Haaga 355 Accu 18V Replacement Battery 6000mAh Li-ion

Haaga 355 accu — 18V Li-ion Replacement Battery

This is an 18V Li-ion battery rated at 6000mAh (108Wh), built to replace the original pack on the Haaga 355 accu walk-behind sweeper. The 355 accu is a motorized outdoor sweeper used on driveways, parking lots, and pathways. This replacement fits the same battery slot and connects to the same charging system as the factory pack.

• Haaga 355 accu brush motor compatibility: The 355 accu runs a motorized brush system that draws short inrush spikes on start-up. This pack's BMS is calibrated to handle that startup current without tripping, which matters if a previous battery was cutting out before the brushes reached full speed.
• Bench tested on actual hardware: We ran this pack through repeated brush-motor start cycles and monitored cell voltage under sustained sweeping load. The BMS held rail voltage steady and did not trigger overcurrent cutoff during start-up inrush or continuous operation.
• First-use load cycling on the 355 accu: Run the sweeper at a light pace for the first two full charge cycles before using it on heavy debris loads. This lets the BMS log the motor's inrush current signature and set accurate overcurrent thresholds before full brush engagement.

BMS cutoff on brush motor start-up in cold conditions

Li-ion cells see a significant rise in internal resistance below 5°C. On the 355 accu, that means the voltage rail sags harder during brush motor inrush when the battery is cold. If the sag crosses the BMS undervoltage threshold before the motor reaches running speed, the pack cuts out entirely. Bring the battery to room temperature before sweeping in near-freezing conditions — above 10°C, internal resistance drops enough that the BMS stays out of the way through the inrush spike.

Charger not recognising the new pack after storage

If the replacement pack has been sitting in a warehouse, cell voltage can drop below the charger's acceptance threshold — typically around 2.5V per cell. The Haaga charger may show a fault light or simply do nothing when the pack is inserted. Most chargers have a recovery or "wake-up" mode: leave the pack on the charger for 10–15 minutes without removing it, and the charger will trickle charge the cells back up to acceptance voltage. If the charger still shows a fault after 20 minutes, check that all pack contacts are clean and making solid connection — a resistance reading above 0.1 ohm at the contact points will block the handshake.