Hello,
There is something I don’t get about power and energy.
If I got it right, power is expressed in Watts or Joules ans energy is in Watts.hours.
So if I buy à power supply rated at let’s say 700W. Does that mean (assuming, for the sake of the argument 100% efficiency and 100% load) it also consumes 700Wh ? And also that 700W is it’s maximum power output ?
In: 2
Watts is a unit of energy flow. Joules is just a unit of energy. Watt-hours is also a unit of energy, just in a different unit that makes sense for electrical applications that use Watts (like Celsius vs Fahrenheit are both temperature units).
So for your 700W power supply, it is rated to supply 700W continuously to its downstream user. At max, consuming 700W continuously. If you run it for an hour, it will have consumed 700Wh.
But usually, you select your power supply with some error margin, so say your downstream user of the PSU only consumes 350W. The PSU will only consume 350W from the wall, even though it could handle more. If it ran like that for 4 hours, it would have consumed 1400Wh (350W x 4h). So if you had a 1000Wh backup battery, it could run that PSU for a little under 3 hours (1000Wh / 350 W = 2.86 h)
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