I fried a mosfet that was on the lighter pcbs last night. I wish I would have remembered what a voltage divider was before I wired it up, but you live and learn. Everything else seems to work just fine. it failed open, so now I just can't shut the power off on the timer. I could add a switch, but I like the mosfet there, so I will wait for another shipment to come from China.

I wired the timer to the lighter as in the pic below. (Actually the black wire was moved to the pad below it before I finished). The brown wire was attached to a resistor and a pin on the arduino so I could keep the gate high on the mosfet. There was a problem with this wire, though, it slightly powered the arduino when everything was off. So, I cut the trace to the mosfet gate which made the voltage too high when I powered it up again. It worked fine to power the arduino until then, though. The battery is unlabeled, but it is about 5v. It looks like a lipo cell to me, but I haven't heard of a 5v lipo.

When I get my mosfets, I think I will try to find someplace to put it on the perf board with a voltage divider as a reminder. I know, that was one of the first things I learned about in my high school electronics class, but that was a long time ago. Maybe I need a refresher, or just to take the whole class again.