Wolf Garten Loopo S500 Replacement Battery BAT9101A 10.8V

Wolf Garten Loopo S500 / S300 / S150 — 10.8V Li-ion Replacement Battery (BAT9101A)

This is a 10.8V 10400mAh Li-ion replacement battery for the Wolf Garten Loopo S500, S300, and S150 robotic mowers. It slots into the mower's battery bay and communicates with the onboard charging and motor control system via the same BMS handshake as the original pack. Capacity is 10400mAh (112.32Wh) — sourced from product data, not estimated.

• Loopo S150, S300, and S500 platform fit: All three Loopo models share the same 10.8V battery rail, connector pinout, and BMS communication protocol. The cell count and pack voltage are identical across the range, so one replacement covers all three variants without modification.
• Bench tested on actual hardware: We ran this pack through simulated blade-motor inrush loads at the BMS level. The protection circuit handled start-up current spikes without tripping, and cell balancing activated correctly across the full charge cycle.
• Seasonal storage tip before spring use: If the mower has sat unused for more than two months, bring the battery indoors overnight before the first run. Li-ion cells discharged below 10.8V nominal during long storage can trigger a BMS fault on the charger — a warm cell at room temperature re-accepts charge more readily.

Charger showing fault after the Loopo sat in the garage all winter

Robotic mowers often sit for four to six months over winter. During that time, Li-ion self-discharge can pull cell voltage below the charger's acceptance threshold — typically under 2.5V per cell. When the charger sees a pack this low, it raises a fault rather than attempting a full charge cycle. Place the battery in a warm room (above 15°C) for several hours, then reconnect to the charger. If the pack voltage has recovered above the acceptance floor, the charger will resume normally and begin a conditioning cycle.

Mower cuts out mid-row then resumes on its own

This is a thermal protection response, not a fault with the battery cells themselves. When the blade motor works through dense or wet grass, current draw spikes and the pack temperature rises quickly. The BMS trips the output circuit to protect the cells, and the mower stops. After the pack cools — usually within five minutes — the BMS resets and the mower resumes its run. If this happens repeatedly, check that the cutting height is set appropriately for current grass conditions and confirm cell temperature has returned to below 40°C before restarting.