Navman Spirit S100 Replacement Battery 3.7V 650mAh

Navman Spirit S100 Series — 3.7V Li-ion Replacement Battery (338937010171)

This 3.7V, 650mAh Li-ion cell replaces the original internal battery in the Navman Spirit S100, Spirit S100T, and Spirit S150 portable GPS navigators. It fits the slim battery bay directly and restores power to the GPS receiver, display, and onboard memory. Capacity matches the factory spec at 650mAh (2.41Wh).

• Spirit S100, S100T, and S150 compatibility: All three models share the same battery bay dimensions, connector pinout, and 3.7V supply rail — the cell slots in without modification and the device powers on normally.
• Bench tested on actual hardware: We cycled this cell through charge and discharge on the Spirit S100 platform. The BMS held the cutoff voltage correctly and the unit's low-battery indicator tracked accurately across the full state-of-charge range.
• Cold-start satellite acquisition after fitting: After any full power removal, the GPS receiver loses its ephemeris data and must perform a cold start. Take the unit outdoors and power it on before your first navigation session — first satellite fix takes 5–10 minutes; every subsequent fix after that is under a minute.

GPS accuracy dropping as battery charge falls

Some GPS units reduce receiver sensitivity at low supply voltage to protect the processor from a hard cutoff. On the Spirit S100, this can appear as position drift or a wider accuracy circle before the battery indicator shows critical. A degraded original cell exaggerates this — its internal resistance causes voltage sag under the receiver's draw even when the display reads half-charged. Fitting a fresh cell with stable internal resistance keeps the supply voltage above the threshold where the receiver runs at full sensitivity.

Device shuts off without warning before the low-battery alert appears

The Spirit S100 calibrates its battery indicator against the original cell's discharge curve. An aged cell drops voltage steeply in the final 20% of charge, so the unit hits the hardware cutoff voltage before the software low-battery warning has time to display. This is a calibration mismatch, not a fault with the replacement cell. After fitting this battery, run two full charge-to-discharge cycles to allow the device to re-read the discharge curve — the warning indicator will then appear at the correct point before shutdown.