About this replacement
GreenWorks 40V Chainsaw & Pole Saw — 40V Li-ion Replacement Battery
A 40V, 5000mAh (200Wh) lithium-ion battery built to fit GreenWorks 40V outdoor power equipment, including the 12" Chainsaw and 8" Cordless Pole Saw. Replaces part numbers GWG40B2 and GWG40B4. Slots into the same 40V platform that powers over 75 GreenWorks tools.
- Broad 40V platform compatibility: GreenWorks standardized the connector, voltage rail, and BMS handshake across the 40V lineup, so one battery covers chainsaws, pole saws, and dozens of other tools sharing the same platform.
- Bench tested on actual hardware: We ran full charge/discharge cycles — the BMS held voltage steady under cutting load and tripped cleanly at the low-voltage cutoff without dropping the tool mid-cut.
- First charge after storage: If the battery has been sitting, run a full charge before first use — Li-ion cells partially discharged in storage need one complete cycle to recalibrate capacity reporting on the charger.
Why capacity matters on a chainsaw pulling sustained load
Chainsaws draw hard, uneven current — especially through knots or dense limbs. A 5000mAh cell pack handles those current spikes without the BMS tripping an overcurrent fault. Smaller capacity packs on the same voltage can shut the tool down mid-cut when load spikes. The 200Wh total energy rating here gives the BMS more headroom to manage those peaks.
Battery not recognized by the charger — here's why
GreenWorks 40V chargers handshake with the battery's BMS before starting a charge cycle. If the charger flashes an error and won't start, the cells may have discharged below the BMS recovery threshold during shipping. Connect the battery for 30 seconds, disconnect, then reconnect — this wakes the protection circuit and allows the charger to establish communication and begin charging normally.