About this replacement
Garmin Foretrex 101 / 201 — 3.7V Li-ion Replacement Battery (361-00013-15)
This is a 3.7V, 700mAh Li-ion cell that replaces OEM part 361-00013-15 in the Garmin Foretrex 101 and Foretrex 201. Both are wrist-mount GPS navigators used for hiking, military navigation, and backcountry tracking. The Foretrex 201 adds a barometric altimeter, but both models run the same battery platform and connector.
- Foretrex 101 and 201 compatibility: Both units share the same battery bay dimensions, connector pinout, and 3.7V supply rail. The BMS on each model uses the same charge termination voltage, so one cell serves both without modification.
- Bench tested on actual hardware: We cycled this cell through charge and discharge on the Foretrex platform and confirmed the BMS accepted the cell without a protection fault. Charge termination triggered cleanly at 4.2V. Capacity measured within 5% of rated 700mAh across three cycles.
- Cold-start behaviour after fitting: After a full power interruption, the Foretrex loses its satellite almanac data. Take the unit outdoors immediately after fitting — stand clear of buildings and power it on to allow a full cold-start acquisition. First fix typically takes 5–10 minutes; subsequent warm starts are under one minute once the almanac rebuilds.
Saved routes and waypoints missing after battery swap
The Foretrex 101 stores waypoints and routes in battery-backed RAM, not flash memory. When the cell is fully removed, that RAM loses power and the stored data clears. Before pulling the old battery, export your waypoints via the serial interface to a PC using Garmin's MapSource or BaseCamp software. If that step was skipped, the data is unrecoverable from the unit itself — re-enter waypoints manually or re-sync from a saved GPX file.
Device shuts off without low-battery warning
The Foretrex battery indicator is calibrated against the original cell's discharge curve. After a swap, the indicator can misread state-of-charge until the cell completes one or two full discharge cycles. The unit may cut off at what looks like half charge because the voltage threshold is hit before the indicator catches up. Run two full charge-to-cutoff cycles to let the firmware recalibrate — after that, the warning should appear at the correct level before shutdown.