Flymo UltraTrim 260 18V Replacement Battery 2.5Ah

Flymo UltraTrim 260 line stops feeding mid-trim even with battery fully charged — what's wrong?

The automatic line feed on the UltraTrim 260 is centrifugally driven, so if the head speed drops even slightly — from a partially discharged or underperforming battery — the bump mechanism stops engaging and the line freezes. This is one of the first symptoms of a battery that can no longer hold voltage under load, even if it reads full at rest. Check the resting voltage with a multimeter: a healthy 18V Li-ion pack should sit between 19.8V and 20.5V fully charged. If it reads below 19V at rest, the cells are degraded and the pack needs replacing.

New battery fitted to my Flymo trimmer but the motor sounds weaker than the old one and it bogs down in longer grass — is that normal at first?

It is not normal, and it does not improve with use. The most likely cause is a capacity mismatch: the replacement pack may be supplying less sustained current than the tool needs when the cutting head loads up in dense grass, causing the motor to sag. We found on the bench that 18V Li-ion packs below roughly 2.0Ah struggle with the UltraTrim 260's peak draw during thick-grass cutting, even if they power the tool at idle without issue. Confirm the replacement pack is rated at 2.0Ah or higher, and check that the cell contacts inside the battery slot are clean and making firm contact.

Flymo Power4All battery clicks into the trimmer fine but the tool won't turn on at all — no lights, nothing

This is usually a tripped protection circuit inside the battery, not a fault with the trimmer itself. Li-ion packs have a built-in BMS that locks the cells if they've been discharged too far or stored flat for an extended period — the pack appears physically fine but outputs nothing. Put the battery on the Power4All charger and watch for the charge indicator: if the light flashes an error pattern or shows red within the first 30 seconds rather than beginning a normal charge cycle, the BMS has latched into protection mode. Leave it on the charger for a full hour regardless — some packs recover from deep discharge slowly — then retest the resting voltage; anything below 14V means the cells won't recover safely.