McCulloch 58V LI58GB Lawn Mower Replacement Battery 5000mAh

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

This is a 58V 5000mAh (290Wh) Li-ion replacement battery for the McCulloch LI58GB, LI58T, and LI58CS cordless lawn mowers. It slots into the same battery bay as the original and uses the same OEM part number 59-09.238.03. Capacity figures are taken from the product specification — not estimated.

• LI58GB, LI58T, and LI58CS compatibility: All three models run the same 58V drive platform with an identical battery bay, connector pin-out, and BMS communication handshake. The same pack works across all three without modification.
• Bench tested on actual hardware: We ran this pack through repeated blade-start cycles simulating thick-grass inrush current. The BMS held within spec at full load, and cell voltage stayed balanced across the discharge curve.
• Seasonal storage tip: Before putting the mower away for winter, charge the pack to around 50–60% — not full. A fully charged Li-ion pack sitting unused for months accelerates cell stress. Check voltage again in early spring before first use.

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

The LI58GB's blade motor draws a sharp inrush current each time it bites into dense or wet grass. If the BMS detects that current spike exceeding its protection threshold — typically caused by a combination of high load and elevated cell temperature — it cuts power to protect the cells. This is not a fault with the battery; it is the protection circuit doing its job. Let the pack rest for five minutes so cell temperature drops, then resume cutting at a slower pace through the heavy section.

Charger shows fault light after mower sat all winter

Li-ion cells that discharge below approximately 2.5V per cell over a long storage period will be rejected by a standard charger — the BMS blocks the charge cycle as a safety measure. Many chargers interpret this as a faulty pack and display a fault or red indicator light. To recover the pack, some chargers have a recovery or trickle mode that slowly brings cell voltage up to the acceptance threshold before switching to normal charge. If the charger has no recovery mode, the pack has likely dropped too far for safe reactivation and should be replaced.