At 06:28 AM 10/15/2012, Jack Cole wrote:
Input power.
W = ((Amperage at Time 1 + Amperage at Time 2) / 2) * ((Voltage at
Time 1 + Voltage at Time 2) / 2) * (Minutes in interval / 60)
You are going to go nuts if you don't keep your units straight, and
don't keep in mind the difference between power and energy.
The forumula you give calculates average power for an interval (Time2
- Time1), then multiplies it by the time in hours, presumable to get
watt-hours, not watts. Watt-hours are a measure of energy.
That's not generally correct, because the energy is the integral of
the power over time, not the product of the average energy and the time.
If the current has no significant AC component, and you measure
voltage and current frequently, you can sum the product in a
spreadsheet. Otherwise it gets really complicated.
In a standard CF experiment, the voltage/current measurements might
be once per minute. Or in more sophisticated experiments, the
measurements might be more frequent than that.
