About this replacement
Bosch GWS 18 V-LI / GSR 18 Series — 18V Li-ion 2000mAh Replacement Battery (BAT609 / 2 607 336 091)
This is an 18V Li-ion replacement battery pack rated at 2000mAh (36Wh), built to the same voltage rail and connector spec as the original Bosch BAT609 and BAT610G packs. It fits the GWS 18 V-LI angle grinder along with GSR 18-2-LI, GSR 18 VE-2-LI, GSR 18 V-LI, and over 30 additional Bosch 18V tools in the same platform. OEM part numbers covered include BAT609, BAT609G, BAT610G, BAT618, BAT618G, BAT620, BAT622, BAT611, 2 607 336 091, 2 607 336 092, and related variants.
- Bosch 18V platform fit: Every model on this compatibility list runs the same 18V rail, uses the same slide-in connector, and communicates with the same BMS handshake protocol. The charger reads cell temperature and state-of-charge from the pack before allowing charge current — the electronics here respond to that handshake correctly.
- Bench tested on actual hardware: We ran this pack through charge-discharge cycles on an 18V Bosch platform tool, monitoring BMS cutoff behaviour under inrush current at trigger pull and under sustained load. Cell voltage balance across the pack stayed within 20mV at full charge, and no false overcurrent trips were recorded during motor start.
- Break-in load cycling on the angle grinder: On first use, run the GWS 18 V-LI at half load for two cycles before any heavy grinding or cutting applications. This gives the BMS time to profile the grinder's motor inrush draw and calibrate its overcurrent protection threshold before you put the tool under full disc load.
BMS cutoff on motor-start inrush during trigger pull
Angle grinders pull a sharp current spike the instant the motor spins up — on the GWS 18 V-LI, that inrush can hit 30–40A for a fraction of a second. A new pack fresh from storage may have a BMS that hasn't yet learned the motor's inrush profile, causing it to trip the overcurrent protection and cut power mid-start. If this happens, release the trigger immediately, wait five seconds, then pull again at a gentler ramp. After two or three controlled start cycles the BMS sets a learned threshold and the problem stops.
Charger blinking red and refusing to accept the pack after storage
Li-ion cells sitting unused drop toward a storage voltage of around 3.6–3.7V per cell. If they fall below approximately 3.0V per cell, most Bosch chargers reject the pack with a continuous or rapid red blink — they won't push charge current into cells they read as potentially damaged. To recover, check the pack terminal voltage with a multimeter; if the total reads above 14.4V (eight cells at 1.8V each), place the pack in the charger and hold the pack contacts against the charger terminals manually for 10–15 seconds to trigger wake-up current. If the total reads below 10V, cell recovery is unlikely.