Mio Mivue 338 Dashcam Compatible Battery 3.7V 450mAh TPC402339

Mio MiVue 338 / 366 / 368 / 388 — 3.7V Li-Polymer Replacement Battery (TPC402339)

This 3.7V, 450mAh lithium-polymer cell replaces part number TPC402339 in the Mio MiVue 338 dashcam and its close variants. It fits the MiVue 338, 366, 368, and 388 — compact car dash cameras that use the same internal cell format. Dimensions are 35.30 × 25.50 × 5.60mm, matching the original cell footprint inside the housing.

• MiVue 338 / 366 / 368 / 388 compatibility: These models share the same compact chassis, internal cell bay, and connector layout. The TPC402339 cell slides into each without modification — same voltage rail, same physical envelope, same flex connector orientation.
• Bench tested on actual hardware: We ran this cell through charge and discharge cycles on the MiVue platform. The BMS accepted the cell without error flags, and the dashcam exited boot into normal recording mode without prompting a battery fault screen.
• Parking mode calibration after replacement: After installing a new internal cell, complete one full drive cycle before relying on parking mode. The dashcam's capacitor management needs to calibrate against the new cell before it can accurately gauge how long parking mode will sustain.

Why the MiVue 338 won't start recording on engine start

If the internal battery has dropped below the BMS's minimum threshold — typically around 3.0V on Li-Polymer cells — the dashcam may refuse to boot even when 12V power is present at the USB or hardwire port. The camera draws from the internal cell during the boot sequence before switching to sustained input power. A deeply discharged original cell can block this handoff entirely. Connecting via USB for 15–20 minutes before expecting autonomous start gives the cell enough charge to clear the boot threshold.

Footage missing or corrupted after parking mode sessions

Parking mode writes continuously to the SD card in short looped segments. If the internal battery voltage sags mid-write, the file closes incomplete or the header gets corrupted. This happens most often when the cell is aged and can no longer sustain voltage under the sustained recording draw inside an enclosed, warm cabin. A replacement cell restores stable voltage delivery through the write cycle. Check that the cell reads at least 3.7V under load — anything below 3.5V during active recording is the threshold where file corruption becomes likely.