Kensington Charging Dock with Mini Battery Pack

Updated 7 Oct 2011

There are 2 kinds of iPhone docks - one is meant to take sound from your iPhone and play it through speakers, and the other connects your iPhone to a computer. The former is far more popular and a wide range is available, from the cheap to the exorbitant. The choices for the latter are far more meagre.

I was looking for an iPhone dock to sync for the following reasons:

• use my iPhone as a clock/photo frame
• sync more easily
• less damage to iPhone's dock connector port (the original cable has hooks)

I naturally started by looking at Apple's offerings. There were 3 options:

1. iPhone 4 dock ($40) is the first choice. It has the best fit, and "audio porting". However, it's a very tight fit - for the naked iPhone 4. It won't even fit iPhone 4s with Invisibleskin, which is probably the thinnest a case can get. No hope for my Etch then. I was not prepared to take off the case every time I wanted to dock.
2. Universal dock ($70) fits all iPods and iPhones, and comes with a remote control. The iPhone 4 inserts do not seem to fit a case, but the dock could be used without an insert; that way it would fit a case. Nobody knows if this is bad for the dock/iPhone. Both these docks have audio out connections, which means they are taking audio from the dock connector. The problem with this method is if the iPhone thinks the dock is an audio device, it may stop playing sound through its own speaker, like how your stereo's speakers silence when you plug in headphones. This would make the dock useless for an alarm clock.
3. iPad dock is reported to fit an iPhone 4 with case, and will be useful if I get an iPad in the future.

In the end, I got this product from the Apple store ($90):

Contents:

• Dock
• USB cable
• Battery with cover
• USB wall adaptor
• 3GS dock adaptor, I think

It seems a little expensive, but you're really getting 3 things in one:

• Dock
• USB adaptor
• Battery

The battery alone will cost about $20.

The battery is 1000mAH at 5V (5 Watt-hours), compared to the iPhone 4's 1420mAH at 3.7V (5.25 Watt-hours). That means it won't fully charge an iPhone 4, even with 100% efficiency!

Added on 7 Oct 2011:
I've tested charging the iPhone 4, and I estimate it can add about 40% of battery capacity.

The dock has some level of intelligence. If you connect it to the computer and just plug in the battery, it charges the battery:

If you add an iPhone into the mix, it charges the iPhone instead:

In fact, it doesn't charge the battery at all if the iPhone is there, even if the iPhone is full. This means it can only charge 1 device at a time from computer. I don't think this is a design flaw, I think it's a limitation of the USB specification.
The good thing is if you use the included USB adaptor, or even my Belkin one, it charges both at the same time. I wonder if it does this by measuring the maximum current the USB source can supply, or by seeing if it's a computer? The second way is easier. A good thing about the provided adaptor is it has the intelligence necessary to charge the iPod Touch (2G)

On the back is just one mini usb connector:

This means a) no chance of the iPhone mistaking this as speakers b) you can sync using a mini USB cable (fully tried and tested).

Now onto the meaty stuff: Will it blend? Will it charge and sync the iPhone 4 with a case on?

YES, if you don't use a dock adaptor. As I said, nobody knows if this is bad for the dock/iPhone. If anything goes wrong, I hope it happens to the dock first. When docked, the iPhone can move slightly forward and back (more forward than back), but not left and right. The dock connector itself feels sturdy.

If you only use it to hold the iPhone and not use the iPhone when it's docked, it should be strong enough.

Another criterion for a good dock: you should be able to dock and undock one-handed. Otherwise, what's the point? In this aspect this dock isn't very good. You can dock one-handed easily enough, but undocking takes some fiddling. It's possible, I hope to be able to undock one-handed once I get the hang of it.

The battery is pretty well designed - you can use it without the dock (the battery is also sold separately). It charges by the same mini USB as the dock, but you can't sync in this state. As you can see, the battery has 3 LEDs showing how much power it has left. These light up when charging the battery, and even when it is used to charge the iPhone, which seems like a waste of power. Much better than some other devices.

The really unique thing about this product is the battery cover - you can see it in the picture of the back of the dock. It has a notch cut into it that's exactly the thickness of the battery, so you can clip it on and use it as a stand:

While I'm at it, let's compare dock connector cables from previous generations. On the right is one from a 2nd gen iPod Touch, and the left is the one from the iPhone 4 (the 3rd gen iPod Touch also uses the same). The USB connector is more square. The other end looks the same.

Unrelated comments
Apple fans have a reputation of being delusional and buying into Apple's marketing. I never paid much attention to this until I visited forums. In there, you meet some people where that reputation comes from:

 

There are people who will explain EVERYTHING that Apple does. I won't comment on this and let you judge for yourself. I also saw a post where someone showed a picture of a MBP motherboard and said look for yourself, there's no space for another USB port!

Most of the pictures here were taken with my DSLR and they turned out really blur. It seems like 1/10 is too slow a shutter speed to use.