Disconnect and Reconnect the Battery

Disconnecting the 12 V battery on your Hyundai i10 Mk3 (AC3, 2020–present) — to change it or to safely work on the electrics — is a simple engine-bay job. Owners usually do it when renewing a worn battery, isolating the electrics before wiring or bodywork, laying the car up for storage, or recovering after a flat. Done in the right order the i10 wakes up cleanly and the only thing it really wants back is the windows re-teach; the rest is just resetting your clock and presets. The i10 is a straightforward petrol car with no high-voltage system, so there’s nothing exotic to worry about — it’s a job most owners can do on the driveway with a single spanner in a few minutes.

Where the Battery Is

The 12 V battery is in the engine bay, under a cover. Lift the cover and you’ll see the two terminals: negative (−) on the black lead and positive (+) on the red lead, usually under a protective flap. Identify both before you touch a spanner so there’s no doubt which one you’re loosening.

Before You Begin

• Make sure the ignition is fully off and lights, heater, doors and boot are shut.
• Take the key out (or keep a smart key away from the car) so it can’t re-wake a module mid-job.
• Note your radio presets and clock so they’re quick to restore.
• Wait a minute or two after switching off for the control units to power down.
• Have the right spanner (usually a 10 mm nut), gloves and eye protection ready.

Disconnecting

1. Make sure the ignition is off and the key is out (or a smart key is away from the car).
2. Loosen the negative (−, black) terminal first and lift the lead clear, then secure it so it can’t spring back onto the post.
3. If you’re removing the battery, loosen the positive (+, red) next, then undo the hold-down and lift the battery out.

Airbag/pretensioner safety: if you’ll be near airbags or seat-belt pretensioners, wait 3 minutes after disconnecting before continuing.

Reconnecting & Re-teaching

1. Refit the battery and hold-down, then reconnect positive (+) first and negative (−) last; tighten both and refit the cover.
2. Reset the date/time and check the trip computer.
3. Re-initialise the power windows if auto up/down drops out — see our i10 Mk3 window guide.
4. If the service reminder needs clearing after the work, follow our i10 Mk3 service reset guide.

The i10 doesn’t need a like-for-like 12 V battery coded — fit it, reconnect in order, reset the clock and re-teach the windows.

If a Warning Light Stays On or the Car Feels Off

• Recheck both terminals are clean and properly tight — a loose clamp is the most common cause of trouble after a disconnect.
• Let the car relearn over a gentle 10–15 minute drive; several lights self-clear once systems see normal running.
• If one-touch windows still won’t work, run the window re-initialise again — it’s easy to miss a step.
• If it was hard to start or died again quickly, the battery itself may be flat or worn out.
• Any code that won’t clear on its own can be read and looked up so you know what you’re dealing with.
• Give it a few key cycles — some stored trip and computer data repopulates over the first drive rather than instantly.

Frequently Asked Questions

Where is the 12 V battery on the i10 Mk3?

In the engine bay, under a cover. Lift the cover and you’ll see the black negative and red positive terminals — it’s an ordinary small 12 V battery, easy to reach with a basic spanner.

Which terminal do I disconnect first?

Always the negative (−) first, and reconnect it last. That order stops a slipped spanner bridging the positive post to the bodywork and causing a short.

Will I lose my radio?

No — the i10’s audio isn’t code-locked, so it comes straight back. You’ll just need to reset the clock and re-enter your station presets after reconnecting.

Why won’t auto-up work afterwards?

Cutting power clears the windows’ learned top position, so one-touch and anti-pinch drop out. Run the quick re-initialise from our window guide and full auto up/down comes back.

Does a new battery need registering on the i10?

No — a like-for-like 12 V battery needs no coding or registration. Fit it, reconnect in the right order, reset the clock and re-teach the windows, and you’re done.

Can I jump-start it instead of disconnecting?

If the battery is just flat you can jump-start the i10 from the 12 V terminals rather than pull the battery. But a battery that keeps going flat is worn out, and disconnecting to renew it is the proper fix. After a jump-start, a decent drive lets the alternator put charge back in; if it won’t hold that charge overnight, the battery has reached the end of its life.

For any warning light that stays on after the job, look up the code on autodtcs.com so you know exactly what it’s telling you.