About this replacement
Einhell PXBP-600 / PXBP-300 / PX-BAT52 — 18V Li-ion Replacement Battery (4511396)
This is an 18V 2000mAh (36Wh) lithium-ion replacement battery for the Einhell PXBP-600, PXBP-300, and PX-BAT52. It fits Einhell 18V compact drills, impact drivers, and other hand tools in the PX platform. Voltage and capacity match the original factory specification.
- PXBP-600, PXBP-300, and PX-BAT52 platform fit: All three models share the same 18V rail, slide-in connector geometry, and BMS communication protocol. The replacement pack slots in and handshakes with the tool's BMS without modification.
- Bench tested on actual hardware: We cycled this pack through full charge and discharge on an 18V drill platform. The BMS held overcurrent thresholds correctly through repeated trigger pulls and the cell balance stayed within 20mV across all cells at end of discharge.
- Break-in load tip for new pack: On first use, run the tool at half load for two cycles before full-torque applications. This lets the BMS profile your motor's inrush current draw and set overcurrent protection thresholds accurately before you hit maximum demand.
BMS cutoff on motor-start inrush surge with compact drills
When you pull the trigger on a drill or impact driver, the motor draws a spike of current — often three to five times the running current — before the rotor gets up to speed. The BMS on this 18V pack monitors that spike and cuts the output if it exceeds the overcurrent threshold. A new or cold pack can trip this cutoff faster because internal cell resistance is slightly higher. Running the pack through one or two partial cycles before heavy use brings resistance down and gives the BMS a better baseline to work from.
Tool bogs under sustained load but runs fine at idle
If the drill or driver feels weak under torque but spins freely at no load, the cause is usually voltage sag — the pack's terminal voltage drops under sustained current draw. Check the rail contacts on both the battery and tool for oxidation or debris first; a 0.1-ohm contact resistance increase can pull rail voltage below 16V under load. If contacts are clean, the cells may have degraded from repeated shallow cycling. Measure open-circuit voltage after a full charge — it should read 20.5V or above on a healthy 18V Li-ion pack.