I have a circuit that has a variable draw of current based on how many revolutions of a wheel is made per hour.
Every other revolution of the wheel my circuit logs data. Which draws around 50 milliamps of current.
I've made this little table to break it down:
RPM per one-mph on 27.5 inch wheel = 12.2RPM
Current draw per activation = 50 Milliamps
activation uptime = 10 Milliseconds
Average speed over 1 hour = 20 mph
RPM @ 20mph = 244 RPM
Revolutions per hour = 14640 RPH
Activations per hour (divide by 2 as im only logging every other) = 7320 Activations
Total activation uptime per hour 73.2 Seconds (7320*10/1000)
But now im struggling to see how I convert this value into a meaningful value. Given my circuit is running at 5 volts I know that drawing 50 milliamps is going to mean im using 0.25 watts. Do I then multiply this by 73.2? to figure out how many wattseconds im using?
Also from that can I then work out how many milliamp hours this is? The reason im trying to work this out is so that I can spec a battery. I think im close but im getting a bit confused.