About this replacement
Garmin Fleet 670 LM TRUCK — 3.7V Li-ion Replacement Battery (361-00066-51)
This is a 3.7V 1500mAh Li-ion cell built to fit the Garmin Fleet 670 LM TRUCK GPS navigator. It replaces OEM part 361-00066-51 and restores power to the navigation system when the original cell has degraded. Voltage and connector match the original spec exactly.
- Fleet 670 LM TRUCK platform fit: The Fleet 670 LM TRUCK runs a single-cell 3.7V Li-ion architecture with a low-profile connector and BMS handshake tied to the OEM cell spec. This replacement matches that voltage rail and physical footprint — 64.42 × 41.90 × 5.10mm — so the device powers on and communicates normally with the cell from first boot.
- Bench tested on actual hardware: We cycled this cell through charge and discharge on the Fleet 670 platform and confirmed the BMS accepted the cell without fault codes. Capacity held at rated 1500mAh across the test cycles and the device held satellite lock through the full session.
- Cold-start satellite fix after battery swap: After fitting this cell, power the unit on outdoors and let it acquire a satellite fix before driving. The GPS performs a full cold start after any complete power interruption — first fix takes 5 to 10 minutes outdoors. Subsequent warm starts after normal shut-down will be under a minute.
Why the Fleet 670 LM TRUCK shuts off without a low-battery warning
The Fleet 670 reads cell voltage to calculate the battery indicator on screen. After years of use, the original cell's internal resistance rises, causing voltage to sag under the GPS receiver and display load. The device hits its hardware low-voltage cutoff before the software indicator reaches the red zone, so the unit powers off mid-route with no visible warning. Fitting a new cell with lower internal resistance restores the voltage margin and the warning indicator behaves accurately again.
Saved routes and POIs missing after fitting the replacement cell
Some Fleet 670 settings and saved routes are held in battery-backed RAM, which loses state when the cell is fully removed. This is not a fault with the replacement battery — it is a consequence of any complete power interruption to that memory area. Re-enter saved routes and custom POIs manually after the swap. Going forward, use the device's export function to back up routes to the SD card before any battery service.