Disconnect and Reconnect the 12V Battery

Disconnecting the 12 V battery on your NIO ET7 (2022–2024) is something you’ll do before a long storage lay-up, ahead of electrical work or work near the airbags, or to recover the car if the low-voltage side has drained. This is the low-voltage 12 V battery only. The high-voltage drive battery is a separate, sealed system and must never be touched — you only ever handle the 12 V unit here. As on any EV, that 12 V battery still runs the everyday electronics, wakes the car, and powers the lights and controls, so knowing how to take it off and back on safely is worth having. Work in the right order and the car relearns without fuss.

Where the 12 V Battery Is

The 12 V battery is in the front service compartment, under the front lid/cover. Release the front cover to expose it. You’re looking for two clamped terminals: the negative (−) earth/ground lead, usually black, and the positive (+), usually red and often under a cap. Identify both clearly before you reach for a spanner.

High voltage: never touch the orange high-voltage cabling. This procedure is only the 12 V battery.

Getting Ready

• Power the car fully down and make sure it is not in READY — the drive system must be off, not just the screen dark.
• Take the key or phone key away from the car so it doesn’t wake and re-power the electronics.
• Switch off the lights, climate, and anything drawing power.
• Note your personal settings, though most are tied to your NIO account and return when you sign in.
• Wait a couple of minutes for the modules to power down, and have the right spanner, gloves, and eye protection ready.

Find the 12 V Battery First

Disconnecting Safely

1. Power the car fully off and wait a couple of minutes for the systems to power down.
2. Open the front service compartment to reach the battery.
3. Slacken and remove the negative (−) terminal first, then move the cable clear of the post.
4. Only then loosen and lift off the positive (+) terminal.
5. If you’re working near the airbags, wait a few minutes after disconnecting before you begin.

Reconnecting and Re-initialising

Reverse the order: fit the positive (+) first, then the negative (−) last, and tighten both clamps securely. Then a few things need settling:

• Power windows — re-initialise the one-touch/anti-pinch by holding each switch fully up at the top limit and fully down at the bottom.
• Tyre pressure monitor — drive a short distance to re-store the pressures.
• Allow the car a minute to wake fully before driving off.

If Something Isn’t Right Afterwards

• Check both clamps are tight and fully seated — a loose earth is the usual cause of odd electrical behaviour.
• Warning messages often clear after a short drive once the car sees everything working normally.
• If a window won’t auto-close, repeat the hold-at-the-limits relearn.
• If the 12 V side keeps going flat, rule out a genuinely tired battery — fit a like-for-like unit of the correct type and rating.
• If an alert stays on, it has stored a code — look it up on autodtcs.com.

Frequently Asked Questions

Where is the 12 V battery on a NIO ET7?

In the front service compartment, under the front cover — separate from the high-voltage drive battery. Release the front lid to reach it.

Is it safe to disconnect the battery on an EV?

Yes — the 12 V battery is low voltage and owner-safe to handle. Never touch the orange high-voltage cabling; that system is sealed and only for trained technicians.

Which terminal do I disconnect first?

The negative (−) terminal first, and reconnect it last. That removes the ground path before you work on the positive side.

What needs resetting afterwards?

Mainly the one-touch windows and the tyre-pressure monitor. Most personal settings are tied to your NIO account and return when you sign in, and a short drive clears most transient messages.

Does a new 12 V battery need coding?

Fit a like-for-like unit of the correct type and rating. A straightforward like-for-like swap generally needs no special coding, but matching the original battery keeps the electronics settling in normally.

Can I jump-start it instead of disconnecting?

For a flat 12 V battery, the car provides a boost/jump point so you can wake it without pulling the terminals. Disconnecting is only needed for storage or work near the airbags and electrics — and you never jump from the high-voltage system.

To relearn the windows, hold each switch at its upper and lower limits for a moment. If a warning stays on after everything is reconnected, decode it on autodtcs.com.