Rand McNally TND-730 Replacement Battery 3.7V 1600mAh

Rand McNally TND-730 / TND-720 — 3.7V Li-Polymer Replacement Battery (EU074160P)

This is a 3.7V, 1600mAh Li-Polymer cell built to the EU074160P specification. It fits the Rand McNally TND-730 and TND-720 GPS truck navigators. Voltage and connector match the original exactly, so the device powers on without modification.

• TND-730 and TND-720 compatibility: Both units share the same battery bay dimensions, connector pinout, and 3.7V supply rail. One cell fits both. The BMS logic in each device reads the same charge termination signal, so charge cycles complete normally on either model.
• Bench tested on actual hardware: We ran this cell through full charge and discharge cycles on the TND platform. The BMS accepted the cell without fault codes, charge termination triggered at the correct upper voltage, and low-battery cutoff engaged at the expected threshold — no premature shutdowns.
• Cold-start satellite acquisition after swap: After fitting this cell, power the unit on outdoors and let it run until it acquires a full satellite fix before driving. GPS navigators perform a cold start after any complete power interruption — the almanac and ephemeris data stored in RAM is cleared, so the first fix can take 5–10 minutes outdoors with a clear sky view.

Why the TND-730 shuts off without a low-battery warning

The TND-730 uses a voltage-threshold system to trigger its battery indicator. As an original cell ages, its actual capacity drops while the device's shutdown threshold stays fixed. The fuel gauge reads the voltage curve, not true capacity, so the device can jump from showing two bars to cutting off — skipping the warning stage entirely. After fitting a new cell, run two or three full charge and discharge cycles to let the device recalibrate its voltage-to-capacity mapping and restore accurate indicator behaviour.

Saved routes and POIs missing after battery replacement

Some user data on the TND-730 — including saved routes and custom POIs — is held in battery-backed RAM. When the battery is fully removed, that RAM loses power and the stored data is cleared. This is normal behaviour and not a fault with the replacement cell. Before swapping the battery, export any saved routes via the Rand McNally Dock software on a PC, then re-import them after the new cell is fitted and the device has booted fully.