I wonder if my system is good or bad. My server needs 0.1kWh.
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kWh is a unit of energy, not power
I was really confused by that and that the decided units weren’t just in W (0.1 kW is pretty weird even)
Wh shouldn’t even exist tbh, we should use Joules, less confusing
At least in the US, the electric company charges in kWh, computer parts are advertised in terms of watts, and batteries tend to be in amp hours, which is easy to convert to watt hours.
Joules just overcomplicates things.
Wow, the US education system must be improved. 1J is 3600Wh. That’s literraly the same thing, but the name is less confusing because people tend to confuse W and Wh
Wow, the US education system must be improved.
I pay my electric bill by the kWh too, and I don’t live in the US. When it comes to household and EV energy consumption, kWh is the unit of choice.
1J is 3600Wh.
No, if you’re going to lecture people on this, at least be right about facts. 1W is 1J/s. So multiply by an hour and you get 1Wh = 3600J
That’s literraly the same thing,
It’s not literally the same thing. The two units are linearly proportional to each other, but they’re not the same. If they were the same, then this discussion would be rather silly.
but the name is less confusing because people tend to confuse W and Wh
Finally, something I can agree with. But that’s only because physics is so undervalued in most educational systems.
Do you regularly divide/multiply by 3600? That’s not something I typically do in my head, and there’s no reason to do it when everything is denominated in watts. What exactly is the benefit?
I did a physics degree and am comfortable with Joules, but in the context of electricity bills, kWh makes more sense.
All appliances are advertised in terms of their Watt power draw, so estimating their daily impact on my bill is as simple as multiplying their kW draw by the number of hours in a day I expect to run the thing (multiplied by the cost per kWh by the utility company of course).
Watt hours makes sense to me. A watt hour is just a watt draw that runs for an hour, it’s right in the name.
Maybe you’ve just whooooshed me or something, I’ve never looked into Joules or why they’re better/worse.
Joules (J) are the official unit of energy. 1W=1J/s. That means 1Wh=3600J or that 1J is kinda like “1 Watt second”. You’re right that Wh is easier since everything is rated in Watts and it would be insane to measure energy consumption by seconds. Imagine getting your electric bill and it says you’ve used 3,157,200,000J.
3,157,200,000J
Or just 3.1572GJ.
Which apparently is how this Canadian natural gas company bills its customers: https://www.fortisbc.com/about-us/facilities-operations-and-energy-information/how-gas-is-measured
Thanks for the explainer, that makes a lot of sense.
Wasn’t it stated for the usage during November? 60kWh for november. Seems logic to me.
Edit: forget it, he’s saying his server needs 0.1kWh which is bonkers ofc
Only one person here has posted its usage for November. The OP has not talked about November or any timeframe.
My home rack draws around 3.5kW steady-state, but it also has more than 200 spinning disks
What are you hosting?
Do you mean 0.1kWh per hour, so 0.1kW or 100W?
My N100 server needs about 11W.
The N100 is such a little powerhouse and I’m sad they haven’t managed to produce anything better. All of the “upgrades” are either just not enough of an upgrade for the money, it just more power hungry.
To my understanding 0.1kWh means 0.1 kW per hour.
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
devicefactory draws 360 000 W for a second, it consumes the same amount of 0.1 kWh of energy.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.
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.
Thanks!
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
0.1kWh per hour can be written as 0.1kWh/h, which is the same as 0.1kW.
Thanks. Hence, in the future I can say that it uses 0.1kW?
If this was over an hour, yes. Though you’d typically state it as 100W ;)
Yes. Or 100W.
I think at max 200w? I also run a pi with a couple of apps on a pi 3 that sips power.
It’s a legitimate issue because it’s 50+ cents per killowat hour where I live so power is very expensive…
that’s insane, i pay like 5¢ a KWh
Holy shit. I’m paying less than 10c per kwh even in the “high usage” tier.
I wish that was ours…
That seems really high, I think power where I live is about 12-14 cents per kilowatt hour. What makes it so expenses where you live?
0.50 $/kWh is a normal price in Europe now
Mostly just that they can. https://www.pge.com/assets/pge/docs/account/rate-plans/residential-electric-rate-plan-pricing.pdf
Take a look, this is the old pricing. They just voted to up it again.
There’s legislation that is moving along to charge people with solar because…idk.
They’re charging for solar because PGE is a greedy fuck.
Yes. There was talk locally for local government to take control of the power but it’s just talk…
It gets over 110 where I live in the summer…so air conditioning can make it very expensive.
Wait this is in the US? How, this is even more expensive than Hawaii, and they have obvious reasons for power to be more expensive there
Yep. And they are talking about a couple more price hikes next year. Significant ones.
PGE serves Northern California. They keep raising rates like 10-15% each year to cover their losses after all the wildfires a couple years ago and because of the greed.
Take note, folks. Watch this trend spread.
Damn, I wish ours was that cheap. We’re roughly $.30/kwh, mostly because our local poco is a reseller of SCE and we’re in a rural area.
You might have your units confused.
0.1kWh over how much time? Per day? Per hour? Per week?
