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spartans
spartans • Dec 30, 2009

mobile phone charger

am 2nd yr student in electrical engineering
i have read in a news paper that there will be 30% losses when we connect a charger to power supply even though there is no mobile connected to it
am just confused how there can be so much loss
I think when you use adapter for charging your mobile
There is a transformer used in it
while it is converting high voltage to low voltage ..some amount of electrical energy is converting into heat energy
ie why there may be some looses I don't remember the exact name of this process?
I hope I am right
for more information you can refer any 12 th standard book of physics
spartans
spartans • Dec 30, 2009
i know that even though there is no load on secondary winding of the transformer there will be current passing through the primary winding and hence there may be losses but am shocked that are they really up to 30%
if its alone not responsible for all the losses then what can be the other losses?
silverscorpion
silverscorpion • Dec 31, 2009
Well, I dont think mobile phone chargers have transformers in it. If transformer is present, then the charger would be heavy. Definitely heavier than what it is now.

I think the AC power is rectified as it is using a rectifier so that 220V AC is converted to 220V DC. Then, that DC is reduced to 3 or 4V using buck converter (DC-DC converter).

This buck converter wont be consuming so much power without load. So, I think 30% wastage of power is an exaggeration. We can never be sure, though..
reachrkata
reachrkata • Dec 31, 2009
Agree to that. Perhaps a part of the loss is due to loading itself. Sometimes, certain switching supplies tend to go into instability when not loaded at all. Therefore they are always loaded internally (using resistors) to keep the supply operating stably.
This could be the efficiency loss.

-Karthik
😁
Christopher6
Christopher6 • Jan 1, 2010
Re: Modifying Mobile Phone Charger for More (Higher) Current

Hi,

I have an Nokia AC-3 charger that came with my Nokia 2600 Classic Mobile Phone.

AC-3 Charger gives just 5V with 350mA current. But, my old Nokia ACP-12 charger gives 5.7V with 800mA current. With this new charger, my phone takes 3 hours to charge fully.

I am using an CA-44 (Local) adapter with the ACP-12 charger and with this, my mobile phone takes just 1 hour 15 minutes... [​IMG]

So, now i want to modify the AC-3 charger to get at least 700mA Current from it. So, what do i have to do it. I think these chargers are Switch Mode Power Supply types.

Thanks in Advance,
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spartans
spartans • Jan 1, 2010
i have got some information about transformers used in mobile chargers from my frnds and that is
most transformers are the old style, which are essentially a short circuit over a coil to make a magnetic field and convert the power down to a usable voltage. When nothing is connected these transoformers just choke on their own eddy currents in the transformer...and burn power.

Newer cel phone chargers dont use the old wall-wart brick type transformer; rather they have an efficient switch mode power supply that runs at very high efficiency (excluding power factor); and these newer models dont use much if any power with nothing connected. Smarter ones even shut themselves completely off when nothing is connected - sadly these are rare.


more over even if there are 30%losses the 5W that the charger uses to charge your phone, 30% of THAT is 1.5Watts. 600 Hours to waste one unit of electricity
water2
water2 • Jan 8, 2010
spartans
i have got some information about transformers used in mobile chargers from my frnds and that is
most transformers are the old style, which are essentially a short circuit over a coil to make a magnetic field and convert the power down to a usable voltage. When nothing is connected these transoformers just choke on their own eddy currents in the transformer...and burn power.

Newer cell phone chargers dont use the old wall-wart brick type transformer; rather they have an efficient switch mode power supply that runs at very high efficiency (excluding power factor); and these newer models dont use much if any power with nothing connected. Smarter ones even shut themselves completely off when nothing is connected - sadly these are rare.

more over even if there are 30%losses the 5W that the charger uses to charge your phone, 30% of THAT is 1.5Watts. 600 Hours to waste one unit of electricity
I asked my boyfriend. what he told me is similar with what you said.

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