Any stopwatch recommendations? I need one with a long battery

Any with a standard lcd screen can work for years indefinitely

Think about it this way. Your standard Casio terrorist watch uses no more power when it enters its stop watch mode and it lasts for 5+years on a single battery

Go to amazon and get the one with the best reviews under $10

All of them will be quartz crystal based meaning they all will be significantly more accurate than your reaction time

>>1113527
the classic Casio F91W

https://en.wikipedia.org/wiki/Casio_F-91W

i had one in middle/highschool, very reliable, i don't think i ever remember replacing the battery.

Guys, it has to work for 10 hours per day AT MOST. It needs to have a built-in cutoff switch to ensures it cannot function longer than that each day.

OP- sounds like you need to read books on electronics and programming. Also get yourself a 3D printer and a few Arduinos and Raspberry Pi's. You'll figure it out. Post results.

>>1113527
>Your standard Casio terrorist
This. Just get some cheap one from walmart. It'll last years (even if you're "using it" 10+ hours daily) unless you're constantly illuminating the screen all day long or something.

>>1113549
lol

>>1113549
A quartz Crystal oscillates around 262khz in a watch, so all you need to do is measure 9,432,000,000 oscillations, cut off screen and control, then turn control/screen on again again in 13,204,800,000 more oscillations