Background
Almost every gadget today is charged over USB. It seems like a good idea since everyone has a computer with USB, but fumbling behind a computer and making sure that computer is on and does not sleep for the duration of the charge is a pain, not to mention you need to unmount drives and stop syncs as soon as your devices are plugged in.
USB wall chargers to the rescue! However, having gone through half a dozen different ones that all seem the same based on the back of the box, I have not found one that works with all my devices.
I have the following devices that I would like to be able to charge:
- iPhone
- XBox 360 controller
- PS3 controller
- Sony Reader PRS 350
These are all "normal" devices in that they (1) can be charged by being plugged into a computer without any additional software/drivers installed and (2) can even be charged by plugging them into some other device such as a network router, a printer, an AppleTV etc.
But I've had endless pains trying to find a USB wall charger that works with everything. The Apple wall chargers don't seem to work with any other devices and vice versa (unless you get one specifically marked as compatible with iPod/iPhone). The PS3 controller seems to reject almost all wall chargers, and worst of all is the Sony Reader which I have to date had 0 success with.
But all these devices work when you plug it into a computer or even a network router.
So…
Question
Does there exist a wall charger that (1) has enough circuitry to act as a USB host allowing all my devices to be charged and (2) is just a simple wall charger, not a big honking device that serves some other purpose and needs a big honking adapter?
Addendum: It's about how, not how much
Plugging the devices into my computer one at a time and profiling the USB, I see each draws this much power from the host:
- XBox 360 controller – 500mA
- PS3 controller – 500mA
- Sony Reader – 500mA
- iPhone – 1000mA
The iPhone uses more because there's some proprietary stuff going on between the Mac and iThings, but they charge fine with 500mA as well, just not as quickly.
All the wall adapters I've tried were rated to be at least 2A so should easily have covered any one of these devices individually from a pure power standpoint.
From my testing, it seems like the devices simply are not accepting any amount of power when only given it over the 2 power pins of USB. You need to either (1) short some pins in order to fool the device into thinking you're a wall charger made by the original manufacturer or (2) be an actual USB host.
(1) is the solution that most wall chargers provide since it's cheapest. The problem is the pin shortings required seems to be different for each manufacturer and it's impossible for any particular charger to cater to all of them.
(2) is what I'm looking for. It seems like there's some kind of handshaking that happens between a real USB host (like a computer or network router) that tells the device: you can safely charge. The problem is that based on what's written on the back of the box, there's no way to tell if a charger is (1) or (2), if a charger that provides (2) exists at all.
Best Answer
Sony PS3 AC adaptor
I have found it! The amazing PS3 adaptor does the job. It is a full USB host and will charge any USB standards compliant device under the sun!
Details
After spending weeks going through dozens of generic and not so generic wall to USB power adapters, some of which work with some devices, and some that work with others, the PS3 adaptor worked with everything. I literally threw a dozen different USB devices at it and it charged them all flawlessly. Victory!
Even though it says it is only compatible with PS3 accessories, it appears to be an actual USB host, which intelligently does a USB handshake with the slave device before charging. The slave device can specify how much load it needs in this handshake, up to 500mA as per the USB standard, the host provides the power, and when the slave device is fully charged, it asks the host to stop and no more power is exchanged.
As opposed to the USB Charging Port, which is simply a "dumb" power port with data pins shorted, this adaptor does a full handshake, and therefore anything you can charge with a PC without special drivers, you should be able to charge with this adaptor. This also won't overcharge your device since power isn't just constantly supplied like in a dumb port. Other users have attested to the same.
Testing with the Sony Reader
In my own experience, this clearly shows when charging the Sony Reader. I have previously charged this device using a UCS standard mobile charger. The charging light immediately goes on and there is otherwise no other reaction from the device (the device does correctly charge).
When using the PS3 charger on the other hand, connecting the charger does not result in the charging light to go on. Instead the Reader turns on, boots up, shows on screen: "USB connected", then "USB charging". At this point, after the handshake, the charging light goes on. When fully powered, the screen displays: "USB charging complete". This behaviour is identical to when you plug the device into any other full USB host such as a PC.
Notes & Conclusion
Because the PS3 adaptor is a standard USB 2.0 host, it only gives up to 500mA as per the spec. There are 2 USB sockets in the adaptor and each is rated at 500mA, however those cannot be combined to output 1000mA, unlike the dedicated charging stations.
Therefore charging speed for your devices will be comparable to plugging them into a computer rather than a wall charger, and devices outside of the USB spec that require >500mA (eg. the iPad) will not be charged.
This however is not an issue for me. As noted in the original question, my concern is only with maximum compatibility, not maximum power or charging speed. And to that end, the PS3 adaptor works perfectly :)