My order of USB power meter arrived a few days ago, but only today I could put it into use by plugging it in between the power supply adapter and my RPI.
The way I test the max power consumed is by creating a small C program to do infinite loop such as:
int main()
{
while (1) {}
}
I executed it in four separate processes (open four terminals, and run the program in each one). This way I could exhaust the whole four cores in the CPU. I also GUI desktop on the machine (LXDE).
Here what is shown by "top":
My USB power meter shows 1.17 WH, meaning in each hour it consumes 2.37 Watt or 0.00237 KWh. If the price per kWh charged by Utility company is 12.01 cent ($0.1201/KWH), in a day I'd pay 0.00237 KWh* $0.1201/KWh * 24 hours = $0.006831288 or about $0.0068 per day. In a month I'd pay about $0.2 minimum.
After I killed all those four infinite loop processes, the wattage did not drop. Instead I saw it climbed to almost 2 Watt-hour. I think over time it probably would drop back to around 2 W (idling time).
The way I test the max power consumed is by creating a small C program to do infinite loop such as:
int main()
{
while (1) {}
}
I executed it in four separate processes (open four terminals, and run the program in each one). This way I could exhaust the whole four cores in the CPU. I also GUI desktop on the machine (LXDE).
Here what is shown by "top":
My USB power meter shows 1.17 WH, meaning in each hour it consumes 2.37 Watt or 0.00237 KWh. If the price per kWh charged by Utility company is 12.01 cent ($0.1201/KWH), in a day I'd pay 0.00237 KWh* $0.1201/KWh * 24 hours = $0.006831288 or about $0.0068 per day. In a month I'd pay about $0.2 minimum.
After I killed all those four infinite loop processes, the wattage did not drop. Instead I saw it climbed to almost 2 Watt-hour. I think over time it probably would drop back to around 2 W (idling time).
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