Eibenstock EPG 400 A 18V Replacement Battery 6000mAh Li-ion

Eibenstock EPG 400 A — 18V Li-ion Replacement Battery

This 18V 6000mAh (108Wh) Li-ion battery replaces the original pack on the Eibenstock EPG 400 A cordless angle grinder. It fits the EPG 400 A, EPG 400 A ohne, and EPG 400 A ohne Akkus und Ladegerat variants. Same voltage rail, same connector footprint, same BMS communication protocol as the factory pack.

• EPG 400 A platform fit: All three listed EPG 400 A variants share the same 18V battery bay and BMS handshake protocol. The grinder's speed controller expects a specific discharge curve; cells here match that profile so the tool doesn't throttle mid-cut.
• Bench tested on actual hardware: We cycled this pack through repeated motor-start inrush events on an angle grinder platform. The BMS held overcurrent thresholds stable across cold starts and sustained grinding loads without tripping.
• Motor inrush conditioning: On first use, run the grinder at half load for two cycles before full-depth cutting or heavy grinding. This lets the BMS log the motor's inrush current signature and calibrate overcurrent protection thresholds before you push the tool hard.

BMS cutoff on EPG 400 A motor-start inrush surge

The EPG 400 A draws a brief high-current spike every time the trigger is pulled from rest — this inrush can reach three to five times the normal running current. A BMS that hasn't profiled the motor yet may read that spike as a fault and cut the pack. Cells with higher cold internal resistance make this worse, especially below 10°C. Warming the pack to room temperature before use and completing two light conditioning cycles reduces false cutoff events.

Grinder bogs under load after several cuts in a row

Sustained grinding heats both the motor and the battery cells inside the EPG 400 A's enclosed housing. As cell temperature rises, internal resistance increases and the voltage rail sags under load — the grinder loses torque and slows. This is not cell failure; it is thermal voltage sag. Let the pack rest for three to five minutes between heavy cutting sessions and check that the battery contacts are clean and fully seated — dirty contacts add resistance and make sag worse at the same load level.