Quick answer

If a G9 will not unlock or start, a depleted low-voltage battery is one possible cause. The handbook says the traction battery normally charges it, but this can stop when traction-battery charge is low. Use the G9 instructions only: its terminal access differs from the G6 and X9.

Before you start

Rule out an ordinary key or app connection problem before opening the front compartment. Stop immediately after collision damage, flooding, smoke, unusual heat, a chemical smell or visible orange-cable damage.

  • Bring the key fob or NFC card to the car.
  • Note the last known traction-battery percentage.
  • Check for any screen, lamp, handle or app response.
  • Open the official G9 handbook at the Jump start pages.

What to do

Before you start, read the complete sequence. Follow these steps in order and stop if the vehicle shows a stronger warning than the one described here.

  1. Try one normal unlock and one normal start attempt. Repeated wake attempts can further reduce the low-voltage supply.
  2. If the vehicle remains dead, follow the G9 handbook to open the front compartment, remove its access cover and expose the 12 V positive-post trim.
  3. Use a matching external 12 V supply. Connect only to the marked G9 points, in the exact polarity and order printed by XPENG.
  4. Follow the documented emergency-off, key-present, brake and gear sequence. Complete the restart within the auxiliary supply’s stated operating window.
  5. After a successful start, remove the cables in reverse order, refit the covers and arrange a low-voltage-system check.

Expected result

You should expect the following result when the documented route is successful: The cluster or centre screen wakes and the car reaches a start-ready state. Recovery is not proof the battery is healthy; a vehicle that becomes unresponsive again needs professional testing and charging-system diagnosis.

If it still does not work

Do not keep reconnecting or substitute a charger if the handbook route does not restore the vehicle. Tell roadside assistance the exact model, whether screens lit after connection, the last traction-battery charge and any warning shown before shutdown.

Safety and model boundary

Incorrect cables or polarity can cause explosion or injury. Do not touch high-voltage components or allow flames/static near a battery. The 2025 English G9 handbook may vary from later or market-specific vehicles, so terminal labels in the car take priority.

Official handbook evidence

XPENG G9 2025 User Manual, PDF pages 336–338 (printed pages 338–340), “Jump start”.

What to record before asking for help

Write down the model, model year, current XOS version and the time the problem occurred. Add the exact display wording, the last action that worked and the outcome of each safe check above. For charging issues include the charger type and its indicator; for access issues include the key method used. Do not include a VIN, registration, account password, PIN or verification code in a public post.

Why this matters: menu names, hardware and behaviour can change with market, model year and XOS version. Record the exact wording shown by the car before contacting support. That gives a service adviser a reproducible symptom instead of a general description.