Why/how do things still use electricity when they are turned off but plugged in (or just plugged in like a charger not connected to anything)? Where does the electricity go?

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Why/how do things still use electricity when they are turned off but plugged in (or just plugged in like a charger not connected to anything)? Where does the electricity go?

In: Technology
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It depends on the device. Most chargers or small devices these days have a transformer in the plug. This transformer changes the voltage from the larger supply to something more useable. This creates a small amount of heat, and loses efficiency. Every time you change something to something else you lose a little bit. Unless it has an off switch before the transformer, or light, or anything which is physically connected, that little bit of power is lost.

A lot of devices when turned off still have part of their circuitry turned on and drawing power. The classic example was the old CRT TV for quick “turn-on.” Some of them drew more power off than modern TVs do when on.

Devices that use a “wall-wart” and other types of internal power supplies that convert ac current to dc still have electricity flowing through transformers (or the equivalent) when turned “off.”

Runs around in a loop. Electricity can only run if it can form a circuit, in other words a long loop which goes back to where it can from. For most devices, it keeps running in that loop as long as plugged in. It’s still drawing a small amount of power, because those electrons moving around is a use of power.

Engineer here. The short answer is, the electricity turns to heat. Put your hand on a wall wart and it will feel warm. That’s where the standby power is going.

Now, the reason something like a phone charger still consumes electricity even if it’s not charging your phone is because it’s not actually off (unless you unplug it from the socket or use a mechanical switch to physically break the electrical connection to the socket). Any time the charger is plugged in, the circuit remains powered up to monitor the output. That way the power starts flowing the instant the phone gets plugged in.

A modern phone charger doesn’t use much power on standby. Something like 0.1 watts. That’s so little you won’t even be able to feel that the charger is a fraction of a degree hotter than room temperature while on standby. To put that in context, charging a phone takes 10-11W (a hundred times the power of standby)

Some things need to be able to turn by remote control, like TV’s, so they need a little bit of power to keep looking for the ON signal. Chargers don’t have an on-switch, so they need to always have 5V DC available at the USB side for whenever a phone is plugged in. That means the AC to DC converter part of the circuitry needs to be engaged all the time.

The one that takes a lot of power when it is “off” is the DVR or cable box. At least the one I have uses as much power when it is off as when it is on. It just turns off an LED but everything keeps running. It monitors the channel guide information which comes in from the satellite dish all the time, and of course when a show comes on that needs to be recorded, it records it. And when you turn on the TV and DVR, you already have history built up, so you can back up and play video from before you turned on the set.