Is it OK to use my iPhone charger for charging other USB powered devices like the Kindle or a digital camera (with a rechargeable battery)? Can it cause any damage to the charger or to the device being charged?
Most standard USB charges for 0.5A. But not all USB are standardized - there are some that go for up to 1.8A and even the MacBook Pro is said to raise up to 1.1A when relevant. iPhone's charger do little more than 1.1A and it's pretty decent. That's why iPhone charging on regular USB usually take double the time to fully charge. iPad's charger are roughly 10W and 5V which translates to 2A.
There's nothing wrong that can happen with the charger because USB devices are made to work with the same standard voltage (about 5V). The USB hosts are only outputting the maximum energy it can provide up to what the client can receive. A 10W energy source will only give up to 10W and just 1W if the plugged device can only take 1W.
I'm no electrical specialist but...
Having bigger power supply (measured in watts) or bigger current (measured in amperes) on itself can't break any system because what puts them in movement is the difference of potential measured by volts.
Think of a light bulb and picture all USB devices are prepared to receive about 5V (actually little more). If you get a 220V and put in on a 110V nothing wrong happens, but it will be very weak. Apple's chargers only go up to 5V, which is within the USB standard. So yeah, it's all good and safe.
Regarding to USB charging, there are two kinds of USB devices:
- Dumb ones that doesn't check if they are connected to a charger and always use less than 100 milliamperes. Some use up to 500mA, but they are out of USB specs.
- Smart ones that check if they are connected to a charger and try to use full power of the charger (up to 1800mA or 2100mA).
Apple USB chargers (1000mA to 2100mA) are of the second type but doesn't follow the USB charging standard (1800mA) and aren't compatible with other smart devices that follow that standard. Only with dumb devices and other apple devices.
I have a Nuvi nav system with a mini-USB charging/sync port. It hangs when plugged into a generic charger. My theory is that the nuvi gets confused for some reason and tries to go into sync mode when it should just charge. I don't know how the nuvi charger or cable is different than a generic USB charger or cable.
So caveat emptor. But I would expect that it usually works across devices.
My iPhone cube overheated when I used it to charge an external battery which wants 2.0 A. Using USB current meter the battery was pulling 1.5 A from the cube which caused it to quickly overheat. iPhone connected to cube pulled 0.7 A.
When the external battery was connected to USB port on an old XP computer it pulled only 0.7 A during initial charging and even dropped to 0.6 A when 75% charged.
It seems that connecting the iPhone cube to a non-Apple source which wants 10 W (2 A) rather than 5 W (1 A) can cause the cube to attempt to deliver too much current and cause it to overheat and fail.
Yes, you can and it is a very good charger. See: http://www.righto.com/2012/10/a-dozen-usb-chargers-in-lab-apple-is.html and: http://www.righto.com/2012/05/apple-iphone-charger-teardown-quality.html
There is no doubt that you can't because iPhone charger is not even the same as iPad charger. The full info about this you can read here
Actually, all technicalities, manufacturers systematic operating schedules, and voltage/ amps/mA/ohms or any other current measurement aside...ALL COMPANIES manufacture product specific hardware and accessories ESPECIALLY Apple!! Otherwise what would be the point in manufacturing, buying, or choosing between different brands. In general vocabulary terms, all brands are different and work different. Putting too much or not enough current through any device in any manner is detrimental to that equipment. Broken down even more, YOU WILL BURN UP YOUR DEVICE/ BREAK IT!! They're may be a few cases that it will simply hinder performance, but why risk it?? not to mention, if you can afford Apple products in the first place, why are you cutting corners on cost of regular upkeep accessories ;)