One of the best iPad and iPhone chargers is sold by Apple and comes with every new iPad. The Apple 12W USB Power Adapter can charge an iPad slightly faster than the old 10W USB Power Adapter, the prongs fold down for easy storage when traveling, it works great with any iPad or iPhone, and it costs only $20 (or a few bucks less on Amazon). But it can only charge one device at a time, so if you need to charge multiple devices, you need to multiple power adapters and access to multiple plugs. For just a few bucks more, you can get Kensington's new AbsolutePower 4.2 Dual Fast Charge for Tablets and charge two iPads and/or iPhones at the same time. Kensington sent me a free review unit a few weeks ago and I've been testing it out. While it has a few drawbacks, I've found it to be so useful that I recommend you consider this product if you are in the market for an additional iPad or iPhone charger.
USB chargers are almost a dime a dozen, but they are not all built the same. To charge an iPhone as fast as is safely possible, you need a device that can deliver 1.0 Amps. To charge an iPad as fast as is safely possible, you need a charger that can deliver 2.1 Amps. With anything less you get less than optimal results. For example, I have many USB chargers that provide only 1.0 Amps. They will connect to an iPad, but they only charge the iPad when the device is in sleep mode; if I am actually using the iPad, a charger that delivers 1.0 Amps can keep the iPad going but doesn't also add more juice to the internal battery.
Although some dual chargers deliver 2.1 Amps to only one USB port, the Kensington AbsolutePower 4.2 delivers 2.1 Amps to both USB ports at the same time. Thus, you can charge two full-size iPads and/or iPad minis using just a single plug. If you instead plug in an iPhone, the AbsolutePower will deliver the 1.0 Amp required to safely give your iPhone the specific power that it needs. Note that you use your own USB cables; no cables come with this product.
The time that it takes any charger to recharge an iPad or iPhone is going to vary from test to test and from device to device. But to give you some rough estimates, in an hour, the AbsolutePower 4.2 would add around 20% charge to my third generation iPad and would add about 35% charge to my iPad mini. For my iPhone 5, an hour was enough to add about 65% charge. Thus, I could bring my iPhone up to 100% in less than two hours (depending upon the charge that I started with), whereas I would usually leave iPads plugged in overnight to get a full charge. These numbers are similar to what I see using the Apple USB power adapter, so you don't seem to be losing anything by using the Kensington AbsolutePower 4.2 to charge two devices at once.
Only having to use a single outlet plug to charge two devices was sometimes useful at my home or office but was extremely useful when I traveled. I often find only a single outlet plug free in a hotel room, and with the AbsolutePower 4.2 I didn't have to decide which lamp in the room to triage to make room for a second charger. Similarly, last week I was waiting for a plane in San Francisco after taking some depositions and I found a seat next to an outlet with two plugs but someone else was already using one. With the AbsolutePower 4.2, I was able to use the remaining outlet plug to add a significant charge to both my iPhone and my iPad at the same time so that I had power for both of my devices for the long flight back to New Orleans.
Because a device like this is so useful for travel, one of my two gripes is that this device could have been better designed for travel. I love the ability to fold down the prongs on the Apple USB Power Adapter and I wish that the AbsolutePower 4.2 shared that feature. What you can do is press a small button and easily slide off the two prongs. This does makes it easier to pack this charger for travel so that the prongs didn't stick out so much in my bag — but I still wish I could instead fold down the prongs.
My only other small gripe is that the device itself is somewhat large. There were two times when I wanted to use this device but there wasn't enough space around the outlet to do so. For example, one time, I was at a conference room table that had a pop-up drawer containing a plug which could not accommodate the size of the AbsolutePower 4.2 To be fair, however, the Apple USB Power Adapter is somewhat large as well and I have frequently encountered places where it similarly would not fit.
Overall, though, I have enjoyed using the AbsolutePower 4.2. Carrying one adapter takes up less space in my travel bag than two adapters, and as someone who frequently travels with multiple iOS devices, being able to charge two devices simultaneously using only a single outlet plug is quite useful. I wish that this device was even better designed for travel, but it worked well enough for me to want to use it again and again. The device costs $29.99 on the Kensington website, but you can get it for almost $20 on Amazon — just a few bucks more than the Apple USB Power Adapter that only charges one device at a time.
Click here to get Kensington AbsolutePower 4.2 from Amazon ($21.82)