Mowox BA 573 Replacement Battery 20V 2500mAh Li-ion

Mowox RM 1000 WiU-SN Series — 20V Li-ion Replacement Battery (BA 573)

This is a 20V 2500mAh (50Wh) Li-ion replacement for the Mowox BA 573 battery pack. It fits the RM 1000 WiU-SN, RM 500 WIU-SN, RM 700 BTU-SN, and RM 900 WiU-SC cordless mowers. The pack slots into the same battery bay and communicates with the mower's onboard BMS over the same connector pinout.

• RM 500 / 700 / 900 / 1000 series compatibility: All four models run a shared 20V battery platform with the same physical connector and BMS handshake protocol. Mowox standardised this across the range so the same pack works in each chassis without adapter hardware.
• Bench tested on actual hardware: We ran the pack through full charge and discharge cycles, monitoring cell voltage balance and BMS cutoff thresholds under simulated blade-motor inrush loads. The protection circuit responded correctly at over-current and over-temperature limits without false trips under normal mowing loads.
• Seasonal storage tip: Before first spring use, 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 on startup can trip the BMS on a pack that hasn't warmed to room temperature.

BMS cutoff during thick-grass or wet-grass blade load

The blade motor on these mowers draws a sharp current spike when it bites into dense or wet grass. If pack voltage sags below the BMS's lower threshold during that spike, the protection circuit trips and the mower shuts off. This isn't a faulty battery — it's the BMS doing exactly what it should. Keeping the blade clear of accumulated clippings reduces motor drag and lowers the peak current draw that triggers the cutoff.

Charger shows fault light after mower sat unused all winter

Li-ion cells self-discharge slowly over months. If the pack dropped below roughly 2.5V per cell during winter storage, the charger's input-voltage check will reject it and flash a fault code rather than begin charging. Some chargers recover a deep-discharged pack by applying a brief trickle current — check your charger manual for a "recovery" or "boost" mode. If no recovery mode exists, try a short 5–10 minute charge attempt, then disconnect and reconnect the pack to prompt the charger to re-poll cell voltage.