I'm thinking about buying a compressor to inflate my tyres, I use a foot pump at the moment, is the 12v socket always live, or would I need to start the engine for it to work, thanks.

The 12V socket switches off after a set amount of time of the engine being off (or instantly if the battery is low).

1 minute ago, alexp999 said:

The 12V socket switches off after a set amount of time of the engine being off (or instantly if the battery is low).

Thanks, Would that mean I have to start the engine to inflate the tyres

It's probably a good idea to do that anyway as these inflators pull quite a high current, especially as the modern cars are so sensitive to SOC.

You'll find the compressor works better with the engine running. The extra voltage can make quite the difference.

Just need ignition on.  But the inflator plus all modules awake with ignition on will drain the battery.

Thanks for your help, might just stick with the trusty old foot pump.🙂

My goodness, last time I used a foot pump was the 1970s LOL You are really overthinking this. Just plug your compressor into your 12v socket, turn on the engine & let it idle, and pump your tires up. I've been doing it like that for decades.

My (cheap Chinese made) compressor is gradually losing efficiency.

A couple of days ago I got so fed up of waiting for the required pressure I gave up with the first tyre. Just wasting fuel.

Instead I decided to stop at a local filling station (Shell, nice modern machine, £1 for up to 7 minutes).

Have occasionally found ones that are free to use but of course there's no point in making a special trip.

13 minutes ago, StephenFord said:

I've been doing it like that for decades.

...but you're a very technical sort of guy, always at the forefront of the very latest technology 🤣

7 minutes ago, unofix said:

...but you're a very technical sort of guy, always at the forefront of the very latest technology 🤣

One of the most useful 'car gadgets' I ever got. Set the pressure on the gauge to what you want, switch on, and leave it till it stops...

These are super quick from flat.  Around 3 minutes from 5psi to 34psi.  After a flat on queens funeral, my last compressor giving up, nobody available to come out and help me, I purchased some of the patches for filling holes in tyres and one of these.  Run engine when using though or it'll flatten battery.

https://www.ringautomotive.com/en/product/RTC1000