Mophie Juice Pack Plus iPhone case with battery charger

The Mophie Juice Pack Plus is a dual-action case: it protects your iPhone 4 from shocks and being dropped, but it also acts as a charger for when the phone's internal battery runs down. And as iPhone owners know, that happens a lot.

The Juice Pack Plus is the new model, specifically shaped for the iPhone 4, but owners of other Apple models and the iPad and iPod Touch can use other cases from the same manufacturer.

This one fits snugly around the phone's shape, and provides a hard plastic shell. It was pleasant to the touch, but we found it far too large. It nearly doubles the depth of the phone and adds a little to its height, though not much to the width.

That's because the back of the case conceals a large battery pack with a micro-USB socket at one corner for charging. It includes a cable which can be plugged into the iPhone's own mains charger or a computer. It took a long time to charge – over five hours in our tests – which made it more time-consuming than charging the phone itself.

However, there is no doubt of the Juice Pack Plus's efficacy. Although the iPhone 4's battery can last a full day, we have often found that if we are out and about and using it a lot, it's dead before the evening. With the Mophie case attached, recharging was a simple matter of flicking a tiny recessed switch at one corner of the case and it was good to go again.

The price is high, but not enormously so given the reassurance an extra battery gives (of course, the phone's own battery should last longer, but that's a separate issue). Our only qualm is that the case is far too large, making it uncomfortable to keep in a pocket and spoiling the clean lines of the phone.