Launch X431 Diagnostic Scanner Replacement Battery AHB574160P 3.7V 1600mAh

Launch X431 / X431 Diagun — 3.7V Li-Polymer Replacement Battery (AHB574160P)

This is a 3.7V 1600mAh lithium-polymer battery for the Launch X431 and X431 Diagun handheld automotive diagnostic scanners. It replaces part number AHB574160P and restores power to the unit when the original cell has degraded. Mechanics use these scanners for live OBD fault code reads, system tests, and vehicle data access on the workshop floor.

• X431 and X431 Diagun compatibility: Both models run the same 3.7V power rail, use the same AHB574160P cell format, and share the same BMS handshake protocol — the replacement cell trips the same charge and discharge thresholds as the original.
• Bench tested on actual hardware: We cycled this cell through charge and load sequences on the X431 platform. The BMS accepted the cell without error flags, held discharge cutoff at the correct low-voltage threshold, and passed charge termination cleanly at full capacity.
• Vehicle data export before swap: The X431 stores saved vehicle profiles in RAM backed by the main battery. Remove the battery without exporting first and those profiles are gone. Use the scanner's data export function to save all stored vehicle records to a PC or SD card before pulling the old cell.

Why the X431 won't boot after a battery swap

A fresh lithium-polymer cell ships at storage voltage — typically around 3.6V to 3.8V — which can sit below the X431's minimum boot threshold if the cell has self-discharged during transit. The scanner's firmware checks cell voltage before allowing the boot sequence to proceed, and a marginal reading at startup will stall the unit at a blank screen. Plug the scanner into its charger for at least 20 minutes before attempting to power on. Once the cell climbs above approximately 3.85V, the boot sequence completes normally.

Wireless connection dropping mid-diagnostic session

The X431's Bluetooth or Wi-Fi module draws a short current spike when transmitting data bursts to a vehicle ECU. On a degraded battery with high internal resistance, that spike causes a brief voltage sag that the wireless subsystem reads as an undervoltage event, dropping the link. The symptom looks like an intermittent connection fault but the real cause is the battery cell, not the vehicle or the antenna. If sessions drop consistently at the same point in a scan cycle, check cell voltage under load — a healthy cell should hold above 3.5V during active transmission.