Würth H 28-MA 28V Replacement Battery 4000mAh

Wurth H 28-MA Series — 28V Li-ion Replacement Battery (0700 956 730)

This 28V Li-ion battery pack replaces the OEM unit (part no. 0700 956 730) across the Wurth H 28-MA, BS 28-A Combi, Master 28V, and Master H 28-MA cordless tool platforms. Capacity is 4000mAh (112Wh). The cell voltage and connector match the original spec — no adapter required.

• H 28-MA platform compatibility: The H 28-MA, BS 28-A Combi, and Master 28V share the same 28V rail, battery footprint, and BMS communication protocol. One pack works across all four models without modification.
• Bench tested on actual hardware: We ran this pack through motor-start inrush cycles on drill and impact driver loads. The BMS held stable at the overcurrent threshold — no false trips on normal trigger pulls. Cell balance after full discharge came within 20mV across the pack.
• First-use load conditioning: On initial use, run the tool at half load for two full discharge-charge cycles before applying maximum torque or sustained impact driver loads. This lets the BMS profile the motor's inrush draw and set accurate overcurrent thresholds for your specific tool.

BMS cutoff on motor-start inrush with the H 28-MA drill

When you pull the trigger on a drill or impact driver, the motor draws a current spike two to four times higher than the running load — this lasts only milliseconds, but a cold or discharged BMS can read it as a fault. The protection circuit trips, and the tool goes dead mid-use. A BMS that hasn't profiled your motor yet is especially prone to this on the first few cycles. Running break-in cycles at reduced load lets the BMS learn the inrush signature and stops false cutoffs.

Charger not recognising the pack after storage

Li-ion cells that have sat unused for several months can drop below the charger's acceptance voltage — typically around 2.5V per cell. The Wurth charger sees the low voltage, flags it as a damaged or incompatible pack, and refuses to initiate a charge cycle. If the indicator blinks red and never transitions, the pack is likely below threshold. Most Wurth chargers have a recovery or "boost" mode — hold the pack on charge for 10–15 minutes and the charger will attempt a low-current pre-charge to bring cells back above 3.0V per cell before switching to normal charge.