About this replacement
Stiga A1500 / A3000 Series — 25.9V Li-ion Replacement Battery (381600608/0)
This 25.9V, 5000mAh Li-ion battery replaces the original pack in Stiga A1500, A3000, A500 Rtk, A5000, and compatible robotic and walk-behind cordless mowers. It matches the OEM voltage rail and connector so the mower's BMS communicates with the pack without errors. Capacity is 5000mAh (129.5Wh), identical to the factory specification.
- A1500 / A3000 platform fit: These models share the same 25.9V battery architecture, connector pinout, and BMS handshake protocol. Swapping between them uses the same pack — the charge controller reads cell state through the same communication line on all listed models.
- Bench tested on actual hardware: We ran this pack through simulated blade-motor inrush cycles, including the high-draw spike that occurs when the blade engages on startup. The BMS held without nuisance tripping across all five conditioning cycles.
- Seasonal storage tip: If the mower sat unused for more than three months, check the pack voltage before charging — if it has dropped below 20V, place it on the charger immediately rather than leaving it flat. Extended storage below the BMS recovery threshold will prevent the charger from accepting the pack at all.
BMS cutoff during thick-grass or wet-grass blade load
When the blade hits dense or wet grass, the motor draws a sharp current spike — often two to three times normal running current. If the pack's cells are below 20°C or partially discharged, internal resistance rises and the BMS may read that spike as an overcurrent fault and cut output. This is a protective response, not a fault with the battery. Let the mower sit for five minutes to allow the BMS to reset, then resume on a lighter pass. If it trips repeatedly in the same conditions, check that cells have been through at least three full charge-discharge cycles first.
Charger showing fault light after winter storage
Robotic mowers left docked or stored without a top-up charge through winter can drain the battery below the charger's acceptance threshold — typically around 17–18V for a 25.9V Li-ion pack. When cell voltage drops that low, the charger's fault light activates and charging will not begin. Connect the pack and watch the charger for 10–15 minutes — some units will attempt a slow recovery pulse at low current before switching to full charge. If the fault light stays on past 20 minutes, the cells have self-discharged past recovery and the pack needs replacement.