Electronic – Power calculation in kwh over a period of time with a variable current source

currentpowerpower supplyvoltagewatts

I have an experiment running which generates variable current due to a chemical reaction over a period of 8 hours. I sampled the current at each hour with a constant voltage supply of 12V. When i use P= I*V i get the power at that particular reading.

My assumption to calculate a the power consumed during the complete experiment was to plot a graph between the power at each hour and experiment duration. Calculating the area under the plot graph will be power calculated per experiment but not in kwh.

Is my assumption true or is there a mathematical formula that i have to use to calculate the power in kwh.

Best Answer

  • Power is measured in watts (W).
  • Electrical energy is measured in watt-hours (Wh).

Your understanding of P = VI is correct and will be in watts. That gives you the power. Since your interval of measurement is one hour the watt-hours will be the same numerical value.

Assuming the power rises or falls continuously during the experiment (rather than randomly increasing and decreasing) I would use the average power for the interval: \$ P_{n} = \frac {P_{n-1} + P_n}{2} \$ where \$n\$ is the measurement number.