Gardena 18V Automower 115H Replacement Battery 2500mAh

Gardena Automower 115H — 18V Li-ion Replacement Battery

This 18V 2500mAh (45Wh) Li-ion battery fits the Gardena 8654121 pack and the Automower 115H robotic mower across the 2019, 2020, and 2021 model years, plus over 30 additional compatible units. It slots into the same bay as the original and communicates with the mower's onboard BMS using the same cell voltage and discharge profile. Voltage and capacity match the factory specification exactly.

• Automower 115H platform fit: The 115H uses a fixed 18V architecture with a dedicated BMS handshake. Every cell in this pack is matched to that voltage rail, so the mower's charge station and docking circuit recognise it without calibration errors or fault codes on re-dock.
• Bench tested on actual hardware: We cycled this pack through simulated blade-motor inrush loads — the kind the BMS sees when the 115H hits thick or wet grass. The protection circuit held steady at rated current without nuisance trips across all test cycles.
• Seasonal storage tip: Before storing the mower over winter, run the battery to roughly 40–50% charge and remove it from the unit. Storing a fully charged Li-ion pack at elevated state-of-charge accelerates cell degradation over months of inactivity.

Charger showing fault after the mower sat all winter

A Li-ion pack left in the mower through winter can self-discharge below the charger's acceptance threshold — typically under 2.5V per cell. The Gardena charge station sees this as a fault condition and refuses to begin the charge cycle. Some chargers include a trickle pre-charge mode that can recover the pack; if yours does not, hold the battery at room temperature (18–22°C) for several hours first, then reconnect. If cell voltage has dropped below 2.0V per cell, recovery is not guaranteed and replacement is the correct step.

Mower cuts out mid-row then restarts a few minutes later

This is thermal protection activating — not a faulty battery. When the blade motor draws sustained high current through dense or wet grass, cell temperature rises until the BMS trips the output circuit. The 115H will not restart until the pack cools below the reset threshold. Allow a five-minute cooldown with the mower stationary before resuming. If cut-outs happen repeatedly on normal grass in mild conditions, check that the blade is sharp — a blunt blade forces the motor to draw significantly more current for the same cut.