Fuxtec FX-RB218 Replacement Battery 28V 5000mAh Li-ion

Fuxtec FX-RB218 / FX-RB224 — 28V Li-ion Replacement Battery

This is a 28V Li-ion battery rated at 5000mAh (140Wh), built to fit the Fuxtec FX-RB218 and FX-RB224 cordless lawn mowers. It slots into the same battery bay as the original pack and communicates with the mower's onboard BMS using the same handshake protocol. Voltage and capacity match the factory specification exactly.

• FX-RB218 and FX-RB224 compatibility: Both mowers run the same 28V battery platform and share an identical connector and BMS communication line. One pack fits both machines without adapters or firmware changes.
• Bench tested on actual hardware: We cycled this pack under simulated blade-motor load conditions. The BMS held steady through repeated inrush events and stepped down correctly at the low-cell threshold — no false trips on a fully conditioned pack.
• Seasonal storage tip: Before storing the mower for winter, charge the pack to around 50–60% — not full. A fully charged Li-ion pack sitting at 28V for several months accelerates cell degradation faster than a partial charge does.

BMS cutoff on thick-grass and wet-grass blade load

The FX-RB218 blade motor draws a sharp inrush current each time it bites into dense or wet grass. If the battery's cells are partially depleted, internal resistance rises and the voltage sag during that inrush can cross the BMS under-voltage trip point. The mower shuts down mid-row as a protective response, not a fault. Keeping the pack above 30% charge before tackling heavy cuts reduces the frequency of these trips significantly.

Charger not accepting the pack after winter storage

If the mower sat in a cold garage all winter with a discharged pack, individual cells can drift below the charger's acceptance threshold — typically around 2.5V per cell on a 28V Li-ion pack. The charger reads this as a fault condition and refuses to begin the charge cycle. Bring the pack indoors and leave it at room temperature for several hours first. Most chargers will then detect the cells are within recoverable range and begin a trickle pre-charge back up to the 3.0V acceptance level.