Xiaomi 70mai HMC1430 Replacement Battery 3.7V 650mAh

Xiaomi 70mai Dash Cam Pro — 3.7V Li-ion Replacement Battery (HMC1430)

This is a 3.7V 650mAh Li-ion replacement for the internal battery in the Xiaomi 70mai dash cam. It fits the 70mai Dash Cam Pro, restoring the camera's ability to power on, record, and run parking mode without constant external power. The OEM part number is HMC1430.

• 70mai internal cell fit: The 70mai uses a small sealed internal cell rather than a removable pack. This cell handles startup bursts when the engine turns over and sustains the parking mode recording circuit when the vehicle is off. The HMC1430 cell matches the original connector, dimensions (45.50 × 14.50 × 14.50mm), and voltage rail so the BMS handshake completes correctly on first boot.
• Bench tested on actual hardware: We cycled this cell through simulated ignition-on and parking mode draw sequences. The BMS held stable at 3.7V nominal, cutoff triggered cleanly at low-voltage threshold, and charge acceptance from USB was consistent across multiple cycles.
• Parking mode calibration after install: After fitting a new cell, complete one full drive charge cycle before relying on parking mode. The 70mai's capacitor management system calibrates parking mode duration against the new cell — skipping this step can cause premature parking mode cutoff that clears up after a few drive cycles.

Footage corrupt or cut short after parking mode session

When the internal cell is degraded, voltage sags under the sustained parking mode recording draw before the camera finishes writing the file. The dashcam loses power mid-write and the last clip is either corrupt or missing entirely. A fresh cell at full 3.7V nominal holds the voltage rail steady through the write cycle. If corruption persists after replacement, check that the microSD card is Class 10 or UHS-I rated — a slow card causes the same write-fail symptom independently of battery condition.

Internal battery warm after a long parking mode session

The 70mai housing traps heat, especially in a car parked in direct sun. A small 650mAh cell sustaining continuous recording draw in a sealed enclosure will run noticeably warm — this is expected within limits. If the cell feels hot to the touch rather than warm, the parking mode sensitivity setting may be triggering too frequently, keeping the camera recording almost continuously. Drop the motion sensitivity one level in the 70mai app and recheck after the next parking session. Normal operating temperature for this cell is up to 45°C.