TomTom Star 40 GPS Replacement Battery VF3S 3.7V 700mAh

TomTom Star 40 / Star 40 Euro — 3.7V Li-ion Replacement Battery (VF3S)

This is a 3.7V, 700mAh Li-ion cell that fits the TomTom Star 40 and Star 40 Euro portable GPS navigators. It replaces OEM part numbers VF3S and AHA11108003. Swap it in when the original cell no longer holds enough charge to complete a navigation session.

• Star 40 and Star 40 Euro fit: Both variants use the same 3.7V cell with identical connector pinout and physical footprint (36.70 × 36.50 × 5.80mm). The BMS on each unit accepts the same charge termination voltage, so one cell covers both.
• Bench tested on actual hardware: We cycled this cell through charge and discharge on the Star 40 platform and confirmed the BMS reached full charge termination without fault. Discharge cutoff triggered cleanly at the low-voltage threshold before the unit hard-reset.
• First-fix cold start after fitting: After fitting this cell, power the unit on outdoors before driving. A full power interruption clears the GPS receiver's ephemeris data and forces a cold start — first satellite acquisition takes 5–10 minutes outdoors. Subsequent starts drop back under a minute once the almanac rebuilds.

GPS accuracy reduced at low battery on the Star 40

The Star 40's GPS receiver draws the most current of any subsystem in the unit. When cell voltage drops toward the lower threshold, the device scales back receiver sensitivity to stretch remaining charge. You'll notice position jumps, sluggish rerouting, or the blue dot lagging behind your actual position. Plug in via USB or swap the cell before voltage drops below 3.5V to keep the receiver running at full sensitivity.

Star 40 shuts off without warning before the low-battery indicator appears

After fitting a new cell, the fuel gauge on the Star 40 may not reflect the actual charge state until it completes a full calibration cycle. The unit's shutdown threshold can trigger before the on-screen battery icon shows critical. Run one full charge from flat to 100% without interruption — this lets the BMS re-learn the cell's capacity curve and realign the visual indicator with the actual cutoff voltage.