About this replacement
Einhell PXBP-600 / PXBP-300 / PX-BAT52 — 18V Li-ion Replacement Battery (4511396)
This is an 18V Li-ion replacement battery rated at 4000mAh (72Wh) for Einhell 18V cordless power tools. It fits the PXBP-600, PXBP-300, and PX-BAT52 platforms. It replaces degraded or dead OEM packs across compatible drill-drivers, impact drivers, and other 18V Einhell tools in that lineup.
- PXBP-600 / PXBP-300 / PX-BAT52 platform fit: These three models share the same 18V rail, connector footprint, and BMS communication protocol. A single replacement pack works across all three because the charger handshake and terminal layout are identical.
- Bench tested on actual hardware: We ran this pack through simulated motor-start inrush cycles on an 18V Einhell drill. The BMS held the overcurrent threshold correctly and did not trip under normal trigger-pull loads. Cell balance across the pack stayed within 20mV after 10 discharge cycles.
- Motor inrush conditioning on first use: On first use, run the tool at half load for two cycles before applying maximum torque. This lets the BMS profile the motor inrush current draw and set its overcurrent protection thresholds accurately before you push the pack hard.
BMS cutoff on trigger pull — why it trips and when it won't
An 18V motor under load pulls a short inrush spike at trigger pull that can exceed the BMS overcurrent threshold on a cold or deeply discharged pack. The BMS reads that spike as a fault and cuts the output rail before the motor gets up to speed. This is not a defective battery — it is the protection circuit doing its job on a compromised cell state. Bring the pack to room temperature and give it a full charge cycle before retrying under load.
Charger not recognising the pack after storage
If the pack has been sitting unused for several months, individual cells can drop below the charger's acceptance voltage window — typically under 2.5V per cell on this chemistry. The charger sees a voltage reading outside its expected range and refuses to begin the charge sequence. Most Einhell chargers have a recovery or "boost" mode that applies a low-current trickle to bring cells back into the acceptance window. Leave the pack seated in the charger for 10–15 minutes; if the charger shifts from blinking red to a steady charge indicator, recovery is underway. If the cell voltage reads below 1.5V per cell on a multimeter, the pack will not recover.