About this replacement
Siemens VAS5052 / A5E00173177 — 10.8V Ni-MH Replacement Battery (PA000393)
This is a 10.8V, 3800mAh Ni-MH replacement battery for Siemens vehicle diagnostic scanners. It fits the VAS5052, A5E00173177/ES01, and A5E00088646/ES04 platforms. OEM part references are PA000393 and F734A0503.
- VAS5052 and A5E00 platform fit: These three models share the same battery bay geometry, connector pinout, and BMS handshake protocol, which is why a single cell pack covers all of them. The 10.8V rail (three series cells) matches the voltage requirement for the onboard processor, display driver, and wireless module simultaneously.
- Bench tested on actual hardware: We ran this pack on a VAS5052 unit and confirmed the BMS completed the full initialisation handshake without fault codes. Charge acceptance was normal across all three cells, and the protection circuit responded correctly to a simulated over-discharge event.
- Vehicle profile storage warning: Export all saved vehicle profiles and session logs before removing the original battery. The VAS5052 stores active session data in RAM backed by the main battery pack — not in non-volatile flash — so a cold swap will erase unsaved records.
Why the VAS5052 screen dims before the battery indicator shows low
The display driver on the VAS5052 draws from the same 10.8V rail as the processor, but its voltage sensitivity threshold is slightly higher. As cell voltage sags under load, the display controller throttles backlight power before the BMS triggers a low-battery warning. This is a hardware characteristic of the platform, not a fault with the replacement cell. If you see dimming during a live data stream, the pack is approaching the lower end of its usable voltage window — reconnect to charger before the session ends.
Scanner refuses to boot after battery swap
A freshly installed Ni-MH pack can sit below the VAS5052's boot voltage threshold if it has been in storage. The scanner's power management requires the cell voltage to clear approximately 10.0V before it will attempt startup. Connect the scanner to its charger for at least 30 minutes before pressing the power button — do not attempt to boot from a flat pack. Once the BMS confirms cell voltage is stable above that threshold, the unit will start normally.