Let’s be honest: the battery life of the iPhone 4 and iPhone 4S can kinda suck. Spyder’s PowerShadow i4 Battery Case & Charge/Sync Dock is designed to make it suck a whole lot less. Made out of black polycarbonate, the i4 boasts a built-in 2000mAh battery pack that, according to our testing, can charge a fully drained iPhone 4S to between 75 to 80 percent of its full capacity.

Like all battery cases, the i4 will increase the size and weight of your svelte Cupertino-designed handset significantly. But for power users who can’t make it through their day without using up every last bit of juice their iPhone can muster, the extra heft is a reasonable compromise given the amount of extra power the case brings to the party. The case allows for access to the phone’s camera and its volume and power buttons through a number of recessed holes cut into the sides and back. The case’s battery and the iPhone itself can be charged and synced via micro USB or by using the case’s included charging dock: a nice touch that differentiates the i4 from other iPhone battery cases. To draw power from the i4 internal battery, just push a button on the back of the case. When you see the i4’s indicator lights come on, you’re in business. 

But while there’s a lot to like about the i4, it’s not all wine and roses. Let’s start with those LED indicator lights: as long as the iPhone’s drawing power from the i4, they never turn off. It’s a minor quibble, but annoying. It’s also worth mentioning that when the i4 was charging our handset, the case became hot enough that we didn’t feel comfortable putting it in a pocket. Perhaps most importantly, while the i4’s 2.6-ounce weight added considerable heft to our iPhone, the case’s construction felt kind of flimsy. We understand that what Spyder’s given us here is a battery and charging solution, but we can’t see any reason why these benefits can’t come bundled in a modicum of protection.

The bottom line. PowerShadow i4’s perks and shortcomings balance out in such a way so as to make it a good, but not great way to provide your iPhone with the extra power you require to make it through the day.