does a cell phone charger consume power when phone is not connected?

[PG1995]

Hi

Two stupid people were having a discussion, by the way one was me, that whether the cell phone charger consumes power or not when it is not connected to the phone (assuming it is connected to the mains). I was of the opinion that it does consume power. It outputs DC current which can be thought of as a continuous push of electrons. Think of someone pushing a wall. Although, in physics terms, no work is being done, 'biological' energy is still being invested. Likewise, electrons at the tip of charger's pin which goes into the cell phone are continuously pushed but they can't flow outward. It's just like a water pump which is continuously pumping water but the pumped water is not used for any useful activity. I have noticed that charger, connected to the mains, gets hot even when no cell phone is connected. Please let me know if I'm correct. Thank you.

Regards
PG

 

[Ziddik]

no, it takes only less power if it doesn't connected to LOAD.. And it doesn't use large power just to output 5v or 4.7vdc (250,300ma current)

 

[bryan1]

Don't known what the relationship of reactive power is going back to the mains but mains chargers for phones ain't the most efficient. Now if the phone is turned on of course it consume power as it run off DC a battery. Living off the grid here for over 9 years one learns about phantom power yet to keep an inverter going some phantom power is needed. My mains based alarm clock with nothing else going won't run as the current is so low.

These days with a teenager in the house that is asked why didn't know turn that off... the response I forgot !!!! take away that privilege and he suddenly remembers for a few weeks then asks why am I cut off again. Leaving phantom power going, then the question is asked why didn't you turn it off..... I forgot.... No joke this has gone on ever since a laptop and mobile phone was given to him. The young kids of today have a lot to answer today.

In a final answer to your Question if the phone IS turned on then YES it will consume power even connected to the grid, now think of efficiencies what power comes in the same will never go out. so it may seem your phone is fully charged but if your on the grid. Yes you will be paying for it too......

Regards Bryan

 

[ericgibbs]

hi PG,
Try the following, plug the charger into the mains supply as normal but do not connect the charger output to the phone.

After about 30 mins feel the temperature of the charger body, it will be warm, so it does consume power when not charging the phone.

 

[Ziddik]

hi PG,
Try the following, plug the charger into the mains supply as normal but do not connect the charger output to the phone.

After about 30 mins feel the temperature of the charger body, it will be warm, so it does consume power when not charging the phone.

thats a good idea eric

 

[BrownOut]

Two stupid people were having a discussion, by the way one was me

Thanks for the good chuckle to get my day started. Yes, they do consume power when plugged in but not charging. But not for the reason you stated. A charger will have a transformer to reduce the mains voltage to one suitable for charging. All transformers will "leak" power when plugged in. This is due to non-ideal characterists of real transformers.

 

[ronsimpson]

Old charger that use a 60/50hz transformers do have the "leak power" problem. To keep prices down the transformers are made with a higher inductance then normal. I have looked at some chargers where half of the power is used in transformer heating. This power is consumed even with no load.

There is/was a big push to fix this! Many 'wall worts' are now switchers. Then have a no load mode where the switcher stops working. The power does not go to zero but close. There is a contest among IC vendors to approach zero current.

The best test is to plug the charger in (with no load) and see how hot it gets. The old style will heat about the same with no load/full load.

 

[Grossel]

Think about this comparison:
You shall convert the power from a motor that drive a propeller inside a pipe to make water flowing through the pipe. Question: If the end of the pipe is closed so that no water can flow - will the motor still generate effect to the axe (will there be torque at all?)?

Yes of course it will.

 

[crutschow]

As noted they do use power, but not for the reason you stated. If there is voltage but no current, then there is no power being used since electrical power is volts times amps. You water analogy is ok as far as it goes. It's true the water pump (electrical generator) will be dissipating power even with no flow, but there is no energy being dissipated at the end of the pipe ( end of wire).

 

[Grossel]

. . . It's true the water pump (electrical generator) will be dissipating power even with no flow, but there is no energy being dissipated at the end of the pipe ( end of wire).

Depending how to read that, the statement is both true and false. Any rotating propeller in water will provide energy as there is friction in the water itself, and between water and pipe inner wall.

 

[squishy36]

PG1995, you need to develop an experimentally inquisitive mind. The answer to your question is in fact something you can measure yourself. To a physicist, the answer is "Yes, it will always consume some power". The reason is you're putting matter across a voltage and, regardless of the resistivities of the materials involved, some current will flow and, unless the resistivities are zero, this current flow will result in increased jiggling of the atoms of the matter (it only takes one electron scattering event to make this a true statement). Whether it's measurable or not is a separate issue.

Your job as experimentalist is to then see if the data support this statement or not. Of course, if the matter you put across the voltage was, say, pure quartz, that current flow is going to be hard to measure. But, in the practical case of a wall wart, it will likely be made of conductors, maybe a transformer, and some active devices, so there will be current flow. The question is: how much?

 

[crutschow]

Depending how to read that, the statement is both true and false. Any rotating propeller in water will provide energy as there is friction in the water itself, and between water and pipe inner wall.

It's a very long pipe.

 

[Grossel]

It's a very long pipe.

Not true. Mine is short in lenght

 

[ronsimpson]

Not true. Mine is short in lenght

Is this getting personal?

 

[clel miller]

Correct me if I am wrong.....if it has a transformer, and the primary is connected to source voltage, the secondary is not connected, there will be magnetizing current. So there will be current, but it will be very small. But perhaps with the new digital "smart" meters, your utility company will have you on the books.....for any wall-wart that is plugged in.?
Thanks

 

[ronsimpson]

Magnetizing current on cheep transformers is high. The power company can see that on old meters.

 

[crutschow]

Magnetizing current on cheep transformers is high. The power company can see that on old meters.

House meters only read real power, not reactive power, so the inductive part of the magnetizing current is not seen. It will see the real power dissipated by the transformer in the magnetizing current IR loss in the primary and any eddy current or other power losses in the transformer.

P.S. Are "cheep" transformers for the birds?

 

[ronsimpson]

my spelling = lol
Yes they can see real power. The losses are indirectly from magnetizing current.
There is a contest to see how little copper to put into a transformer and not have it burn up with no load.

 

[KeepItSimpleStupid]

Yep, but there are initiatives to reduce that even further. USB requires some handshaking, so IC's that do this and the regulator are power hungry.

The transformer, bridge rectifier may not be a good analogy for a cell phone charger.