Watthours refer to total power used to do something, from a starting point to an ending point. It makes no sense to say that a device needs a certain amount of Wh, unless you’re talking about something like charging a battery to full.
Power being used by a device, (like a computer) is just watts.
Think of the difference between speed and distance. Watts is how fast power is being used, watt-hours is how much has been used, or will be used.
If you have a 500 watt PC, for example, it uses 500Wh, per hour. Or 12kWh in a day.
I forgive 'em cuz watt hours are a disgusting unit in general
idea what unit speed change in position over time meters per second m/s acceleration change in speed over time meters per second, per second m/s/s=m/s² force acceleration applied to each of unit of mass kg * m/s² work acceleration applied along a distance, which transfers energy kg * m/s² * m = kg * m²/s² power work over time kg * m² / s³ energy expenditure power level during units of time (kg * m² / s³) * s = kg * m²/s² Power over time, × time, is just power! kWh are just joules (J) with extra steps! Screw kWh, I will die on this hill!!! Raaah
Could be worse, could be BTU. And some people still use tons (of heating/cooling).
Power over time could be interpreted as power/time. Power x time isn’t power, it’s energy (=== work). But otherwise I’m with you. Joules or gtfo.
Whoops, typo! Fixed c:
If you have a 500 watt PC, for example, it uses 500Wh, per hour. Or 12kWh in a day.
A maximum of 500 watts. Fortunately your PC doesn’t actually max out your PSU or your system would crash.
kWh is the stupidest unit ever. kWh = 1000J/s * 6060s = 3.610^6J so 0.1kWh = 360kJ
17W for an N100 system with 4 HDD’s
That’s pretty low with 4 HDD’s. One of my servers use 30 watts. Half of that is from the 2 HDD’s in it.
@meldrik @qaz I’ve got a bunch of older, smaller drives, and as they fail I’m slowly transitioning to much more efficient (and larger) HGST helium drives. I don’t have measurements, but anecdotally a dual-drive USB dock with crappy 1.5A power adapter (so 18W) couldn’t handle spinning up two older drives but could handle two HGST drives.
Which HDDs? That’s really good.
Seagate Ironwolf “ST4000VN006”
I do have some issues with read speeds but that’s probably networking related or due to using RAID5.
My whole setup including 2 PIs and one fully speced out AM4 system with 100TB of drives a Intel Arc and 4x 32gb ecc ram uses between 280W - 420W I live in Germany and pay 25ct per KWh and my whole apartment uses 600w at any given time and approximately 15kwh per day 😭
My server rack has
- 3x Dell R730
- 1x Dell R720
- 2x Cisco Catalyst 3750x (IP Routing license)
- 2x Netgear M4300-12x12f
- 1x Unifi USW-48-Pro
- 1x USW-Agg
- 3x Framework 11th Gen (future cluster)
- 1x Protectli FE4B
All together that draws… 0.1 kWh… in 0.327s.
In real time terms, measured at the UPS, I have a running stable state load of 900-1100w depending on what I have at load. I call it my computationally efficient space heater because it generates more heat than is required for my apartment in winter except for the coldest of days. It has a dedicated 120v 15A circuit
Good lord, how much does electricity cost where you are? Combined with the air conditioning to keep the space livable, that would be prohibitively expensive for me
It’s always wild reading the power draw people wrote here.
I knew it was because this is a US & Europe centric site and many people from homelabs actually run Enterprise size rigs, but my 4 member household run on 2kW for the entire house lol and 75℅ of that is just A/C we use at night.
My household of 7 averages 900 watts year-round.
Yeah it’s a bit of a chonk. I don’t remember the exact itemization on the power bill and I don’t have one in front of me.
Around 18-20 Watts on idle. It can go up to about 40 W at 100% load.
I have a Intel N100, I’m really happy about performance per watt, to be honest.
Between 50W (idle) and 140W (max load). Most of the time it is about 60W.
So about 1.5kWh per day, or 45kWh per month. I pay 0,22€ per kWh (France, 100% renewable energy) so about 9-10€ per month.
Are you including nuclear power in renewable or is that a particular provider who claims net 100% renewable?
Net 100% renewable, no nuclear. I can even choose where it comes from (in my case, a wind farm in northwest France). Of course, not all of my electricity, but I have the guaranty that renewable energy bounds equivalent to my consumption will be bought from there, so it is basically the same.
Thanks. I buy Vattenfall but make net 2/3rds of my own power via rooftop solar.
Idles at around 24W. It’s amazing that your server only needs .1kWh once and keeps on working. You should get some physicists to take a look at it, you might just have found perpetual motion.
.1kWh is 100Wh
I ate sushi today.
This is a factual but irrelevant statement
Good point. Now it does make sense. I know the secret to the perpetual motion machine now.
My server uses about 6-7 kWh a day, but its a dual CPU Xeon running quite a few dockers. Probably the thing that keeps it busiest is being a file server for our family and a Plex server for my extended family (So a lot of the CPU usage is likely transcodes).
80-110W
I use unraid with 5950x and it wouldn’t stop crashing until I disabled c states
So that plus 18 hdds and 2 ssds it sits at 200watts 24/7
the boxes i have running 24/7 use about 20w max each, and about half that at idle or ‘normal’ loads.
