These instructions apply to the Hyundai i20 Mk3 (BC3) 2020-Present. For other models, please choose your vehicle here.
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Disconnecting the 12 V battery on your Hyundai i20 Mk3 (BC3, 2020–present) — to change it or to safely work on the electrics — is a simple engine-bay job. This guide covers safe disconnection and the items the i20 needs re-teaching afterwards.
Where the Battery Is
The 12 V battery is in the engine bay, under a cover. Even on the 48 V mild-hybrid (mHEV) i20 the main 12 V battery is here — there’s no separate owner battery to find.
Disconnecting
- Make sure the ignition is off and the key/smart key is away from the car.
- Loosen the negative (−, black) terminal first and lift the lead clear.
- If removing the battery, loosen the positive (+, red) next, then the hold-down.
Airbag/pretensioner safety: if you’ll be near airbags or seat-belt pretensioners, wait 3 minutes after disconnecting before continuing.
Reconnecting & Re-teaching
- Reconnect positive (+) first, then negative (−) last; tighten and refit the cover.
- Reset the date/time and check the trip computer.
- Re-initialise the power windows — auto up/down may drop out. See our i20 Mk3 window guide.
Hyundai doesn’t require the new battery to be coded on the i20.
Frequently Asked Questions
Which terminal first on the i20?
Always the negative (−) first, and reconnect it last.
Does it need the battery registered?
No — just fit it and re-teach the windows.
Will I lose my radio?
No — the i20’s audio isn’t code-locked; just reset the clock.
Why won’t auto-up work afterwards?
Cutting power clears the windows’ learned top position; run the quick re-initialise to restore one-touch.
For any warning light that stays on, look up the code on autodtcs.com. To clear the service reminder, see our i20 Mk3 service reset guide.
Disclaimer: The information on this page is provided for general guidance only. Always follow your official service manual and safety precautions when working on your vehicle. We are not responsible for errors, omissions, or any damage resulting from the use of this information.
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