A while ago I was wondering why the start/stop stopped activating in my car, I thought the car actually had enough of the system itself!
Cut to the other week I went out to the car and it wouldn't start, instantly realised it was the battery as the dash clock was showing 00:00. Jumped it and down to Halfords to get a battery health check and it confirmed it was a dead battery.
Lifted a Yuasa EFB battery, and fired it in (Halfords want £50 to fit a battery!?!) 10 minutes later all done, got away without having to code it in.