Gardena Sileno robotic mower battery rebuilding

Gardena Sileno robotic mowers use 18V Li-ion battery packs — the same Husqvarna Group platform found in Automower models, tuned for smaller gardens. Over time, lithium-ion cell capacity naturally declines, especially after 2–3 active seasons and winter storage periods. An OEM replacement battery from Gardena often costs 120–200 EUR, but that is not always necessary.

In our workshop we open the sealed battery pack, remove the worn cells and fit new premium 18650 lithium-ion cells. Each cell is individually tested and matched by internal resistance and capacity. After cell replacement we install a new BMS (battery management system) that ensures correct charging, discharging and cell balancing. Finally, the battery is fully charged and put through a load test to confirm that the rebuilt pack meets or exceeds factory specifications. All battery work carries a 6-month warranty.

Winter storage is the critical moment for a Gardena Sileno battery. If the robot is left with a fully discharged battery in a cold garage, the lithium cells can degrade irreversibly — a cell loses capacity or fails entirely. We recommend storing the robot in a dry room at 5–15 °C with the charge level at around 50–70 %. In spring, before the first mow, it is advisable to run one full charge-discharge cycle.

If your Gardena Sileno shows blinking LED codes, drains quickly or will not charge at all, these are typical signs of cell degradation or BMS failure. A charging loop (the robot begins charging and stops after a few minutes) usually points to one or more damaged cells causing cell imbalance. A corroded connector between the battery and the robot can cause intermittent power loss and sporadic errors. All of these problems are repairable — and a battery rebuild at our workshop costs significantly less than a new OEM pack.