About this replacement
Wolf Garten Li-ion Power GTB 815 Trimmer — 18V Li-ion Replacement Battery (Li-ion Power Pack 3)
This is an 18V, 2000mAh (36Wh) lithium-ion replacement battery for the Wolf Garten Li-ion Power GTB 815 cordless string trimmer. It replaces OEM part numbers Li-ion Power Pack 3 and 7420072. It also fits the Power HSA and GT815 platforms running the same 18V rail.
- GTB 815 / GT815 / Power HSA platform fit: These models share the same 18V battery rail, connector format, and BMS handshake protocol. One battery pack crosses all three without adapter changes or firmware mismatches.
- Bench tested on actual hardware: We ran this pack on the GTB 815 motor under repeated start-stop cycles. The BMS handled trigger-pull inrush current without tripping and held stable voltage through full cutting passes on dense grass.
- First-use motor profiling: On first use, run the trimmer at half throttle for two full cycles before tackling thick overgrowth. This lets the BMS record the motor's inrush current signature and set overcurrent thresholds accurately before you push maximum load.
BMS overcurrent trip on GTB 815 trigger pull
The GTB 815 motor pulls a sharp current spike the instant the trigger engages. If the BMS hasn't profiled that inrush yet — common with a new or fully rested pack — it can read the spike as a fault and cut output immediately. This is a protection response, not a defective battery. Run two half-load cycles first to let the BMS calibrate its overcurrent window to the motor's actual start profile.
Charger not recognising pack after storage
Li-ion cells that sit unused for several months can drop below the voltage threshold the charger uses to confirm a valid pack — typically around 2.5V per cell. When cell voltage falls under that floor, the charger refuses to begin a charge cycle and may blink an error. To recover the pack, place it in the charger and hold it there for 10–15 minutes; many chargers apply a low-current trickle to bring cells back above the 2.5V acceptance threshold before switching to normal charge mode.