I want to measure 12v. Car battery with arduino. Three questions:
- Is the R1 and R2 the best values? The car battery can go from +10v. To +15v.
- How and what can I use to save power between the measure reads? Like a transistor to switch on and off or something like.
- Must I add something to protect arduino pin from car battery overvoltage?
I have this:
———————————————— +10v. To 15v. Car battery | | Something here to switch off and save power? | | R1 = 150kOmh | |——————————- to analog arduino pin to read voltage | | R2 = 470kOmh | | ——————————————————- GND negative battery
———————————————— +10v. To 18v. Car battery | | R1 = 36kOmh | |———————————————- to analog arduino pin to read voltage | | | | R2 = 10kOmh 5.1v Zener diode to protect arduino pin | | | | —————————————————————————— GND negative battery and arduino