Do chargers use power when plugged in but not in use?

Many of us use USB chargers along with standard plug-in adapters to charge up our various devices. Obviously they use power when in use, but what about when they are not being used - do they use power or not?

Help us bust this consumer myth and provide some helpful advice to enter our competition.


If turned on at the power point (in some cars, power points can draw from a battery even when an vehicle is not running if that point is made to draw from the vehicle battery) they do, it may only be a very small amount that a charger/adapter uses but it does use it. Even smart chargers draw a very small amount of power for sensing so they can supply power when it is demanded.

Depending on the charger/adapter they either use a wound coil system or a solid state circuit or a combination of the two to bring the normal 240 V power supply down to the power requirement of the device. If turned on at the power source these circuits whether coils, Solid State, or combo are always drawing power and as a result they normally feel warm/hot if touched. So the best option to save your money is turn them off at the power source when you have finished charging or using the device they power.

Many devices in the home run similar systems to keep power on a circuit for faster startups of things like TVs, Computers, and such. This “standby” power is very small but it is still using electricity and so adds to the power bill or the drain of your batteries and power sources. So it is better to turn them off at the power point when finished using them if you want the greatest power saving rather than convenience (which some may prefer).


Yes - if the power outlet is switched on, any device plugged into it that can be used by simply connecting a target device (phone, tablet, vacuum cleaner) or switched on remotely (television/etc) will consume power when not ‘in use’ …


It is slightly more insidiousness because an increasing number of devices now have ‘smart switches’ that even use a small amount of electricity for their switch and internal electronics. Gone are the days when an on-board switch always broke the electrical connection.


While I see Saint @grahroll (;))has already been here days before me to answer this question, I will add my considerations to the discussion.

As a separate mention before getting into details, did you receive the keg of apple cider yet @BrendanMays? My wife said it was just wasting space, and so I thought of you. Again, addressed to Brendan in Sydney, so may take a little while to get there but I’m sure all the posties know you ;).

I suggest that Choice should do some testing. I have USB chargers scattered all around the house and cars (and office when I have a job), and two ten-socket chargers within my reach as I type!

Additionally, I use power-boards that have individual lit-up switches for each item you plug in. I would be interested to know how much current is trickling through these all day and all night - and how much it differs between:

  1. Switch off, nothing plugged in;
  2. Switch off, something plugged in;
  3. Switch on, nothing plugged in;
  4. Switch on, something plugged in but turned off;
  5. Switch on, something plugged in and turned on.

Similar kinds of fiddling might be done with a few makes of charging device - but to these I would add the condition ‘object plugged in is fully charged’.

I want to know whether my wife is right in turning off the switches to the dining room TV, BluRay Player, and Android box that I still haven’t set up, as I don’t use them particularly often. I am interested in finding out how much money we are wasting on these trickles of electricity - separate to the device itself that is on standby, because as Choice tests show this can vary enormously.


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Yes they do use power if the power point is turned on, but the significance of the power use depends on the particular charger. A small USB charger can use almost no power, ~1W when not charging, which is barely detectable. They don’t run warm when not in use, demonstating the minimal power dissipation. Over a year, if paying say 25c/kWh, then leaving it on 24/7 it will cost you about $2 per year.

Larger, and especially older type power supply/chargers that have a transformer energised all the time, will use significantly more energy over time.

IMO all electronic devices that are energised when not in use pose a very small, but not zero, fire risk, so best to turn them off.


good rule of thumb - if it feels warm to touch it is drawing power