About this replacement
TomTom Start 52 / 4AL51 — 3.7V Li-ion Replacement Battery (VF6F)
This is a 3.7V 1000mAh Li-ion cell replacing the original VF6F battery in the TomTom Start 52 and 4AL51 GPS navigators. It restores power to the unit when the original cell has degraded or stopped holding a charge. Voltage and capacity match the original spec exactly.
- Start 52 and 4AL51 compatibility: Both units run the same 3.7V power rail, use the same connector footprint, and draw current through the same BMS handshake. One cell covers both models without modification.
- Bench tested on actual hardware: We cycled this cell through charge and discharge on the Start 52 platform. The BMS accepted the cell cleanly, reported charge state correctly, and hit the full 3.7V nominal without triggering any protection cutoff.
- Cold-start satellite acquisition after power interruption: After fitting this cell, power the unit fully on outdoors before your first drive. The GPS performs a cold start after any complete power removal — first satellite fix can take 5–10 minutes. Subsequent warm starts drop back under a minute once the almanac is cached.
GPS accuracy reduced at low battery on the Start 52
As the original cell ages and internal resistance climbs, voltage sags under the load of active navigation. Some GPS receivers, including the Start 52, reduce RF receiver sensitivity at low voltage to protect the system. The result is a weaker satellite lock and position drift you wouldn't see on a healthy cell. Fitting a fresh 1000mAh cell restores full receiver headroom and brings the unit back to its normal position accuracy.
Start 52 shuts off without any low-battery warning
The battery indicator on the Start 52 reads percentage against a calibrated discharge curve. When the original cell degrades, its actual capacity no longer matches what the firmware expects — the unit can show 30% remaining and cut out seconds later. This happens because the cell's voltage drops sharply once degradation sets in, crossing the hardware cutoff threshold before the display catches up. Fitting a fresh cell re-aligns the discharge curve and restores normal warning behaviour; charge the new cell to 100% and run a full discharge cycle to let the firmware recalibrate.