Gardena 04025-20 Cylinder Mower Compatible Battery 25V 5000mAh

Gardena Accu-Spindelmaher 380 Li — 25V Li-ion Replacement Battery (04025-20)

This is a 25V Li-ion battery rated at 5000mAh (125Wh), built to replace the original pack in the Gardena Accu-Spindelmaher 380 Li cordless cylinder mower. It fits models listed under part numbers 04025-20, 8838, and 4025-00.640.00. The battery slots into the same port and connects to the same BMS handshake as the factory unit.

• 380 Li platform fitment: The Accu-Spindelmaher 380 Li and its variants — including the 648872 and Cylinder Lawnmower 380 Li — share the same 25V rail, connector, and BMS communication protocol. One pack covers the full range without adapter or modification.
• Bench tested on actual hardware: We ran this pack through full charge and load cycles, monitoring BMS response under simulated blade-motor inrush current. The protection circuit handled the start-up spike cleanly and held voltage within spec across the discharge curve.
• Seasonal storage tip: If the mower has sat unused through winter, bring the battery indoors overnight before first use. Below 10°C, Li-ion internal resistance rises sharply — the blade motor's inrush current at cold-start can trip the BMS on a pack that hasn't warmed to room temperature.

BMS cutoff under thick grass or wet-lawn blade load

The 380 Li's cylinder blade motor draws significantly more current when cutting dense or damp grass. If the BMS detects a sustained inrush above its threshold — common mid-row in wet conditions — it trips as a protective measure. The mower shuts off abruptly, but the pack itself is undamaged. Let the pack rest for five minutes, which allows the BMS thermal sensor to reset, then resume mowing at a slower walking pace.

Charger shows fault light after battery sat all winter

Li-ion cells left in a low-charge state over several months can discharge below the charger's acceptance voltage — typically around 2.5V per cell. The charger reads the pack as faulty and refuses to initiate a charge cycle. Some Gardena chargers include a recovery or conditioning mode; place the battery on charge and hold the charge button for ten seconds to trigger it. If the charger lacks that function, a compatible Li-ion recovery charger can bring individual cell groups back above 3.0V before normal charging resumes.