About this replacement
Flymo Grass Trimmer & Lawn Edger — 18V Li-ion Replacement Battery
This 18V 2500mAh Li-ion battery replaces part numbers 577507001 and CCT250-3 across a range of Flymo cordless garden tools. It fits the Contour Cordless XT — a 2-in-1 grass trimmer and lawn edger — along with the Easicut 420, Easicut 500, and SimpliStore 300. Rated at 45Wh, it matches the original voltage rail these tools require.
- Cross-model compatibility — Flymo 18V platform: The Contour Cordless XT, Easicut, and SimpliStore models share the same 18V connector and BMS handshake, which is why one battery pack covers the full range.
- Bench tested on actual hardware: We ran full charge/discharge cycles — the BMS held voltage steady under trimmer load and cut off cleanly at the low-voltage threshold without tripping a fault state.
- First charge after storage: If the pack has been sitting, run a full charge before first use — Li-ion cells at low state of charge benefit from a complete conditioning cycle before being put under load.
Why voltage stability matters for automatic line feed
The Contour Cordless XT uses an automatic dual-line feed system that advances line based on motor speed sensing. Voltage sag from a weak or mismatched battery can cause the system to misread motor load and overfeed or underfeed line. A stable 18V delivery keeps the feed mechanism responding correctly. This pack's BMS actively regulates output to stay within the motor's expected voltage window.
Trimmer not turning on after battery swap — here's the fix
If the trimmer stays silent after fitting the new battery, the BMS may have shipped in a protective sleep state triggered by low cell voltage during transit. Seat the battery fully, connect it to the charger for 10–15 minutes, then retry. A solid charge indicator confirms the cells have woken and the pack is ready to use.