Charge my Ipod in the Wall?
October 14, 2008 6:39 AM   Subscribe

I have a USB A/C adaptor for my LG Dare (usb cable goes into phone, usb side goes into adaptor, adaptor goes into wall). I have a 5G Ipod Video. Can I use the adaptor to charge my IPOD without killing the battery/IPOD?

The adaptor has these stats on the back:
Input: 100-240V - 60/60Hz 0.2A
Output: 5.1V -- 0.7A.

posted by sandmanwv to Technology (6 answers total)
Best answer: USB devices are all rated at a standard 5V DC. The USB adapter should be completely interchangeable with any other. So yes.
posted by le morte de bea arthur at 7:31 AM on October 14, 2008

lmdba, I have a Garmin Forerunner 305, a Motorola Razr, and an iPod, all of which are charged by connecting a USB cable either to a computer or to their individual wall charger. All three will charge with the computer, but none will charge by connecting them to the other wall chargers, if that makes sense. YMMV.

My guess is that the wall chargers output a tiny bit more amps or voltage to charge faster than the USB port.

To answer the question, I think it'll either work or it won't, but it won't fry anything.
posted by spikeleemajortomdickandharryconnickjrmints at 8:10 AM on October 14, 2008

Some things have OS specific drivers to change the output amperage of the USB bus, they may not charge without it. In theory the wall plug puts out the correct amperage for the specific device. For instance I use 'bcharge' on my Linux laptop to make my Blackberry work without the Windows software:

bcharge is a program that sends a special handshake to all BlackBerry
devices it finds on the USB bus. This handshake causes the device to
reset itself, and then request 500mA instead of the usual 100mA. This
allows proper charging on Linux.

I too would like to know the definitive answer to this conundrum.
posted by zengargoyle at 8:21 AM on October 14, 2008

It seems likely then that some adapters behave as more than a 'dumb charger', and require some sort of handshake with the software in the device.

I have a mains travel adapter with a USB output and it charges all of my USB-chargeable devices without any problem, but I guess that might not apply to all devices.

Either way, I can't imagine that you'll damage your IPOD by trying the phone adapter.
posted by le morte de bea arthur at 8:38 AM on October 14, 2008

There are several issues that might explain difficulties of charging batteries using a particular device or adapter.

In the original USB spec, when a device is first plugged in, the device must limit its current draw to only 100 mA. Then the device can request permission from the host controller to draw up to 500 mA. Since the host controller is the only one who knows how much power is available at the port, it is responsible for parceling out who get what amount of power.

Some adapters are just simple wall wart power supplies with no USB intelligence. This means they have no way of communicating with the target device and therefore no way of giving the target device permission to draw more than 100 mA. Even though the adapter can supply high power, the device will not use it. So the target device will either try to charge the battery using this low current, taking 5 times as long, or it may simply refuse to try to charge at all since it can't get the 500 mA it requires. So whether a given adapter will work with a given device depends on both the smarts or lack of in the adapter, and the type of charging circuit in the target device (whether is requires 100 mA or 500 mA).

However, there is a new USB specification released a little over a year ago to handle battery chargers. It allows a device to determine whether it is connected to a high-power adapter without requiring communications software by means of hardware detection. In order for this to work, both the adapter and the device must have these new capabilities. This spec is fairly new so I don't thing there are many commercial devices on the market that incorporate these new features. Presumably eventually these adapters and devices will be labeled as supporting the new battery charger features so that a single universal charger will work. I don't think we are there yet.
posted by JackFlash at 11:34 AM on October 14, 2008

FWIW, My son has an iPod touch. I have a car cigarette lighter to USB charging adapter. The adapter works with most USB devices to charge them. However, it doesn't work with his iPod, or with my iPod nano 3g. Neither device was fried, but they didn't charge.

My meizu mp3 player, and my old sony cliƩ charged right up with this adapter.
posted by vilcxjo_BLANKA at 12:33 PM on October 14, 2008

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