Sony NV-U50 GPS Navigator Replacement Battery 3.7V 950mAh

Sony NV-U50 Series — 3.7V Li-ion Replacement Battery (3-281-790-01)

This 3.7V, 950mAh lithium-ion cell replaces part number 3-281-790-01 in the Sony NV-U50, NV-U50T, NV-U51T, NV-U53, and related portable GPS navigators. It fits the compact automotive navigation units Sony built for in-vehicle turn-by-turn routing. Dimensions are 36.84 × 31.99 × 8.38mm — measure your original if you are unsure which variant you have.

• NV-U50 series fit: These models share the same battery bay footprint, connector pinout, and BMS handshake protocol. The 3-281-790-01 part number spans the full sub-series, so one cell covers NV-U50, NV-U50T, NV-U51T, and NV-U53 without modification.
• Bench tested on actual hardware: We cycled this cell through charge and discharge on GPS hardware and confirmed the BMS communicates charge state correctly to the device. The protection circuit trips cleanly at low-voltage cutoff without hanging the unit in a restart loop.
• First fix after fitting: After installing this cell, power the unit on outdoors before driving. A full power interruption forces a cold GPS start — expect 5 to 10 minutes for the first satellite lock versus under a minute for a warm start. Do this once in open sky and subsequent locks will be fast.

GPS accuracy dropping at low battery on the NV-U50

When the NV-U50 cell voltage falls below roughly 3.5V, the unit begins throttling the GPS receiver to reduce current draw. This lowers receiver sensitivity and can cause position drift or missed turns on the map. The effect is subtle — the device stays on but tracking becomes less precise. Keeping the battery above that threshold, either via USB power or a fresh cell, keeps the receiver running at full sensitivity.

NV-U50 shutting off without any low-battery warning

This happens when the battery indicator is uncalibrated against the new cell's discharge curve. The unit reads remaining charge against the aged original battery's profile, so the voltage threshold that triggers shutdown arrives before the on-screen warning does. Run two or three full charge-discharge cycles through the device to let the firmware recalibrate its voltage-to-percentage mapping. After that, the warning icon will reappear in time before cutoff.