McCulloch 58V LI58GB Cordless Lawn Mower Replacement Battery 3000mAh

McCulloch LI58GB / LI58T / LI58CS — 58V Li-ion Replacement Battery (59-09.238.03)

This is a 58V, 3000mAh (174Wh) lithium-ion replacement battery for the McCulloch LI58GB, LI58T, and LI58CS cordless lawn mowers. It slots into the original battery bay and communicates with the mower's BMS over the same data lines as the factory pack. OEM part number 59-09.238.03.

• LI58 platform compatibility: The LI58GB, LI58T, and LI58CS share the same 58V battery rail, connector pinout, and BMS handshake protocol. One pack covers all three mowers without any adapter or modification.
• Bench tested on actual hardware: We cycled this pack through simulated blade-motor inrush loads on the LI58 platform. The BMS held the connection through repeated high-draw events and balanced cells correctly across all charge cycles.
• Seasonal storage tip: If the mower has sat unused through winter, bring the battery indoors overnight before the first spring cut. Li-ion cells below 10°C carry higher internal resistance, and the blade motor's inrush current can trip the BMS on a cold pack before the deck even begins to spin.

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

The LI58 mower draws a sharp inrush current every time the blade motor bites into dense or wet grass. If the pack voltage sags below the BMS protection threshold during that inrush, the BMS trips and kills the deck instantly. This is a cell-health check, not a mower fault — a degraded original pack trips far earlier than a fresh one. A new pack at full charge holds well above the 48V cutoff floor the BMS monitors, so the deck stays running through the same grass conditions that stalled the old battery.

Charger showing a fault light after the mower sat through winter

A pack left in the garage from autumn to spring can self-discharge until individual cells drop below the charger's acceptance threshold — typically around 2.5V per cell. At that point the charger reads the pack as faulty and refuses to start a charge cycle. Some McCulloch chargers have a recovery or wake-up mode: leave the pack connected for 20–30 minutes and the charger may re-initiate once cells stabilise above the threshold. If the fault light persists after that window, the original pack has dropped too far to recover and replacement is the correct next step.