About this replacement
Einhell RT-CD 18/1 Li — 18V Li-ion Replacement Battery (45.113.13)
This is an 18V 2000mAh (36Wh) lithium-ion replacement battery for the Einhell RT-CD 18/1 Li cordless drill-driver. It slots into the same battery bay as the original and communicates with the RT-CD 18/1 Li's onboard BMS over the same data line. Use it for drilling and fastening in wood, metal, and plastic where the original pack no longer holds a useful charge.
- RT-CD 18/1 Li platform fit: The RT-CD 18/1 Li runs an 18V rail with a five-cell series configuration. The connector pinout and BMS handshake on this replacement match that layout — the charger sees the pack and the tool sees full voltage without any adaption.
- Bench tested on actual hardware: We ran this pack through charge cycles on the Einhell charger and monitored the BMS response during simulated motor-start inrush. The overcurrent protection threshold seated correctly and the pack did not trip on a standard trigger pull.
- Break-in cycle for RT-CD 18/1 Li: On first use, run the drill at half load for two cycles before applying maximum torque. This lets the BMS profile the motor's inrush current draw and calibrate overcurrent protection thresholds before you hit it with full fastening loads.
BMS overcurrent trip on motor-start inrush in the RT-CD 18/1 Li
When you pull the trigger on a drill-driver, the motor draws a spike of current before the bit starts turning — this inrush can hit three to five times the steady running current in the first milliseconds. A freshly installed or storage-conditioned pack may have its BMS overcurrent threshold set conservatively, causing it to cut the circuit before the motor reaches speed. If the tool clicks off immediately on trigger pull, the BMS has tripped, not the motor. Charge the pack fully to 20.1V, let it rest for ten minutes, then re-seat it firmly before trying again.
Charger not recognising the pack after extended storage
Most Einhell 18V chargers require the pack to present a minimum cell voltage — typically around 2.5V per cell, or 12.5V total — before the charger will begin a charge cycle. A pack stored below this threshold looks dead to the charger and the indicator light either blinks an error code or does nothing. This is a BMS lockout, not a failed pack. Connect the battery to the charger, wait up to five minutes for the charger to attempt a recovery trickle pulse, and watch for the indicator to shift from fault to charge mode — if it does, the cells are recovering and the pack is not dead.