Diy Dc Power Measurement Module for Arduino

In this project we will see how to make dc power measurement module using Arduino

for measure dc power we need to measure dc voltage and dc current.

i use voltage divider for voltage measurement

and shunt resistor for current measurement

by using this configuration we can measure dc voltage up to 55V by arduino

in theory if we connect two load in series the current pass through each load is equal so if we replace one of the load with known resistor we can get voltage across the known resistor that voltage is proportional to the current by ohm's low

i got 0.47 ohm resistor surround me but i measure with multimeter it was 0.5 ohm so take 0.5 as calculation

by calculating parameter i got that this resistor can handle 3A of max current and 1.5v drop so i take this parameter as reference

note that the voltage we got across is drop voltage which results lesser usable voltage for load so try to keep as low shunt resistor as possible

by calculating parameter 1.5 volt is too low for arduino to measure current accurately so we need to amplify voltage to 5v max with linear gain

hear i use lm358 as differential configuration

and by calculating gain of 3 i calculate resistor for opamp

by testing circuit on breadboard i make circuit on prototype pcb board

by connecting circuit to arduino and load this code we get voltahe and current reading on serial terminal