Grizzly MR 400 28V Replacement Battery 5000mAh Li-ion

Grizzly MR 400 / MR 600 / MR 1000 / MR 1200 — 28V Li-ion Replacement Battery

This is a 28V, 5000mAh (140Wh) Li-ion replacement battery for the Grizzly MR 400, MR 600, MR 1000, and MR 1200 cordless lawn mowers. It slots into the same bay as the original pack and uses the same voltage rail, so the mower's electronics recognise it without reconfiguration. Capacity figures come directly from the product specification — not estimated from web sources.

• MR 400 / MR 600 / MR 1000 / MR 1200 compatibility: These four models share the same 28V platform and battery bay format. The connector pinout and BMS handshake protocol are identical across the range, so one battery covers all four without modification.
• Bench tested on actual hardware: We ran this pack through repeated blade-start cycles simulating dense grass load. The BMS held the voltage rail stable through motor inrush events and triggered thermal cutoff at the correct threshold — no false trips under normal cutting load.
• Seasonal storage tip: If the mower has sat unused since last season, do not put the battery straight on the charger in a cold garage. Bring it indoors and let it reach room temperature first. Cold Li-ion cells have elevated internal resistance, and charging a cold pack can trigger the BMS protection circuit before the cells are even warm.

BMS cutoff under thick grass or wet-grass blade load

The MR series blade motor draws a sharp inrush current every time it bites into a dense or wet patch. If the battery voltage sags below the BMS cutoff threshold during that inrush — typically caused by a worn or deeply discharged cell — the protection circuit kills the output instantly. A new pack with fresh cells handles this inrush without sag because internal resistance is low. If cutouts still occur, check that the blade is sharp; a blunt blade multiplies motor load and pushes even a healthy pack past its current limit.

Charger shows fault light after mower sat in garage all winter

Li-ion cells self-discharge slowly over months of storage. If the pack voltage drops below approximately 2.5V per cell, most chargers will refuse to charge it — this shows as a red fault light or no response from the charger at all. Some chargers include a recovery mode that applies a low trickle current to bring the pack back above the acceptance threshold. If yours does not, a compatible balance charger set to Li-ion recovery mode at 0.1A can often recover the pack to a chargeable state within an hour — confirm cell voltage has risen above 2.8V per cell before switching to normal charge mode.