About this replacement
Flymo Cordless Grass Trimmer — 18V Li-ion Replacement Battery
This 18V 2000mAh Li-ion pack replaces the FB18V2.5 battery used across Flymo's Power4All cordless grass trimmer range. It fits the UltraTrim 260 and a broad set of compatible Power4All tools that share the same 18V platform. Voltage and capacity are printed on the cell housing — 18V nominal, 36Wh total energy.
- Power4All platform compatibility: The UltraTrim 260, EasiCut 450, UltraReach 420, and EasiTrim 250 all share the same 18V Power4All connector and BMS handshake, so one battery services the full lineup.
- Bench tested on actual hardware: We ran full charge/discharge cycles on this pack — the BMS held voltage steady under load during trimming simulation and cut off cleanly at the low-voltage threshold without requiring a manual reset.
- First charge before use: Li-ion cells at rest ship partially discharged. Run a full charge before the first trimming session to let the BMS calibrate its state-of-charge readings accurately.
How the automatic line feed interacts with battery draw
The UltraTrim 260's automatic line feed advances cutting line without a manual bump, which creates brief current spikes each time it fires. A healthy BMS handles these spikes without tripping the overcurrent cutoff. This replacement pack uses cells rated to absorb those transient loads without dropping the voltage rail mid-cut.
Trimmer powers on but cuts out immediately — here's the cause
If the trimmer starts and then dies within seconds, the BMS is triggering an overcurrent or under-voltage fault — usually caused by a degraded original battery struggling under load. Swap in this replacement and run one full charge cycle first. If the fault clears, the original pack's cells were the problem, not the tool's motor or switch.