I have a file which contains watt readings for various times throughout the day. A reading is stored roughly every 6 seconds.
206,2012/04/24 00:00:05 400,2012/04/24 00:00:21 300,2012/04/24 00:00:23 90,2012/04/24 00:00:29
I have two methods of working out a total kilowatt-hour figure from the above readings.
I take an average of the watt reading, so
206+400+300+90 = 790 / 4 = 197.5
Then i work out the total range of the file, so 29 - 5 = 24 seconds.
Then i work out the kWh by converting the avg. watts to kW 197.5 / 1000 = 0.1975 Convert the seconds to hours, 24/3600 = 0.006666666 Then 0.1975 * 0.00666666666666667 = 0.00131666 kwh.
The other method i have is to work out the kwH per line and keep a running total:-
I do this by working out how long the first reading lasted by subtracting the second readings time value from the first. We assume the last line lasted 6 seconds as we havent got a reading after it to distinguish its length.
206,2012/04/24 00:00:05 lasted 16 seconds so 206 for 16 seconds = ? kwh 400,2012/04/24 00:00:21 lasted 2 seconds so 400 for 2 seconds = ? kwh 300,2012/04/24 00:00:23 lasted 6 seconds and so on.... 90,2012/04/24 00:00:29 assume last record lasted 6 seconds
I then work out the kwh per line and keep a running total of the kwh reading.
Question is, which is more accurate, and would there be a massive difference in the accuracy of the two methods.