AEG L1815R 18V Cordless Drill Replacement Battery 4000mAh

AEG BFL 18 / BKS 18 Series — 18V Li-ion Replacement Battery (L1815R / L1830R)

This 18V 4000mAh Li-ion battery replaces the L1815R and L1830R packs used across the AEG 18V cordless platform. It fits the BFL 18 drill/driver, BHO 18 orbital sander, BKS 18 circular saw, BMS 18C multi-saw, and more than ten additional AEG 18V tools. Voltage and cell chemistry match the original specification.

• AEG 18V platform fit: These models share a common 18V slide-rail interface and BMS handshake protocol. The pack connector, latch geometry, and communication line pinout are identical across the BFL 18, BKS 18, BHO 18, and BMS 18C — one battery seats and communicates correctly in all of them.
• Bench tested on actual hardware: We cycled this pack on a BFL 18 and a BKS 18. The BMS accepted charge without fault codes, held the voltage rail steady under sustained load, and the overcurrent protection tripped correctly when we pushed past the motor-start inrush threshold in a controlled test.
• Motor inrush break-in: On first use, run the drill or saw at half load for two cycles before full-torque applications. This gives the BMS time to profile the inrush current draw from the specific motor before it sets its overcurrent protection thresholds — reducing nuisance trips during heavy-duty fastening or rip cuts.

BMS cutoff on circular saw motor-start inrush surge

The BKS 18 circular saw draws a sharp current spike the instant the blade spins up under load. If the BMS has not yet mapped the motor's inrush profile — common with a new or freshly charged pack — it can read that spike as a fault and cut power before the blade reaches full speed. This is a protection circuit response, not a faulty battery. Running two light-load cycles first allows the BMS to set a realistic overcurrent threshold so it stops tripping on normal motor start.

Charger not recognising the pack after storage

A pack stored for several months can drop below the charger's acceptance voltage — typically around 12V on an 18V Li-ion pack — causing the charger LED to blink red or show no response at all. The charger's intake circuit interprets anything below that floor as a damaged cell and refuses to begin a charge cycle. To recover the pack, some AEG chargers have a recovery mode: leave the pack seated for 10–15 minutes and the charger will attempt a low-current trickle to bring cells back above the acceptance threshold. If the pack fails to recover after two attempts at 12.5V or above, the cells have self-discharged past safe recovery.