Low Car Battery Alert?

So I am thinking of a low car battery alert:

  • Voltmeter display, I’d have it mounted out of sight. Check it if you want, or not.

  • Mount directly to battery

  • SPST Switch to turn it off during long term parking so the very, very minimal drain doesnt kill battery

  • LED that turns on when voltage goes below X (12v, 11v, not sure where to set threshold but that’s not a big deal). Blinking might be distracting (ok, battery is low, plz stop blinking during entire drive). I thought about a speaker but thatd be annoying just a buzzing when like car is parked and low voltage

I assume I’d use like an adafruit trinket or ardunio micro for this ( i think sparkfun has an equivalent thats better but not as cheap and i imagine trinket would be enough for this).

Thanks.

Ok. Go for it…