Kia EV6: 12V auxiliary battery drain causing system reset and no-start

The EV6, like other e-GMP platform EVs, uses a small 12V auxiliary battery to power low-voltage systems. This battery is charged by a DC-DC converter from the HV pack. Multiple documented cases exist of the 12V battery failing prematurely — within 2–3 years — causing complete system reset, inability to start, loss of door unlocking, and loss of infotainment. The vehicle may show as fully charged on the HV side but fail to power on. The 12V battery in EV6 early production was identified as undersized for the parasitic load.

• Vehicle fails to power on despite HV battery showing charge
• Complete electrical reset — clock, settings lost
• Door unlocking failure or intermittent central locking
• Warning lights across multiple systems on startup

1. 1

   Test the 12V auxiliary battery voltage and load capacity with a dedicated battery tester.

2. 2

   Check age and replacement history of the 12V battery.

3. 3

   If the vehicle has sat unused for more than 2–3 weeks, check for symptoms of drain.

Parts involved: 12V battery.

≈A$230 to ≈A$550 at independent workshop rates, shown as an approximate guide in Australian dollars. That is for this job on its own, not for the car.

An estimate, converted to Australian dollars, for the repair as normally carried out. What a specific car costs depends on which part has failed and what it damaged on the way — treat this as the floor for a negotiation, not a quote.

• “Has the 12V auxiliary battery been replaced?”
• “Any episodes of the car failing to power on?”
• “Has the vehicle been left unused for extended periods?”

The failure described above is documented in published sources — owner forums, technical service bulletins, recall notices and workshop write-ups — held in our fault database. The inspection instructions and the cost estimate are KickTyres’ own interpretation of them, and it is a starting point for an inspection rather than a manufacturer statement.