A trip to the dark side?

In an (ICE) car you have a small nominal 12VDC. Maximum power is reached when the load equals the battery internal resistance (possibly at cranking), so the voltage there is 6VDC. But then there is the charging current plus the regulation required for the F-V converter known as the alternator. Therefore your sensors and comparators have a hard time of it, but they expect you to do fantastic things.

I learned the hard way through making plug in temperature controls for plating lines, and the demands for process chemicals were often +/- 1.5C. If the installation electrician did not comprehend cable power losses, I'd end up the other end of the country trying to combat relay chatter and subsequent burn-out.