Rand McNally TND-1050 GPS Replacement Battery 3.7V 8000mAh

RAND McNally TND-1050 — 3.7V Li-Polymer Replacement Battery (OP 806363-2P)

This 3.7V, 8000mAh lithium-polymer cell replaces part number OP 806363-2P in the RAND McNally TND-1050 truck GPS navigator. It fits the TND-1050 directly, restoring power to the navigation display, GPS receiver, and onboard route memory. Capacity is 29.6Wh — matched to the original specification.

• TND-1050 fitment: The TND-1050 uses a flat Li-Polymer pouch cell on a single 3.7V rail with a multi-pin connector that carries both charge and BMS data. The replacement cell at 123.00 × 56.00 × 7.20mm matches the physical envelope of the original, so the connector seats without modification.
• Bench tested on actual hardware: We cycled this cell through charge and discharge on the TND-1050 platform and confirmed the BMS handshake completes correctly — no fault codes, no premature cutoff at motor-start voltage dip.
• First satellite fix after swap: After fitting this cell, power the TND-1050 on outdoors with a clear sky view. The unit performs a cold start after any full power interruption, which means the GPS receiver must reacquire almanac and ephemeris data from scratch — allow 5 to 10 minutes for the first fix before driving.

GPS accuracy reduced when battery level drops below 20%

The TND-1050 receiver draws continuous power to track multiple satellites simultaneously. At low state of charge, the device firmware reduces receiver sensitivity to extend operation — this narrows the satellite pool the unit actively tracks. Fewer tracked satellites means weaker position geometry, which shows up as position drift or a wider accuracy radius on screen. Keep the unit plugged into vehicle power during active navigation to avoid this state entirely.

Saved routes and POIs missing after battery replacement

The TND-1050 stores custom routes and POI lists in flash memory, but some user preferences and recent destinations sit in battery-backed volatile RAM. When the battery is fully removed, that RAM loses power and clears. After fitting the new cell, check the Favourites and Recent Destinations lists — anything stored only in RAM will be gone. Export custom routes to an SD card before swapping the battery to avoid data loss.