Part of this bigger project, car computer, I wanted sepatate meter for voltage, in case of alternator fault. Idea is simple; voltage divider circuit converts voltage for more suitable level for AtTiny85 that can handle up to 5 volts to ADC (analog to digital converter and Attiny then converts this data and shows it in 7-segment display. Also there is bargraph display to give another perspective, easier to look on-road that charge level is in "green" region, not too much or too low.
Once again, prototyping started at breadboard, and I also made AtTiny programming shield for easier coding sessions, no need to play that much with jumper wires.
There was quite chore to place all stuff in confined area (inline fuse is also coming in final installation):
Another trouble was finding suitable enclosure, but recently bought 52mm dashboard meter casings, and all that was needed was meter panel, solution was 3d-printer. And in the end, it looks quite good in dark too: