Eibenstock EPG 400 A Replacement Battery 18V 3000mAh Li-ion

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

This 18V 3000mAh (54Wh) Li-ion battery fits the Eibenstock EPG 400 A cordless angle grinder, including the EPG 400 A ohne and EPG 400 A ohne Akkus und Ladegerat variants. It slots into the same battery bay and connects to the same 18V rail as the original pack. Voltage and cell chemistry match the tool's BMS handshake requirements.

• EPG 400 A platform fit: All three EPG 400 A variants share the same 18V battery bay geometry and BMS communication protocol. The connector pinout and latch mechanism are identical across the range, so one battery works across all three configurations without modification.
• Bench tested on actual hardware: We cycled this pack through repeated motor-start inrush events on an 18V platform and monitored BMS response. The overcurrent threshold held correctly on each trigger pull, and cell temperature stayed within spec under sustained grinding loads.
• Break-in load management: On first use, run the grinder at half load — light cutting or surface passes — for two cycles before full-depth grinding. This lets the BMS log the motor's inrush current signature and calibrate its overcurrent protection threshold before you hit peak torque.

BMS cutoff on the EPG 400 A during hard trigger pulls

Angle grinders draw a sharp current spike the instant the motor spins up from rest. On the EPG 400 A, this inrush can briefly exceed 20A on a cold or partially depleted pack. If the BMS reads that spike as a fault, it trips the overcurrent protection and cuts power mid-start. The fix is to ensure the battery is at or above 16V before use and to avoid cold starts — cells below 10°C show higher internal resistance, which amplifies the voltage dip and makes the BMS more likely to trip. A slow warm-up cycle resolves most cold-start cutouts.

Tool bogs under load mid-cut even with a charged battery

This is voltage sag — not a dead battery. Under sustained grinding pressure, cell internal resistance causes the pack voltage to drop below the tool's operating threshold, and the motor loses torque. Check the battery rail contacts on both the pack and the tool for oxidation or debris; even a thin film of metal dust raises contact resistance enough to worsen sag. Clean the contacts with a dry brush, seat the battery firmly, and verify open-circuit voltage reads at least 19.5V before the next use. If sag persists after contact cleaning, the pack's cells have capacity-faded beyond recovery.