Let’s say I have a computer plugged in, or a microwave, or phone charger plugged in. Isn’t the point of a device being off is that it’s not supposed to be using electricity? How much watts of power am I looking at that’s being consumed per hour?
Where does this apply and where does it not? Shouldn’t I try to unplug everything as much as possible to save money?
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A small amount of power is needed to keep indicator lights, clocks running, and to be ready for a load at any time.
Although even a laptop charger that draws 0.1 Watts in idle still only comes about to 10 cents a year in addition electricity costs, which is basically inconsequential
My PC monitor has a little red light which remains on even when my PC and monitor are “off”. This is a clear and observable example of how something which is powered off can still use electricity.
A less obvious example is something like an alarm clock. Even if you turn it off, when you turn it back on you will realize that it has accurately been able to keep time during the period in which it was powered off. Electricity is required in order for this to work.
As for kWh, I don’t have an exact answer because it varies, but I read that at most 10% of your energy bill comes from this “phantom energy.”
If you plug a *charger* into the wall, it will automatically draw power. There’s a circuit to modify wall power to charger power. Steps down. Which releases heat. Even if your phone isn’t attached to the other end.
Any device that has a single step power button, like volume keys on your phone, will always consume power to a degree.
Any device with a 2 step power button, one that is visibly capable of being pressed in and staying that way until pressing again, or any physical switch, should nearly cease all power draw.
Single step uses more power than 2 step. Both still use tiny amounts of power when turned off.
Large devices, like your air conditioner, use relays to physically disconnect the power when turned off. You can hear a slap sound just as it powers up. That sound is the crackle of power and the slamming of the contacts being pulled together magnetically.
There’s two issues:
1. Even when a lot of appliances are “off” they actually still have part of the system running to detect when you call for them to start back up.
2. Most electronics run on low voltage DC so they have a power supply with a transformer. There are losses in the transformer even when there’s no load on it.
Some electronics just have a standby mode. In the case of the microwave it needs some power to display the time. Others will check for updates in the background, monitor statuses, stay charged to reduce power on time, and be ready to respond to inputs.
For computerized electronics they all have a power circuit that converts the higher AC wall power to a much lower DC power. This is what is inside the power brick of a phone charger. This conversion circuit is a complete circuit that will always consume some power just due to the nature of the circuit setup.
The power conversion circuit consists of a transformer, which can step voltages up or down. The transformer has a wire that comes in from the hot, coils around a magnetic core of some sort, and goes out to the neutral. The other side of the magnetic core will have a similar wire setup that will have more or less wire coiled around. Since the input is just a coil of wire, it works as a complete circuit and allows electricity to flow through it, consuming some power even though nothing is plugged in on the other side.
This was a bigger problem on old power bricks as they could use a couple watts of power even though nothing was being powered by them.
Modern/good quality power bricks are smart enough to shunt this flow when nothing is plugged into the brick to use the power, but they still need some power to monitor things so it can turn things back on to charge once it’s plugged in. This monitoring is usually a fraction of a watt though and barely noticeable compared to the old or cheap bricks.
some of them have boards that enter standby when you power the device off so theyre always “awake” to do their job
A lot of devices (I’m not talking about chargers but more like tv, computer, game console) don’t really turn off. They just sleep and may even have some part of it running slowly to wake the device up. They still use way less power than when turn on but it isn’t near zero.
The power button doesn’t turn off power. It is just a signal to the device to power on or to go to sleep.
Some devices may wake them up automatically from time to time (you damn windows update!!) for update. That a good example of devices in sleep.
Computers, for example, may still be connected to ethernet in low speed. Because it is a way to turn them on. Same as USB devices (keyboard and mouse).
One reason to not fully shut them down is so they can turn on faster. If they don’t shutdown they don’t have to reload everything. It is already loaded.
Manufacturers don’t care about your electric bills, they just care about the cost on their side.
One silly example is from a YouTuber EEVBlog that makes the math about a silly smoke alarm. Upgrading a component to a more efficient one (for like 0.25$ more (don’t quote me on that)) could shut down a power station because because of the tiny energy saved on a full country scale.
Here in UK we have switches on plugs to switch them of at the wall. Saves having to unplug/plug back in everything which is handy. Until you switch kettle on in morning for a cuppa and go get ready for work only to poor your self a cold tea when you’ve forgotten switch it back on!
Edit: Little typo, switches are on the wall socket themselves not the plug.
If it’s using electronic components it’ll have a tiny draw in standby. If it’s purely electrical (kettle, toaster, most power showers etc) then it won’t draw any current at all when not in use.
A friend turns her shower off when it’s not in use. The cost of running the tiny red light is way less than the cost of replacing the switch when it eventually wears out.
Back when power supplies used transformers, they could use a chunk of current when not in use. Now everything uses switch mode power supplies, the current drain is tiny. Unfortunately, idiot journalists who write stupid articles saying you’re wasting hundreds a year with your TV on standby don’t understand the difference.
During the middle of the night when everyone is asleep and the AC isn’t running my house uses .5kw per hour, thats with countless things plugged in on standby, phones charging, my fridge, nightlight for my kid. unplugging everything that isn’t in use won’t save you any noticeable amount of money off of your bill and just be more of a pain in the ass to keep plugging everything back in when you need it.
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