These instructions apply to the Infiniti Q30 (H15) 2015-2019.
For other models, please choose your vehicle here.
Disconnecting the 12 V battery on your Infiniti Q30 (H15, 2015–2019) is a job most owners can manage with one spanner and a bit of care. You might be fitting a fresh battery after some slow, reluctant starts, isolating the electrics before the car sits unused for a while, or making things safe before you work near the airbags, the pretensioners or the wiring. Done in the right order the Q30 relearns cleanly — the engine and transmission controllers resettle over the first few drives, and the only things you actively put back are the clock, the radio, the windows and the tyre-pressure system.
Where the 12 V Battery Is
The 12 V battery on the Q30 sits in the engine compartment, under a cover — the car shares the Mercedes A-class platform, so the layout will look familiar if you have worked on one of those. Open the bonnet, release the cover, and you will see the battery with two heavy cables clamped to posts on top. Identify the terminals before you touch anything: the negative (−) post is marked or capped in black, the positive (+) post in red and usually under a plastic flap. A hold-down clamp keeps the battery secure — leave that in place unless you are lifting the battery out to renew it.
Before You Start
- Switch the ignition fully off, take the key well away from the car, and close the doors so the electrics settle.
- Turn off the lights, climate fan, wipers and any accessories, and unplug chargers from the 12 V sockets.
- Note your radio presets now so you can put them straight back.
- Wait a couple of minutes after switch-off for the control modules to power down.
- Have the right spanner ready (the clamp nuts are commonly 10 mm), plus gloves and eye protection.
Disconnecting the Battery
- Confirm the ignition is off and every electrical consumer is switched off.
- Loosen the clamp on the negative (−) terminal first and lift the lead clear of the post, tucking it aside so it cannot spring back.
- Then loosen and remove the positive (+) lead.
- If you are working near the airbags or pretensioners, wait a few minutes after disconnecting so the system fully discharges.
Reconnecting and Re-initialising
- Refit the positive (+) lead first and tighten its clamp.
- Refit the negative (−) lead last and tighten it.
- Check both clamps are firmly seated before switching anything on.
The Q30 then needs a few items put back:
- Power windows — re-initialise the one-touch (auto up/down) function so the windows work fully on a single press again.
- Tyre pressure monitor — re-store the pressures from the vehicle menu, or let the system relearn as you drive.
- Clock and radio — re-enter the time and your preset stations.
- Warning lights — a few dash lights may glow at first and clear after a short drive.
For a plain like-for-like swap there is nothing to code, but the Q30 is a stop/start car, so fit the correct AGM or EFB battery type to match what came out.
If a Warning Light Stays On or the Car Feels Off
- Recheck that both clamps are tight and squarely seated on the posts.
- Take a short drive so the engine and transmission controllers relearn their idle and shift settings.
- Repeat the window one-touch relearn if a window is behaving oddly.
- If stop/start refuses to work at first, a short run to let the battery charge and the system relearn its state often brings it back.
- Rule out a genuinely flat or old battery, and read any stored code before assuming the worst.
Frequently Asked Questions
Where is the battery on an Infiniti Q30?
In the engine compartment, under a cover. The Q30 shares the Mercedes A-class layout, so the position and cover will look familiar if you have worked on that car.
Which terminal do I disconnect first?
Take off the negative (−) terminal first, then the positive. To reconnect, fit the positive (+) first and the negative last so the spanner never bridges a live post to the body.
What needs resetting afterwards?
Re-initialise the one-touch power windows, re-store the tyre pressures from the menu or by driving, and put the clock and radio presets back. A stray dash light usually clears after a short drive.
Does a new battery need coding on the Q30?
A like-for-like swap does not need coding, but because the Q30 has stop/start you should fit the correct AGM or EFB battery type; some cars benefit from a battery-management reset so the system tracks the new battery’s state.
Will disconnecting the battery clear fault codes or the service light?
It can clear some stored codes and volatile memory, but any live fault will log again once running. A mileage or time-based service reminder normally resets through its own menu rather than by pulling the battery.
How long should I wait near the airbags?
Give it a few minutes after disconnecting before working on the airbags or seat-belt pretensioners, so the system fully discharges.
To relearn the windows, see our Q30 power-window guide. If a warning light stays on, decode it on autodtcs.com.
Independent guide — not affiliated with Infiniti. Always follow your official service manual and safety precautions. Read our full disclaimer.