Mr.Gardener MR 400 Replacement Battery 28V 5000mAh

Mr.Gardener MR 400 / MR 600 / MR 1000 / MR 1200 — 28V Li-ion Replacement Battery (862615)

This 28V 5000mAh (140Wh) Li-ion battery replaces OEM part numbers 862615 and 862618 in the Mr.Gardener MR 400, MR 600, MR 1000, and MR 1200 cordless lawn mowers. All four models share the same 28V battery platform, connector format, and BMS handshake protocol. Drop it in and the mower's original charger recognises the pack without any reconfiguration.

• MR 400 / MR 600 / MR 1000 / MR 1200 platform: These mowers run a shared 28V rail with the same blade motor driver and connector housing. One battery part number covers the entire range because the BMS communication signal and physical fitment are identical across all four.
• Bench tested on actual hardware: We cycled this pack under simulated blade-motor inrush loads and confirmed the BMS holds the discharge rail without nuisance tripping under normal cutting conditions. Cell balancing activates correctly on the first full charge cycle.
• Seasonal storage tip: Before the first mow of spring, bring the battery indoors overnight if the garage temperature is below 10°C. Cold Li-ion cells have elevated internal resistance — the blade motor's inrush current on a cold pack can trip the BMS before the cells warm up, making the mower appear faulty when the battery is fine.

BMS cutoff during thick-grass or wet-grass cuts

The MR-series blade motor draws significantly more current through dense or damp grass than on a dry, even lawn. If the instantaneous current pull exceeds the BMS protection threshold, the pack disconnects the output rail to prevent cell damage. This is not a battery fault — it is the protection circuit doing its job. Let the mower sit for five minutes, then restart on a lighter pass to allow the BMS to reset and the cells to recover.

Charger shows fault light after the mower sat unused all winter

Li-ion cells self-discharge slowly during long storage. If the pack voltage drops below roughly 2.5V per cell, most chargers refuse to begin a charge cycle because the BMS flags the pack as under-voltage. Connect the battery to the charger and leave it for 15–30 minutes — some chargers include a trickle pre-charge mode that recovers cells from this state. If the fault light clears and the charger begins normal charging, the pack has recovered. If the fault persists after 30 minutes, the cells have been in deep discharge too long and the pack will need replacement.