Rand McNally TND-740C GPS Replacement Battery MLP454094 3.7V

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

This 3.7V 2000mAh Li-Polymer cell replaces the MLP454094 battery in the Rand McNally TND-740C truck GPS navigator. It restores portable power to the unit when the original cell has degraded and can no longer maintain sufficient voltage during active navigation. Dimensions are 86.20 × 39.00 × 4.60mm — measure your original before fitting.

• TND-740C platform fit: The TND-740C uses a flat LiPo pouch cell at this exact footprint and voltage rail. Swapping to a cell outside this voltage window will cause the unit's power management circuit to reject the battery or report incorrect charge state.
• Bench tested on actual hardware: We ran this cell through charge and discharge cycles on the TND-740C and confirmed the BMS accepts the cell without fault flags, reports charge state correctly, and holds the protection circuit within expected cutoff thresholds.
• Cold-start satellite acquisition after swap: After fitting this battery, power the TND-740C on outdoors before driving. The unit performs a cold start after any full power interruption — first satellite fix can take 5–10 minutes. Subsequent warm starts drop to under a minute once almanac data is re-cached.

GPS accuracy reduced at low battery on the TND-740C

When cell voltage drops toward the lower cutoff threshold, the TND-740C reduces power to the GPS receiver to extend operating time. This lowers receiver sensitivity and can cause position drift or loss of fix in areas with marginal signal — tunnels, urban canyons, dense tree cover. The fix is straightforward: charge the battery before use if navigation accuracy matters. A fully charged 3.7V LiPo cell holds around 4.2V at the terminals — that's the operating range where the receiver runs at full sensitivity.

TND-740C shutting off without low-battery warning

After a battery swap, the TND-740C's fuel gauge needs one full charge and discharge cycle to recalibrate its voltage-to-capacity mapping. Until that cycle runs, the unit may display 20–30% charge remaining and cut off without warning — the displayed percentage is wrong, not the battery. Run the device from full charge down to automatic shutoff once, then charge fully again. After that cycle, the on-screen indicator tracks actual cell voltage correctly and low-battery warnings appear at the expected threshold.