TomTom Go 400 3.7V Replacement Battery ICP523436 700mAh

TomTom Go 400 4FB40 — 3.7V Li-ion Replacement Battery (ICP523436)

This is a 3.7V, 700mAh Li-ion cell that replaces the original ICP523436 battery in the TomTom Go 400 4.3" Satnav and 4FB40. It fits directly into the GPS housing using the same connector and cell dimensions (36.50 × 36.50 × 5.70mm). When the original cell no longer holds enough charge to run active navigation, this is the direct replacement.

• Go 400 and 4FB40 fitment: Both models use the same ICP523436 cell format, voltage rail, and connector. The BMS handshake is identical across both, so no firmware conflict occurs on first boot after fitting.
• Bench tested on actual hardware: We ran this cell through charge cycles on the Go 400 platform and confirmed the BMS accepted full charge without fault flags. Cutoff voltage held at the correct threshold throughout discharge.
• Cold-start preparation after fitting: After fitting this cell, power the unit on outdoors and let it acquire a satellite fix before your first journey. The GPS performs a full cold start after any complete power interruption — first fix takes 5–10 minutes. Subsequent warm starts drop to under a minute once ephemeris data is cached.

GPS accuracy reduced at low battery on the Go 400

As cell voltage drops toward 3.2V, some TomTom Go units reduce receiver sensitivity to conserve power. This shows up as position drift, late route recalculations, or the blue dot jumping between streets. The GPS chip is still running, but signal processing is throttled. A freshly charged cell returning 3.7V at rest resolves the behaviour immediately.

Go 400 shuts off without warning before the low-battery indicator appears

An aged cell loses capacity unevenly — voltage holds steady until it collapses suddenly under the load of the display and GPS receiver combined. The battery indicator reads one bar, then the unit cuts off before reaching the warning screen. This happens because the indicator is calibrated against a fresh cell's discharge curve, not a degraded one. After fitting a new cell, recalibrate the gauge by running a full charge-to-cutoff cycle before relying on the indicator.