About this replacement
Worx WG150s / WG541 Series — 18V Ni-MH Replacement Battery (WA3127)
This is an 18V, 1300mAh Ni-MH replacement battery for the Worx WG150s, WG152, WG250, and WG541 cordless string trimmers. It replaces OEM part WA3127 and slots directly into the battery bay on these lightweight residential trimmers. Voltage and connector match the original Worx specification at 18V / 23.4Wh.
- WG150s, WG152, WG250, WG541 platform fit: These four trimmer models share the same 18V battery bay, connector pinout, and BMS communication protocol. One replacement covers the whole platform — no adapter or wiring change needed.
- Bench tested on actual hardware: We cycled this pack through charge and discharge on the WG150s platform. The BMS negotiated correctly with the Worx charger, cell balancing completed without fault codes, and discharge held steady across the full cycle.
- Ni-MH motor-start conditioning: For the first two uses, run the trimmer at partial throttle before full cutting loads. Ni-MH cells have higher internal resistance when new, and easing into motor-start inrush lets the BMS profile the draw before locking its overcurrent threshold.
Charger blinking red on a new or stored WA3127 pack
Worx chargers for the 18V platform check cell voltage before starting a charge cycle. If a Ni-MH pack has self-discharged below roughly 1.0V per cell during storage, the charger rejects it and flashes red. This is a charger acceptance threshold, not a dead battery. To recover, connect the pack and hold the charger button for 10 seconds to force a trickle-charge recovery mode, or use a bench charger set to 0.1C until the pack climbs above the acceptance floor — typically 14–15V pack total.
Trimmer bogs under load mid-cut despite a full charge indicator
Ni-MH cells show voltage sag under sustained motor draw — the pack voltage drops under load even when resting voltage reads full. On the WG150s, thick grass or repeated edging passes pull enough current to sag the rail below the motor controller's minimum, causing the trimmer to slow or stall. First, check the battery bay contacts for oxidation — Ni-MH packs corrode terminals faster than Li-ion. Clean contacts with isopropyl alcohol, then re-test; if sag continues, check that charger termination actually completed by confirming the green light held for at least 30 seconds before removal.