How much power do chargers consume?

reddwarf2002

Hi, I don't know if this is the right board to post this....but does any know whether chargers (for mobiles/laptops) consume the same amount of power regardless of whether it is charging the unit or not? So for example if the charger is plugged into the socket & power is ON but is not connected to the device to be charged (i.e. mobile/laptop) does it still consume the same amount of electricity as if it was actually charging the device? I know that it does consume power but just need to know whether there is any difference...

gizmoleeds

Have a look at the eletricity meter in your house and see if it spins faster when the unit is charging.

djohn2002uk

Of course it consumes more when the battery is being charged because you have the battery itself getting its charge via the charger and the dissipation within the charger.
Chargers are basically a transformer with a few other components (diodes and maybe a capacitor) to rectify the voltage into a "rough" DC. Because it employs a transformer which are inherantly inefficient, (only about 55% efficient if I remember correctly) they will always generate heat and so will consume some electricity as a waste whether charging or not.

reddwarf2002

djohn2002uk wrote:

Of course it consumes more when the battery is being charged because you have the battery itself getting its charge via the charger and the dissipation within the charger.
Chargers are basically a transformer with a few other components (diodes and maybe a capacitor) to rectify the voltage into a "rough" DC. Because it employs a transformer which are inherantly inefficient, (only about 55% efficient if I remember correctly) they will always generate heat and so will consume some electricity as a waste whether charging or not.

Thanks for the info djohn2002uk!

Would you say that it is still using about 50% of power even when it is not charging? What percentage would you estimate it at?

derrick

reddwarf2002 wrote:

Thanks for the info djohn2002uk!

Would you say that it is still using about 50% of power even when it is not charging? What percentage would you estimate it at?

Can't see the problem, when finished charging, removed the charged appliance, switch off charger, NO consumption

gizmoleeds

derrick wrote:

Can't see the problem, when finished charging, removed the charged appliance, switch off charger, NO consumption

Ah, but then you are using up the battery power of the device, so it will need charging sooner - I use a laptop at work and it is never not charging (as the battery would only last about two hours and I work 7½!). Also, when you use a laptop from battery power it may shut down or reduce the performance of some features - for example the screen may go dimmer.

derrick

gizmoleeds wrote:

Ah, but then you are using up the battery power of the device, so it will need charging sooner - I use a laptop at work and it is never not charging (as the battery would only last about two hours and I work 7½!). Also, when you use a laptop from battery power it may shut down or reduce the performance of some features - for example the screen may go dimmer.

I didn't know that was the reason for the OP.
Not being a computer boffin I would have thought that for work you could use a mains computer, but that said the OP did mention mobiles, so I am assuming they meant leaving the chargers switched on after removal of appliance as they asked "does it still consume the same amount of electricity as if it was actually charging the device?"
In your senairo yiu are actually using the appliance so it does not really relate to my answer

reddwarf2002

gizmoleeds wrote:

Ah, but then you are using up the battery power of the device, so it will need charging sooner - I use a laptop at work and it is never not charging (as the battery would only last about two hours and I work 7½!). Also, when you use a laptop from battery power it may shut down or reduce the performance of some features - for example the screen may go dimmer.

Yes, the question was more to do with laptops than mobiles but I wanted to make it sound in more general terms so that everybody understood what I was trying to say. There are several scenarios but I didn't want to complicate the post. Maybe the way I asked the question was not very good...

If I can now rephrase my OP, my post would have read exactly as gizmoleeds has stated. I use my laptop from the mains power and really wanted to know how transformers (chargers) work & how much power it consumes. Would I be right in thinking that the charger actually used the same amount of power if the laptop is powered from the mains (but not charging battery) as if it was just charging the laptop (laptop not being used/ON)? Also what if the charger is just plugged in on wall socket by accident (power switch on) but not connected to the laptop? What difference would that make to the power consumption? I hope the above is clear....this is why I didn't go too deep in explaining on my original post...gets quite confusing...

John_Gray

I've just plugged the charger of an "IBM" (=Lenovo) Thinkpad R50e into a 13A "consumption meter", and the figures for the charger consumption are:

2W when not connected to the laptop
between 12 and 19W as the laptop powers up
12W once it has fully powered up and awaiting user input (battery is 99% full)
17-21W when the battery was down to 92%, but no other activity on the laptop

The figures could vary depending on a whole heap of factors, hard disk power consumption, whether the disk was still spinning, what was on the screen (number of pixels lit), and so on. Also: Your Laptop May Vary...!

John