Electricity usage question

[Carbide X]

Hello,

I was wondering... When you leave the charger in the plug, does it also use electricity when its plugged or only when you plug your phone (or what ever device) in the charger

[Godlygamer23]

The charger itself might consume some power(very little), but aside from that, it's not consuming any electricity. You can prove this by feeling the housing of the charger with it just plugged into the wall - it'll feel cool. Whereas when you plug a device into it to charge, it'll get fairly warm after a bit of time.

[Mira Yurizaki]

3 minutes ago, Carbide X said:

Hello,

I was wondering... When you leave the charger in the plug, does it also use electricity when its plugged or only when you plug your phone (or what ever device) in the charger

There's awalys some amount of power being consumed. If the charger is a high quality one, it's usually very minimal on the order of a couple milliwatts.

[Maximusfoximus]

I agree that some power will be used, but it will be so minimal it will probably be less than a cent on your electricity bill. This will be true even if you have an LED indicator on your charger. 

[EsaT]

Power consumption is directly related to how warm charger is when in plug.

Old linear transformer based chargers usually run warm pretty much always.

Modern switch mode power supply based chargers can be very efficient in standby.

[mr moose]

1 hour ago, Carbide X said:

Hello,

I was wondering... When you leave the charger in the plug, does it also use electricity when its plugged or only when you plug your phone (or what ever device) in the charger

Short answer: no, switchmode power supplies (what nearly all wallwarts are now) need a load to run, no load = not on.

 

Long answer: yes, but it's so small you won't notice it.  From a safety point though it is better to leave them turned off if they are not in use.

[Christophe Corazza]

 

2 hours ago, Carbide X said:

Hello,

I was wondering... When you leave the charger in the plug, does it also use electricity when its plugged or only when you plug your phone (or what ever device) in the charger

 

Short Answer: YES

Long answer; Since you’re asking about the charger, let's talk about that.

A charger basically converts AC to DC to charge the device connected to it.
Typical household voltage, for example in Europe, is 220 V. So the charger would take that 220 V and convert it into some lower voltage (around 5 V for a mobile phone charger). 
For this operation, there are a few steps involved, but to keep it as simple as possible:

1. A transformer steps down the input voltage to the working voltage.

2. A rectifier converts AC into DC.

3. A filter smoothens the output of rectifier (reducing ripples).

4. A regulator generates a steady output signal.

Now, coming back to the question, how is the charger consuming power when no device is attached to it (and the power supply is ON)?

Blame the transformers. A transformer will consume some power, though negligible, even in no load condition. This is the case here:

When the charger is connected to the mains AC supply, the first part of the circuit is the transformer that steps down the voltage. Since, there is no load or device connected to the other end, there will be no current flow in the circuit other than the transformer’s primary winding. Although, the power consumption will be very low. there will always be some current flowing in the primary winding if the power supply is ON.

Not just transformers are the culprits. The electronic components used in the circuit after the transformers also consume  power. Though this power consumption is very very low as well.

In general, the power consumption of such chargers or wall adapters in no load condition is between 0.1 - 0.5 W. That’s not much, but when all these stand by powers are combined together, it can account for a decent percentage of the household consumption in a year.

[TheKDub]

2 hours ago, Carbide X said:

Hello,

I was wondering... When you leave the charger in the plug, does it also use electricity when its plugged or only when you plug your phone (or what ever device) in the charger

Yes, however it's a negligible amount.

 

(US)

According to https://www.howtogeek.com/231886/tested-should-you-unplug-chargers-when-youre-not-using-them/ it took chargers for the iphone 6, ipad air, macbook air, surface pro 2, samsung chromebook, and nexus 7 to draw a mere 0.3W. That's approximately 0.05W per charger assuming they all consume the same amount of power when their device is unplugged.

 

That's only 438W per year. In the US, the average electricity cost is about $0.13/KWH, so that means one of those chargers would only cost about $0.06 to have plugged in for an entire year.