About this replacement
TomTom Spark Cardio + Music GPS — 3.7V Li-Polymer Replacement Battery (AHB332824HPS)
This 3.7V, 200mAh Li-Polymer cell is a direct replacement for the TomTom Spark Cardio + Music GPS and Spark Cardio 2 + Music GPS watches. It matches the OEM part number AHB332824HPS and fits the original battery bay without modification. Capacity figures come from the product data — 200mAh, 0.74Wh.
- Spark Cardio and Spark Cardio 2 compatibility: Both watch generations share the same 27.30 x 26.20 x 4.00mm battery bay, the same 3.7V voltage rail, and the same connector orientation. The BMS handshake on both platforms accepts this cell without triggering a protection lockout.
- Bench tested on actual hardware: We cycled this cell on a Spark Cardio + Music GPS unit with GPS active and heart rate monitoring running. The BMS accepted the new cell immediately and the fuel gauge IC initialised correctly after a full charge-to-100% cycle from near-zero.
- Post-swap charge protocol for the Spark platform: After fitting this cell, place the watch on its magnetic charger immediately and run it to 100% before first use. The fuel gauge IC on TomTom's Spark platform cannot establish an accurate charge reference without a complete charge cycle following a cell swap — skipping this step causes the gauge to read 0% or behave erratically from day one.
Why the Spark Cardio's GPS and HR sensors hit a new cell harder than expected in the first week
A fresh Li-Polymer cell has a slightly different internal impedance profile than a broken-in cell. The Spark's GPS chipset and optical heart rate sensor both draw pulse currents, and the BMS responds to those pulses against the new impedance curve — sometimes pulling back power delivery slightly until the cell is conditioned. This is normal and typically resolves within three to five charge cycles. If drain remains heavy after that point, check whether the watch's always-on display mode is active, as that setting alone accounts for a significant share of daily draw on this 200mAh cell.
Watch not pairing with phone after battery replacement
Removing the battery clears the active BLE session stored in the watch's volatile memory — the phone still holds the old pairing record, but the watch no longer recognises it. The fix is not to simply reconnect but to fully remove the TomTom device from your phone's Bluetooth settings and delete it from the TomTom MySports app if prompted. Then re-pair from scratch through the app. The watch must be charged above 20% before initiating a new pairing or the BLE stack may not initialise correctly.