About this replacement
AEG BS 18C / BS 18G Series — 18V Li-ion Replacement Battery (L1815R)
This is an 18V Li-ion replacement battery rated at 6000mAh (108Wh), compatible with the AEG BS 18C, BS 18G, BKS 18, BFL 18, and over 28 additional AEG 18V platform tools. It uses OEM part numbers L1815R, L1830R, B1814G, and B1817. The battery slots into the same rail and connector as the original AEG pack.
- AEG 18V platform compatibility: The BS 18C, BS 18G, BKS 18, and BFL 18 all share the same 18V slide-rail connector and BMS communication protocol. Any battery on this platform must handshake correctly with the charger and tool PCB — this pack does both.
- Bench tested on actual hardware: We ran this pack through charge cycles on an AEG 18V charger and triggered load cycles on a BS 18C. The BMS responded correctly to inrush current on trigger pull and held voltage under sustained fastening loads without tripping.
- Motor inrush break-in: On first use, run the drill at half load — light fastening or low-torque drilling — for two full cycles before going to maximum torque or impact applications. This lets the BMS profile the motor's inrush current signature before locking in overcurrent thresholds.
BMS overcurrent trip on motor-start inrush in the BS 18C
The BS 18C's brushed motor draws a short current spike the instant you pull the trigger — this is normal inrush, but a new BMS with uncalibrated thresholds can read it as a fault and cut output. The pack shuts off in under a millisecond, and the tool goes dead mid-pull. Running two break-in cycles at reduced load trains the BMS to distinguish inrush from a genuine overcurrent event. After that, full-torque use proceeds without nuisance trips.
Charger shows blinking red and won't begin charging after storage
AEG 18V chargers reject packs where cell voltage has dropped below the acceptance threshold — typically around 2.5V per cell — due to self-discharge during storage. The charger blinks red rather than cycling into CC charge mode. Most AEG chargers include a recovery or "wake-up" mode: hold the pack in the charger for 10–15 minutes without removing it and the charger will attempt a low-current pre-charge to bring cells back above the acceptance floor. If the cells recover past 2.8V per cell, normal charging resumes automatically.