Ok first day into this experiment. Rather than go a purchase a wattage meter(which can run into the hundreds of dollars), I’ve decided to simply take readings manually at the meters.
I created a simple form in a word processor to record the readings and type them into a spreadsheet to do the calculations.
The meter reading form has 7 columns. (You could get away with 4 but I have 2 meters to read)
- Date and Time
- Meter 1 Current Reading
- Meter 2 Current Reading
- Meter 1 Elapsed Time
- Meter 1 Revolutions
- Meter 2 Elapsed Time
- Meter 2 Revolutions
I also have a spot to write down the Meter Constant (I’ll get to that later)
The first three columns are pretty easy fill in the date and then read the meters. I have one of the ones that simply shows the numbers rather than the dials. The next four record the number of times the little disk goes around and how long it took.
The only other data that I’m collecting is the Meter Constant which is a number that is on the front beside the letters Kh. This can be different from meter to meter but once you’re recorded it you don’t have to have it again.
Once I’ve recorded the numbers I then plug them into my spreadsheet.
I record the current time, and reading and get a change or the amount of power used since I last read the meter and I make a running total.
From there I get a bit tricky. I then use the time and revolutions an calculate the RPM of the little disk (I take the revolutions and divide by time in seconds and then multiply by 60. To get the actual watt hours I then multiply the RPM by the Meter Constant and then by 60.
To get how much money I’m using at the time I take the watt hours, divide by 1000 (getting kilowatts) and then multiply by the rate I’m paying per kilowatt hour.
It all sounds a bit complicated so I’ve created a spreadsheet to do the work for me. I’m still getting the kinks out but I’ll post a copy when I’m sure that it’s bug free.