About this replacement
Garmin Dash Cam 20 / Nuvi 3400 Series — 3.7V Li-Polymer Replacement Battery (361-00046-00)
This 3.7V, 1000mAh Li-Polymer cell replaces the original battery in the Garmin Dash Cam 20 and Nuvi 3400, 3450, and 3450LM. It restores onboard power for video recording, GPS reception, and route tracking. Dimensions are 56.84 × 47.01 × 3.18mm — measure your existing cell before fitting to confirm the match.
- Dash Cam 20 and Nuvi 3400 series compatibility: These models share the same 361-00046-00 cell format, voltage rail, and connector pinout. The BMS in each device accepts the same charge profile, so one cell covers the full group without modification.
- Bench tested on actual hardware: We cycled this cell through charge and discharge on a Nuvi 3450. The BMS accepted the cell without fault flags, charge termination triggered correctly at 4.2V, and the protection circuit tripped cleanly at the low-voltage cutoff threshold.
- Cold-start satellite acquisition after fitting: After a full power interruption, the GPS receiver loses its ephemeris data and must perform a cold start. Take the unit outdoors and power it on — first satellite fix typically takes 5 to 10 minutes. Subsequent warm starts resolve in under a minute once the almanac is rebuilt.
Why the Nuvi 3450 shuts off without a low-battery warning
The Nuvi 3450 reads battery state through a voltage-threshold lookup, not a fuel gauge IC. When an aged or replacement cell has a steeper-than-expected discharge curve, the device hits its cutoff voltage before the on-screen indicator reaches the final warning bar. The result is an abrupt shutdown that looks like a crash but is actually a low-voltage protection event. After fitting a fresh cell, run two full charge and discharge cycles — the device recalibrates its threshold mapping against the new cell's actual curve.
GPS accuracy drops during active navigation — what's actually happening
Some Garmin units step down receiver sensitivity when battery voltage falls below roughly 3.5V, reducing the number of satellites tracked. With fewer satellites in view, position accuracy degrades and route recalculation becomes less responsive. This is firmware-level power management, not a hardware fault. Keep the unit on USB power during long drives to hold voltage above the sensitivity-reduction threshold and maintain full receiver performance.