Are the power adapters interchangeable if you already have a kindle? Thinking of buying my hubby a new $79 kindle for a gift. He would read ONLY on it, and not do anything else. Should I buy the adapter, or can we just use mine for both? Any ideas?
USB 2.0 is a standard. That means an adapter like the Amazon Kindle power supply/adapter, and any device (power user) that has a USB connector like the Kindle itself must meet "USB rules". Those USB rules means that all USB 2 adapters, users, etc are compatable. Any USB 2.0 adapter can be used with any USB 2.0 device. This is so you don't have to worry about the different voltage, current and power differences.
By the way, in direct response to Ivan, the numbers on the adapter and/or devices are usually ranges or nominal, they all work together, because it is a standard. If you really do want to worry about the numbers, you can read the USB specifications, otherwise just know that all USB 2 adapters and devices are compatable regardless of what numbers are printed on the adapter or device, with the only exception being the USB adapter input voltage.....where an input voltage of 110v - 240v means you could actually use the adapter in europe, africa etc, where the standard voltages are 220-240v, and the standard voltage in USA is 110-120v. You CANNOT use a 110-120v input adapter in europe, africa, etc, because it would burn up. Regardless, the output is the same and compatable on all USB 2 adapters.
Ignore the USB 2 voltage, current and power ratings, just like you ignore the voltage, current and power ratings when you plug a 110v plug into the wall socket. USB 2 is a standard just like the wall socket.
By the way, just to add to your confidence, I am an electrical engineer who used to work with USB interfaces, I know a little about it. Gerald
This is for everyone asking similar questions. You do not have to be concerned about voltage, watts, amps, etc. with USB plugs. All USB devices use the standard for that type of device and they are work basically the same way. Regardless of what the device you are charging says about its amperage requirement (0.85A vs 500 milliAmps or 0.5A or even 1.0A) they all work on the principal of having the device being charged determine the max draw from the source. As long as your USB supply is providing enough power to trip the charging circuit, the amount the device will use is whatever the source can supply up to the stated limit. Most USB ports and/or adapters are capable of supplying 1-1.5A, so as long as your device doesn't need more than that, it will charge just fine. You do not need to worry that there will be too much amperage since that is determined by the device being charged. Even if the USB port supplied up to 5A, it would still be fine to charge a device requiring only 0.85A. I hope this lets everyone relax about this. For those who already have a mains powered USB converter socket, yes it will work to charge your Kindle, iPhone, telephone, etc, etc.
Actually I've been using the charger above for most of my needs - it easily charges my Kindle Fire [first gen] as well as my Kindle 2 and my Samsung Galaxy Stellar Smartphone. On the plus side it does NOT heat up like the factory shipped charger that came with my Kindle and it does charge things a bit faster than the original charger as well.
Just came upon this although it is an old posting. Just a practical note...W. Redmond is exactly right. I have used various phone chargers with USB ports with my Kindle 3 for a couple of years. No problems whatsoever. If it has a USB 2 port it will work. No worries!
The new $79 Kindle and the 2 new Touch Kindles both have a USB 2.0 cable that will plug into this adapter or something like Belkin Mini Surge Protector Dual USB Charger(not endorsing this, just using as an example). If your cell phone uses an adapter with a USB port you can even use that.
The only Kindle that I don't believe this will work with is the 1st generation Kindle which has a dedicated charger and doesn't charge via a USB cable. All the others charge via a USB cable and if you already have a power adapter from a K2 or K3 you don't need to buy a new one. It's the same thing.
@Rita Reader: Unless your Kindle is a 1st generation you will be able to use your old adapter for the new $79 Kindle.
Thanks for your reply. I'm still a little wary about it, though. The reason being is that, while everything you've described points to the standard as the way USB works, in reality, devices regularly deviate from standards with some nasty and expensive results. There have been tons of stories of people plugging their phones into the wrong charger and killing their phones, assuming that a USB connector means standard USB power, when it often does not. The way the standard is supposed to work is that USB will not provide more than 100 mA unless the charging device requests more, up to the maximum of 500 mA. In reality, there are USB cell phone chargers that will push 1 A or more. Now, what I don't know is how intelligent many of these chargers are. As I mentioned before, they should only provide 100 mA unless the device requests more, so how is one to know which chargers are smart enough to adhere to that process? Will most devices have a failsafe where they'll limit current if it exceeds a certain threshold?
EDIT: It looks like that process is a bit older, and has now been augmented with a special standard for wall chargers. http://www.maxim-ic.com/app-notes/index.mvp/id/4803
Amazon has not been clear concerning these power adapters. The picture looks like the one that came with my second generation Kindle. Will my second generation adapter work with the new Kindle Touch, is the question?
Since you said she received it last Christmas, it is still probably under the 1 year warranty. If so, you will be able to contact Amazon Kindle Customer service with any questions or problems that arise. Just say it was a gift. Hope this helps.