The Kensington Mini Battery Pack and Charger mentioned in my previous blog posting is just one of many iPhone battery extender solutions.

Also from Kensington is the Kensington Battery Pack and Charger for iPhone and iPod. This battery pack can charge the iPhone and iPhone 3G, iPod Classics from 4th to 6th generation, and the iPod Nano 3rd generation. It also comes with a mini USB cable to charge other devices too.

Another charger that clips into the bottom of the iPhone is the “Cygnett GroovePower Now Battery Pack for iPods and iPhone“.

There are a number of variations of these chargers. The main advantage with them is that they can be used with an existing case. The disadvantage is that while is use they make the iPhone a bit unwieldy.

Then there is the Mophie Juice Pack for iPhone. When the iPhone is connected to the Juice Pack, the iPhone sits slightly elevated, allowing the microphone and speaker ports to be used. The only problem is the iPhone sheathed in the Juice Pack  will not fit into any of the existing iPhone cases.

That is where the Power Slider by Incase comes in. The Power Slider is both a battery extender and a case from Incase. It does increase the size and weight of the iPhone, but is one complete unit. Here is a review with pictures from Engadget.