Gardena R40 18.5V Replacement Battery 1500mAh Li-ion

Gardena R40 / R80 Series — 18.5V Li-ion Replacement Battery (586 57 62-02)

This 18.5V Li-ion battery replaces the original pack in Gardena robotic lawn mowers including the R40, R50, R70, and R80. Capacity is 1500mAh (27.75Wh), matching the stock specification. It fits the same battery bay and connector as the factory unit.

• R40–R80 platform fit: These four mower models share the same 18.5V power rail, identical battery bay dimensions, and the same BMS handshake protocol. One battery design covers the full range because Gardena kept the electrical architecture consistent across this robotic series.
• Bench tested on actual hardware: We ran this pack through simulated blade-motor inrush loads at 18.5V. The BMS held the connection without nuisance trips on normal start cycles. Cell voltage stayed balanced across all three groups throughout discharge.
• Seasonal storage tip: Before returning the mower to service after winter, bring the battery indoors overnight if temperatures are below 10°C. Cold Li-ion cells carry higher internal resistance, and the blade motor's inrush current on a cold pack can trip the BMS on the first start of the season.

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

Gardena robotic mower batteries self-discharge slowly over winter. If the pack drops below approximately 2.5V per cell, the charger's acceptance circuit rejects it as a safety measure and shows a fault LED instead of beginning a charge cycle. This is a voltage threshold issue, not a faulty charger or dead battery. Some chargers include a trickle recovery mode — leave the pack connected for 30–60 minutes and check whether the fault clears once cells recover above the acceptance threshold.

Mower cuts out mid-row then resumes after a short pause

This pattern points to thermal protection triggering in the BMS, not a defective battery. Thick grass or wet conditions increase blade drag, which raises current draw and generates heat inside the pack faster than normal. The BMS disconnects the output to protect the cells, then re-enables once temperature drops. Allow a 5-minute cooldown, then resume — if cut-outs happen repeatedly on the same lawn section, check that the mowing schedule avoids peak midday heat.