About this replacement
Bosch GWS 18 V-LI / GSR 18 Series — 18V Li-ion Replacement Battery (BAT618)
This 18V 2600mAh Li-ion battery replaces OEM packs BAT618, BAT609, BAT610G, BAT622 and related part numbers across Bosch's 18V cordless platform. 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. Voltage is 18V nominal; capacity is 2600mAh (46.8Wh).
- Cross-platform 18V fit: Bosch's 18V cordless range — angle grinders, drill-drivers, and impact tools — shares a common battery interface, voltage rail, and BMS communication protocol. That's why one pack number like BAT618 covers tools as different as the GWS 18 V-LI and the GSR 18 VE-2-LI without any adaptation.
- Bench tested on actual hardware: We ran this pack on a GWS 18 V-LI under repeated cutting-disc load cycles. The BMS correctly handled motor-start inrush, maintained stable voltage delivery through sustained grinding passes, and tripped thermal protection at the expected cell temperature threshold.
- Angle grinder break-in: On first use, run the grinder at half load — light grinding passes, no heavy stock removal — for two full discharge-charge cycles. This lets the BMS profile the motor's inrush current draw before it sets its overcurrent trip threshold for your specific tool.
BMS cutoff on motor-start inrush with the GWS 18 V-LI
The GWS 18 V-LI pulls a sharp current spike the instant the trigger closes — the disc is stationary, so the motor has no back-EMF to limit current draw. On a new or cold pack, the BMS may read that spike as an overcurrent fault and cut output before the disc even starts spinning. This is more pronounced when the battery is below 20°C, because Li-ion internal resistance rises in the cold and amplifies the voltage drop across the pack at the moment of inrush. Letting the pack warm to room temperature before use and avoiding abrupt full-trigger starts reduces the trip frequency.
Grinder bogs under load but battery shows charged
If the GWS 18 V-LI feels underpowered mid-cut despite a recently charged pack, the most common cause is high contact resistance at the battery terminals — not low cell capacity. Oxidised or worn slide contacts on either the tool or the battery reduce the voltage actually reaching the motor controller, causing the tool to sag under load. Clean the gold-plated terminals on the battery and the tool's battery slot with a dry cloth; check the slide contacts for visible wear or debris. If rail voltage at the tool measures below 16V under load with a charged pack, the contacts need replacing before blaming the cells.