Usb power ?

waptext

Ive just purchased a pure chronos idock clock radio that has a usb socket in it too, would it consume more power if i use it to charge ?

I currently use my laptops usb to charge my iphone and a nokia sometimes also a usb battery charger sometimes also my laptops usb speakers are always connected , does it drain more power from the laptop or does it not make any difference ? , looking to use the least power (ie moneysaving) and best performance ??

Avoriaz

waptext wrote: »

Ive just purchased a pure chronos idock clock radio that has a usb socket in it too, would it consume more power if i use it to charge ?

Yes.

If you plug a phone in to charge from a clock or laptop that will cause that device to draw more power from the mains or laptop internal battery. The energy required to charge the phone isn't magically created.

Whatever you use to charge devices will consume the same amount of power (ignoring any minor differences in efficiencies).

You will not save any money by changing the method of charging, although the cost of charging a phone is so small anyway as to be insignificant.

Your only concern should be whether the USB outlet on the clock is suitably configured to power your device.

It probably is but read the manual and check.

Although why bother if you already have suitable charging methods that you know work.

Avoriaz

Further to the above, not all USB sockets and chargers are configured identically.

Here is a thread of mine from earlier this year that covers that.

whowants2brich

you will almost definitely find that there is no power connected to the usb socket, and that it is only a host socket so that you can plug in a usb stick or card reader, and use that music to play through the clock to wake you up, rather than listening to radio...

also, don't try to charge the phone via anything that wasn't designed to charge the phone - unless you want to potentially ruin the warranty/battery! (it might do no harm whatsoever, but if you have a normal and specific charger next to the clock, probably best to use it)

Avoriaz

whowants2brich wrote: »

you will almost definitely find that there is no power connected to the usb socket, and that it is only a host socket so that you can plug in a usb stick or card reader, and use that music to play through the clock to wake you up, rather than listening to radio.

There probably is power there.

If it is this radio then the specs state:

"USB PowerPort for charging mobile devices".

Although the OP won't save any money by using that port instead of any other port to charge his phones etc which I think was his main question.


As you suggest, he is probably best off using the charger designed for his phone although there is very little likelihood of the radio damaging his phone.

waptext

Avoriaz wrote: »

There probably is power there.

If it is this radio then the specs state:

"USB PowerPort for charging mobile devices".

Although the OP won't save any money by using that port instead of any other port to charge his phones etc which I think was his main question.


As you suggest, he is probably best off using the charger designed for his phone although there is very little likelyhood of the radio damaging his phone.

yeah thats it

esuhl

whowants2brich wrote: »

you will almost definitely find that there is no power connected to the usb socket, and that it is only a host socket so that you can plug in a usb stick or card reader...

A USB port provides 5 volts of power, and (from memory) 500mA (for USB 2.0) or 900mA (for USB 3.0) of current... although I think the specification of "dumb" (no data) USB sockets might have been upgraded to allow larger currents for battery charging. I think that's the gist of these articles:

• http://www.extremetech.com/computing/115251-how-usb-charging-works-or-how-to-avoid-blowing-up-your-smartphone
• https://en.wikipedia.org/wiki/USB

Anyway, the device you're charging will use electricity to charge the battery (obviously). But whether it's cheaper to charge a device from your laptop or the clock-radio will depend on how efficient they are (which is tricky without a degree in Electrical Engineering and dismantling everything!). I doubt there's much in it.

• If you're using the USB 2.0 port on your laptop, that provides a maximum of 500mA (0.5A) of current at 5V, i.e. 2.5W.
• A kilowatt-hour costs about 12p (I think; very roughly).
• There are 8760 hours in a year.
• So, if the device was charging at full power 24 hours a day, 7 days a week, for a full year...
• That would be 0.0025kW X 8760h = 21.9kWh... or £2.63.

Plug it in for just 2hrs a day, and that's 22p a year...

Or, if you have some fancy device like the iPad which can draw 10W of power (although it wouldn't be able to do that from your laptop), it could cost as much as 88p a year (if you charged it for 2hrs a day)!

agrinnall

esuhl, your USB link confirms that changes to USB 2.0 spec increase the available current to 1A and then 1.5A, which concurs with my experience of powering an external hard drive that required connection to two USB 1.0 ports on my old laptop but only one USB 2.0 port on my now not-so-new laptop.

Nilrem

agrinnall wrote: »

esuhl, your USB link confirms that changes to USB 2.0 spec increase the available current to 1A and then 1.5A, which concurs with my experience of powering an external hard drive that required connection to two USB 1.0 ports on my old laptop but only one USB 2.0 port on my now not-so-new laptop.

The change to USB power in the USB2 spec was only for when used with a dedicated charger (it was a change in the spec for the device side of the USB spec, not the host/computer).
The Spec for power from the USB host (IE motherboard on your PC), didn't change at that point.

However there are a few things that did change such as.
Some USB1 chipsets had issues supplying the full 500ma per port - most people wouldn't notice with most devices, but things like the early USB ADSL modems BT supplied were notorious for being unreliable because of it (they drew right on the edge of the limit), as did some things like USB powered scaners and drives.

Those issues largely cleared up with USB2 as the tech had matured - although you still find devices that are very picky about the USB ports they'll work with because they draw close to the limit (I had fun sorting out a Cannon Lidl scanner for a friend, it was completely USB powered and it turned out only wanted to work if it was in a USB port on the motherboard on it's own, or in his Monitor's built in hub).

Some Motherboard manufacturers deliberately broke the USB power specification for some of their USB ports when it came to USB 2 - things like designating a pair of usb ports (usually the ones you would connect to the front headers on your case) as "high power" and using a third party usb chipset that allowed more current (I think both Gigabyte and ASUS made it a marketing feature that you could charge your Ipad etc from those headers).
I've got a couple of motherboards that from memory offer that (they also often keep the power to those ports running when the machine is off)

Also some devices, laptops especially limited the amount they allowed per usb port because it would drain the laptops own battery too fast.

It was only with USB3 that the normal power allowed to be drawn from the host has increased, to all of 900ma whilst the device is able to communicate with the PC (I think it allows more if the device is just charging).

esuhl

Nilrem wrote: »

Some Motherboard manufacturers deliberately broke the USB power specification for some of their USB ports when it came to USB 2...

Yeah... I seem to remember having a Foxconn motherboard that (I later found out after much frustration) could only supply 450mA of current to the USB ports, preventing certain devices from working.

Zeus_10

Also if you charge it through some sort of device, it takes longer for the phone to fully charge. I bought a portable charger a while back. On a full charge, it charges my iphone fully about 3 times.