One of the big problems with Apple’s smartphone tech is that the iPhone

battery can’t be removed and a replacement inserted as a back up, meaning that if the battery in your new iPhone 4 drains you need to charge it via a power socket or use an extended battery pack.

Well we have such an extended battery pack for the iPhone 4 for your consideration as according to an article over on Engadget by Thomas Ricker, the PowerSpring 4 from Mili can double the life of your iPhone 4 battery due to its 1600mAh Li-Pol battery.

The Mili PowerSprint 4 for the iPhone 4 claims to be the slimmest iPhone 4 battery pack in the world and begins shipping today commanding a price tag of £54.99, which if it doubles the life of your batter life isn’t all that bad a price.

So if you need to extend the battery life of your iPhone 4 because you are frequently out and about and nowhere near a charger, maybe the Mili PowerSpring 4 just might be worth looking at.