What’s that in my hand … a shoe?

No, it’s the USB Fever  Super Charger, one of the larger external battery packs I’ve seen for the iPhone 3G and 3GS. Unlike the separate power bricks we’ve reviewed, including the Callpod Fueltank Duo, the Super Charger is holster-style, meaning that you can actually dock your iPhone in the thing and make calls while the phone is being charged.

Now I bet I can imagine what many of you are saying … “That thing is a beast!” “There is no way!” “Why would anyone put that on their iPhone?!”

The answer is simple folks, at 3000mAh this external battery is 2.5 times the size of the 3GS’s 1200mAh battery; by carrying it, you can more than triple you battery life. As anyone who has tried to ration their way through a heavy-usage day with the 3GS’s anemic battery can tell you, that is nothing to sniff at.

Composed of shiny black fingerprint and smudge attracting plastic, the Super Charger measures approximately 4.5” long x 2.6” wide x 0.9” thick, and when the iPhone is inserted the total packages measures about 6.3″ long. By itself, the battery pack weighs 3.6 ounces.

Like any other external battery holster, the iPhone will simply slide into the cradle and dock on the plug.

One of the neater things about this external battery holster is that it does not require a new cable to work — it accepts the original iPhone cable and charges directly from a computer’s USB port.

Look at all the lovely lint this shiny plastic battery pack has already managed to pick up … grrr!

Three green LEDs indicate that the battery is fully charged.

There’s no doubt that the iPhone suddenly becomes less svelte when in the holster, but who says it needs to stay in there all the time? Simply slide the iPhone in when you need to top off the battery, or when you’ve run it down so far that the low battery indicator is showing. The Super Charger is ideal for long car rides or cross-country flights, or any other extended activity that would normally mean carrying along a charging cable.

My preferred method for using the Super Charger is to keep it in a gearbag pocket, and then pop the iPhone in throughout the day to top off the charge. I don’t necessarily ever need to make a call on the iPhone while it is in the holster, but the beauty of it is that I could if I wanted to.

notice that the camera is completely unfettered

The front of the iPhone sits flush with the holster’s sides, and there are even cutouts so that you can still enjoy using the speakerphone or listening to movies and music.

I know that there are some who will look at the Super Charger and dismiss it as something they would never carry, simply because it makes the iPhone seem so big when it’s installed, but I’ll say again — they are missing the point. This is the equivalent of carrying 2.5 extra batteries, and since you can’t just pop out the iPhone’s battery and slip in a fresh one, this is the next best thing.

The 3000mAh Super Charger for iPhone 3g and 3GS is available from USB Fever and other retailers.

MSRP: $59.99

What I Like: As much as I like to complain about the glossy, fingerprint loving shiny plstic, it does nicely match the iPhone’s case; 2.5 times the capacity of the iPhone 3GS’s battery; Does not have to stay on iPhone — you can top off your battery with it throughout the day; Uses the original iPod cable; Can use the iPhone when it is in the holster charging

What Needs Improvement: Yep, it makes the iPhone look like a show when installed … it’s big … it’s long. Deal with it.