surge
When you pull the trigger hard on a CXT drill or circular saw, the motor draws a spike of current well above its running draw — often three to five times higher in the first milliseconds. If the BMS has not yet profiled that motor's inrush signature, it can read the spike as a fault and cut power immediately. This is more common on a fresh pack straight from storage. Two partial-load cycles give the BMS enough data to distinguish a normal start surge from a genuine overcurrent event. After conditioning, cold starts under full load should engage cleanly without a mid-pull cutout.
Charger stays red and never accepts the new pack after storage
Makita CXT chargers have a minimum acceptance voltage — if a cell drops below roughly 2.5V per cell during extended storage, the charger rejects the pack rather than risk charging a damaged cell. This shows as a solid or blinking red light with no charge progression. To recover the pack, place it in a warm environment (above 15°C) for 30 minutes, then re-seat it firmly in the charger. If the charger still refuses to enter charge mode, check the terminal contacts for oxidation and clean with a dry cloth before retrying.