MiLi Power Spring 4 full review

Experts in the field of the iPhone battery/case hybrid, MiLi has updated its Power Spring offering to now work with the iPhone 4. The Power Spring 4 is an attractive unit that fits the new iPhone perfectly and offers a good battery boost too.

As an update to the Power Spring for the iPhone 3G and 3GS, the Power Spring 4 packs a higher capacity battery – up to 1,600 mAh from 1,200 mAh. The iPhone 4’s battery performs better than the 3GS’s battery anyway, so with the Power Spring 4 you should get good usage out of the gadget before you have to charge it conventionally.

We ran our iPhone 4’s battery down completely, then turned on the Power Spring 4. Playing video, this let it run for an extra six hours, which is a hefty boost. If you’re not using the phone for video, games or some other power-hungry use, you should get a lot of extra life out of it.

The Power Spring 4 doesn’t turn on by itself, you just press the power button when you want to start charging up your iPhone. This lets you stay in control of your power, boosting it just when you need it.

The case almost doubles the thickness of your iPhone 4 when you plug it in, but it doesn’t add too much weight. It’s well designed, too, sitting perfectly flush, so the product looks like it’s part of the phone itself. There’s a massive cut-out for the camera and flash so that the thick case doesn’t obscure the lens. One issue, however, is that the shiny black plastic picks up fingerprints badly.

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