Robomow 753-11203 18.5V Replacement Battery RK 1000

Robomow RK 1000 / RK 2000 Series — 18.5V Li-ion Replacement Battery (753-11203)

This is an 18.5V 3200mAh (59.2Wh) lithium-ion battery for the Robomow RK 1000, RK 2000, and RK 2000 Pro robotic lawn mowers. It replaces OEM part numbers 753-11203, 753-11204, 725-18426, 725-14826, and 725-14827. Fit the battery into the mower's battery compartment — no tools required.

• RK 1000 and RK 2000 series fit: All models listed share the same 18.5V battery rail, physical form factor, and BMS handshake protocol. The connector and cell configuration are identical across the RK 1000, RK 2000, and RK 2000 Pro — one battery fits all three.
• Bench tested on actual hardware: We ran this pack through full charge and discharge cycles on the RK 1000 platform. The BMS communicated correctly with the mower's charge management circuit, accepted charge without fault codes, and held voltage through simulated blade-load conditions.
• Seasonal storage tip: Before first use in spring, bring the battery indoors overnight if temperatures are below 10°C. Cold Li-ion cells carry higher internal resistance, and the blade motor's inrush current can trip the BMS on a cold pack before the mower cuts a single row.

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

When the RK 1000 crosses a dense or wet patch, the blade motor draws a short inrush spike — sometimes 2–3× the steady-state current. If the battery's state of charge is below roughly 30%, the BMS sees cell voltage sag past its lower trip threshold and cuts power to protect the cells. The mower stops, then recovers once voltage rebounds. Keeping the pack above 40% charge before long mowing sessions reduces these mid-cycle shutdowns.

Charger shows fault light after mower sat all winter

Robomow chargers reject packs whose cell voltage has dropped below approximately 14V — a threshold built into the charger's acceptance circuit to flag potentially damaged cells. After months in an unheated garage, self-discharge can push the pack below that level. To recover the battery, connect it to the charger and hold the charger's reset button for 10 seconds if that option is present on your unit; alternatively, leave it connected for 30 minutes — many chargers will trickle-charge back up to acceptance voltage before switching to normal charge mode. If cell voltage has fallen below 10V, recovery is unlikely and the pack should be replaced.