About this replacement
Husqvarna Modul-B / GSM-GPS — 3.7V Li-Polymer Replacement Battery (535 0636-01)
This 3.7V, 900mAh Li-Polymer battery replaces the original power cell in Husqvarna Modul-B and GSM-GPS systems. It matches OEM part numbers 535 0636-01, 535 0962-01, 575 24 24-01, 575 24 24-02, and 575 24 24-03. Dimensions are 50.25 x 30.92 x 6.40mm — a direct physical match to the factory cell.
- Modul-B and GSM-GPS platform fit: Both the Modul-B and GSM-GPS units share the same 3.7V cell footprint and BMS voltage thresholds. The connector pinout and physical envelope are identical across all five OEM part numbers listed above — no adapter or modification needed.
- Bench tested on actual hardware: We cycled this cell through charge and discharge on the Modul-B platform. The BMS accepted the pack without fault codes, held the nominal 3.7V rail cleanly, and the protection circuit triggered correctly at the low-voltage cutoff threshold.
- Seasonal storage tip: If the mower sits unused over winter, remove the Modul-B battery and store it at around 50% charge indoors. Leaving a Li-Polymer cell in a cold shed at low state-of-charge accelerates voltage drop below the BMS acceptance threshold — the charger will then refuse the pack in spring.
Charger showing fault after the mower sat in the garage all winter
Li-Polymer cells self-discharge slowly over months. If the pack drops below approximately 2.5V per cell, the charger's input detection circuit sees the voltage as out-of-range and throws a fault rather than beginning a charge cycle. This is a protection response, not a charger failure. Some chargers have a trickle or recovery mode — check the Husqvarna charger indicator sequence for a slow-flash pattern that signals recovery charging is active. If the charger shows no recovery mode and the pack reads below 2.5V on a multimeter, the cell has discharged beyond recoverable range and replacement is the correct step.
Mower cuts out mid-row then restarts a few minutes later
This points to thermal protection, not a faulty battery. The blade motor draws a surge of current through thick or wet grass, which heats the cell and trips the BMS over-temperature cutoff. The unit restarts once the cell cools — typically after a 5-minute pause. If this happens repeatedly in normal dry conditions, check that the battery contacts are clean and making full contact, since a high-resistance connection generates additional heat at the cell terminal. Allow a full 5-minute cooldown before resuming, and avoid running consecutive heavy-load passes without short breaks.