About this replacement
Flymo Cordless Grass Trimmer — 18V Ni-MH Replacement Battery
An 18V, 1500mAh Ni-MH replacement battery for Flymo cordless grass trimmers and garden tools. Fits the Contour Cordless XT, Easicut 420, Easicut 500, and SimpliStore 300, among others. Voltage and capacity match OEM spec at 27Wh total energy.
- Shared platform compatibility: These Flymo models run the same 18V Ni-MH battery rail with a common connector and matching BMS charge profile, so one pack serves the full range.
- Bench tested on actual hardware: We ran full charge/discharge cycles — the BMS held voltage stable under load and released cleanly at the low-voltage cutoff without tripping a false protection fault.
- First charge after storage: Ni-MH packs that have sat unused for months may show reduced initial capacity. Run two or three full charge/discharge cycles through the Flymo charger before judging performance — capacity recovers as the cells re-condition.
Why Ni-MH chemistry behaves differently to lithium in garden tools
Ni-MH cells have a flatter discharge curve than lithium. The trimmer may feel like it is fading gradually rather than cutting off sharply — that is normal behaviour for this chemistry. Temperature affects Ni-MH more than lithium; avoid charging immediately after heavy use. Let the pack cool to ambient temperature first to protect cell longevity.
Trimmer head slows under load — battery or motor?
If the cutting head bogs down on light grass, the cause is usually a pack that has voltage-sagged from age or deep discharge, not a motor fault. Check the pack voltage under load with a multimeter — a healthy 18V Ni-MH should hold above 15V during use. A replacement pack at full capacity restores full line speed. If the head still slows on a fresh, fully cycled battery, inspect the trimmer head for line feed blockages before suspecting the motor.