Charging phone via a usb

datlex

Hi,

Does anyone know if it is cheaper to charge your phone/tablet/kindle via the USB port on a PC/laptop?

I'm not sure if it uses energy already in the PC or whether it uses the same as it would have charging via the mains.

I know you can charge a mobile from a laptop battery but obviously this drains some of the power from the laptop.

Trying to be energy efficient without being energy frugal. e.g I let laptop charge in day whilst solar energy is working then use in eve on battery.

rogerblack

Charging a laptop battery during the day and using at night is barking, barking, barking mad.
While in principle, it may save a tiny, tiny amount of electricity, it wears the battery very significantly to the point it will need replacement months, or even years earlier.

Charging either through an external charger or a PC will be more or less similar in terms of demand at the end of the year.

Charging (for example) a nexus 7 completely 365 times a year will use about 5kWh of power - about 50p.

victor2

As indicated above, it's just not worth it.
Charge the phone/tablet/kindle from a mains adapter during the day when your solar panels are generating if it keeps you happy that you're being energy efficient.
The above 5kWh equates to about an extra 30 minutes under a typical electric shower per year - an extra 5 seconds a day, or save it for a birthday treat perhaps?

HappyMJ

Cheaper...maybe...but if so the savings are calculated in tenths of pennies per day. A non smart phone mobile phone battery may be 3.7V 800mAh. Charging from empty to full every other day would only cost 6p per year to charge. (3.7V*0.8A*180days) = 0.53kWh per year. Sorry but that's just being too frugal with energy. You need to be looking at bigger items to save money on. Heating is the big one. Anything to do with hot water is another one. Reducing shower times by 5 seconds a day as above in the previous post will save you more than what you are considering.

macman

It does amuse me when people concerned about big energy bills list all their electrical devices in intricate detail (tablets, curling tongs, electric pencil sharpeners etc), but frequently fail to even mention how the property is heated and hot watered.
Years of energy information and education has not been entirely effective...

victor2

macman wrote: »

It does amuse me when people concerned about big energy bills list all their electrical devices in intricate detail (tablets, curling tongs, electric pencil sharpeners etc), but frequently fail to even mention how the property is heated and hot watered.
Years of energy information and education has not been entirely effective...

The government didn't help with all the advertising telling people to switch their TV off at the wall rather than leaving it on standby. I can leave mine on standby for an annual cost of about 20p, and it's nothing special.

prowla

No, a PC's load varies according to how much power it is using.
Of course, though, you could not identify the incremental extra used by charging a phone from it.

NowRetired

I turn my PC off each night but leave it plugged in and the socket switched on.


I have a USB battery charger with 2 re-chargeable AA batteries permanently plugged into my computer and the batteries are always getting charged up.


These batteries are for my wireless mouse.


I also sometimes plug my phone in as well.


And anything else that can be charged that way.


Probably save myself 50p a year doing that.

prowla

NowRetired wrote: »

I turn my PC off each night but leave it plugged in and the socket switched on.


I have a USB battery charger with 2 re-chargeable AA batteries permanently plugged into my computer and the batteries are always getting charged up.


These batteries are for my wireless mouse.


I also sometimes plug my phone in as well.


And anything else that can be charged that way.


Probably save myself 50p a year doing that.

How do you save by doing that?

Cardew

NowRetired wrote: »

I turn my PC off each night but leave it plugged in and the socket switched on.


I have a USB battery charger with 2 re-chargeable AA batteries permanently plugged into my computer and the batteries are always getting charged up.


These batteries are for my wireless mouse.


I also sometimes plug my phone in as well.


And anything else that can be charged that way.


Probably save myself 50p a year doing that.

Are you saying that your USB sockets are 'live' when your PC is switched off?

How do you 'switch off'? also laptop or desktop PC?

If your USB sockets are live(and I have never seen that condition), then the PC itself will be using power. The only way power can get to the USB sockets is from the PC power supply which is converting the 240v Mains AC voltage to the DC voltage at the USB socket.

The power consumed by the PC itself will be far more than the power taken by the charger/phone

So rather than saving money you will be spending far more than simply charging from a 13 amp socket.

Get a plug in power monitor(costing £10 or less) and you can measure how much power your PC is using when it is what you consider 'switched off'.

DragonQ

USB sockets can provide power when the PC is turned off. This is usually an option in the BIOS/UEFI of modern PCs, so you can turn it off to save a bit of energy. Probably 1 W or something.

For what it's worth, I charge my phone at work usually. Every little helps.