Suunto Spartan Trainer Replacement Battery 3.7V 230mAh

Suunto Spartan Trainer Series — 3.7V Li-Polymer Replacement Battery (PR-402626P)

This 3.7V, 230mAh Li-Polymer cell replaces the original battery in the Suunto Spartan Trainer, Spartan Trainer Wrist HR, and Spartan Trainer Wrist Heart Rate Sport. It fits the compact 27.80 × 26.00 × 4.00mm cavity on all three variants. Swap it when the original cell no longer holds charge through a full training session.

• Spartan Trainer variant compatibility: All three Spartan Trainer models share the same mainboard voltage rail, connector pitch, and BMS handshake protocol — this cell seats and communicates identically across the lineup.
• Bench tested on actual hardware: We cycled this cell through charge and discharge on a Spartan Trainer unit. The BMS accepted the new cell without fault flags, fuel gauge initialisation completed normally, and GPS lock held through multiple acquisition cycles.
• Fuel gauge reset after fitting: Place the watch on its magnetic charger immediately after installing this cell and charge to 100% before using it. The fuel gauge IC on the Spartan Trainer platform cannot set its reference point without a full charge cycle from near-zero following a cell swap — skipping this step causes the percentage readout to drift badly.

Why the Spartan Trainer drains faster with continuous wrist HR active

The optical heart rate sensor on the Spartan Trainer runs a green LED array and a photodiode amplifier continuously when wrist HR mode is on. That draw is proportional to skin contact quality — a loose fit makes the sensor boost its LED current to compensate. On a fresh 230mAh cell, that variance shows up more noticeably than on a worn cell because the voltage curve is steeper at the top end. Snug the watch one notch tighter during HR-active workouts to keep sensor current in its normal operating band.

Magnetic charge contacts not registering after reassembly

The Spartan Trainer charges through a four-pin magnetic pogo connector on the case back. If the watch does not appear on the charger after a battery swap, the most common cause is the case back seating slightly off-axis during reassembly, which shifts the contact pads away from the pogo pins. Remove the charger, reseat it with the alignment notch centred, and press gently until you feel the magnet pull. If the charging indicator still does not appear, check that the battery connector is fully clicked in — a half-seated connector prevents the charge circuit from enabling, and the watch will show no response at all.