Rand McNally TND-740 GPS Replacement Battery 3.7V 2200mAh

Rand McNally TND-740 — 3.7V Li-Polymer Replacement Battery (MLP454094)

This 3.7V, 2200mAh lithium-polymer cell replaces the original MLP454094 battery in the Rand McNally TND-740 trucking GPS navigator. It restores battery-powered operation for in-cab route guidance and waypoint tracking when the unit is disconnected from the vehicle's power outlet. Dimensions are 82.00 × 45.00 × 4.90mm — verify your original cell before fitting.

• TND-740 platform fit: The TND-740 uses a slim LiPo pouch cell on a 3.7V single-cell rail. The MLP454094 footprint is specific to this unit — the connector orientation and cell thickness both matter. Confirm your original part number before ordering.
• Bench tested on actual hardware: We cycled this cell through charge and discharge on the TND-740 platform. The protection circuit handled cutoff at the low-voltage threshold correctly, and the charge controller accepted the cell without fault flags.
• Cold-start calibration after swap: After fitting, power the unit on outdoors and let it acquire a satellite fix before driving. A full cold start after complete power removal takes 5–10 minutes for first lock. Subsequent warm starts drop to under a minute once the almanac data rebuilds.

Why the TND-740 shuts off without warning at low battery

After a replacement, the fuel gauge IC loses its calibration data and no longer accurately tracks state of charge. The battery indicator can show one bar remaining while the cell is already near the 3.0V cutoff threshold. The protection circuit then trips and the unit powers off abruptly — no low-battery warning fires. Run two or three full charge cycles to let the gauge recalibrate against the new cell's actual capacity curve.

GPS accuracy drops noticeably during active turn-by-turn navigation

At low state of charge, some GPS receivers reduce RF front-end sensitivity to conserve power — the TND-740 exhibits this behaviour below roughly 3.3V under load. Fewer satellites are tracked, HDOP rises, and position jumps increase. The fix is straightforward: keep the unit on the vehicle charger during active navigation, or charge the battery to full before a trip where the cable won't be connected. A fully charged cell holds the receiver at full sensitivity throughout the session.