TL:DR I hadn’t, and found myself with a totally dead car when I was away from home. The kicker? The 12v in my car was bolted away under a cover in the boot (trunk).

There’s a whole bunch of ways to check the health of a car battery yourself, a quick search will reveal that.

In the UK, there’s also a bunch of garages you can go to for a battery checkup, so if doing this yourself doesn’t sound like your kind of thing, maybe try that route?

For context, my car had shown zero indications of battery issues before this happened, so don’t wait for failure, get it checked out early.