this post was submitted on 25 Dec 2024
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I wonder if my system is good or bad. My server needs 0.1kWh.

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[–] [email protected] 17 points 2 days ago* (last edited 2 days ago) (1 children)

It's the other way around. 0.1 kWh means 0.1 kW times 1 h. So if your device draws 0.1 kW (100 W) of power for an hour, it consumes 0.1 kWh of energy. If your ~~device~~ factory draws 360 000 W for a second, it consumes the same amount of 0.1 kWh of energy.

[–] [email protected] -3 points 2 days ago (2 children)

Thank you for explaining it.

My computer uses 1kwh per hour.

It does not yet make sense to me. It just feels wrong. I understand that you may normalize 4W in 15 minutes to 16Wh because it would use 16W per hour if it would run that long.

Why can't you simply assume that I mean 1kWh per hour when I say 1kWh? And not 1kWh per 15 minutes.

[–] [email protected] 6 points 2 days ago* (last edited 2 days ago)

A watt is 1 Joule per Second (1 J/s). E.g. Every second, your device draws 1 Joule of energy. This energy over time is called "Power" and is a rate of energy transfer.

A watt-hour is (1 J/s) * (1 hr)

This can be rewritten as (3600 J/hr) * (1 hr). The "per hour" and "hour" cancel themselves out which makes 1 watt-hour equal to 3600 Joules.

1 kWh is 3,600 kJ or 3.6 MJ

[–] [email protected] 15 points 2 days ago* (last edited 2 days ago) (1 children)

kWh is a unit of power consumed. It doesn't say anything about time and you can't assume any time period. That wouldn't make any sense. If you want to say how much power a device consumes, just state how many watts (W) it draws.

[–] [email protected] 4 points 2 days ago