Haaga 355 accu 18V Li-ion Replacement Battery 2000mAh

Haaga 355 Accu — 18V Li-ion Replacement Battery

This 18V Li-ion battery replaces the original pack on the Haaga 355 accu cordless push sweeper. It delivers 2000mAh (36Wh) to power the rotating brush mechanism used for clearing driveways, patios, and outdoor surfaces. Slot it into the same bay as the original and the sweeper runs as normal.

• Haaga 355 accu compatibility: The 355 accu runs an 18V rail with a compact slide-in connector. This pack matches that rail voltage and connector geometry, so the BMS handshake completes and the brush motor receives full drive current without error codes.
• Bench tested on actual hardware: We cycled this pack through repeated brush-start events on the 355 platform. The BMS handled inrush current from cold starts without tripping, and cell voltage held steady across sustained sweeping passes.
• Cold-start brush engagement: Below 5°C, Li-ion internal resistance rises sharply. Let the battery warm to room temperature before use on frosty mornings — cold starts pull higher inrush current from an already-resistive cell, which can trigger the BMS overcurrent threshold prematurely and cut brush engagement before the sweeper clears the first pass.

BMS cutoff on brush motor start inrush in the 355 accu

The 355 accu brush motor pulls a short inrush spike the moment it engages — this is normal, but a degraded or deeply discharged pack can trip the BMS overcurrent threshold on that spike before the motor reaches steady-state draw. The result is an immediate shutoff that looks like a dead battery even when the pack shows partial charge. A new pack with fresh cells handles the spike cleanly because internal resistance stays low enough to absorb it without the BMS intervening. If the sweeper cuts out on the first press of the start lever, low cell voltage rather than mechanical fault is almost always the cause.

Charger not recognising the new pack after storage

If the charger shows no light or a blinking fault LED when you seat a new pack, cell voltage has likely dropped below the charger's acceptance threshold during shelf storage — typically around 2.5V per cell on an 18V Li-ion pack. Most Haaga-compatible chargers won't initiate a full charge cycle below that threshold as a protection measure. Some chargers have a recovery or "wake" mode — hold the pack seated for 30–60 seconds and the charger may trickle enough current to lift the cells above the acceptance floor. If that doesn't work, check cell voltage with a multimeter; any cell reading below 2.5V confirms a deep-discharge state requiring a recovery charge rather than a standard cycle.