Portable Battery Shootout: The Zagg Sparq Versus The Dark Energy Reservoir

In our increasingly mobile-based world, it can be tricky to keep your device charged up during the day. Thankfully there are gadgets for charging your gadgets, and we've spent some time with two of the more notable ones.

First up is the Zagg Sparq 3100. It plugs into a standard outlet to charge up (the prongs are built right into the back and flip down when not in use), then you throw it in your bag and forget about until you need it. It has a single USB port for charging on the bottom. Blue LEDs across the top give you an indication of how much juice is left. Zagg says that you can fully charge the Sparq once and it will give your iPhone a full charge twice, and my testing confirms this.

On to the Dark Energy Reservoir. It's a sleek black design that's about the same thickness and width as an iPhone, but a bit taller. The Reservoir charges via USB - if you want to use a wall outlet, you use the included adapter. As for your devices needing a charge, there are two USB ports along the bottom for juicing up two things at once. It had no problem charging my iPhone twice, and the marketing material says it can do so up to 4.9 times.

There are plenty of portable batteries like these to choose from, but between these two, I found myself preferring the Sparq over the Reservoir. It was a function of price, really - Zagg's product is $69.99 and the Reservoir is currently $129, down from $179. While the Reservoir can certainly keep you on the go for longer, I don't consider the added cost to be worth it.

The Sparq's self-containedness is awesome. There are no cords or adapters required to charge it, just the cable from the Sparq to your dead-but-not-for-long phone.