If you're considering the US$129.99 iSound Portable Power Max (http://macte.ch/K38or) back-up battery, ask yourself two questions:
Am I regularly running out of juice on my iOS devices?
Do I need to charge more than one such device while I'm on the road?
If you answered yes to one of these questions, you might need an Portable Power Max. If you answered yes to both, you definitely need one.
The back-up, 16,000 mAh battery provides up to 480 hours of power and sports five USB ports that allow you to charge and power several USB powered devices simultaneously. It also boasts a dual USB cable with both a mini and a micro-USB cable so you don’t need a plethora of cables to be able to use it.
Five LED status indicators on the front of the device let you know how much charge remains. Plus, there's a soft carrying bag and a built-in flashlight to help you connect in the dark. No, really. A flashlight, which you can turn on and off.
The iSound Portable Power Max can juice up a completely plooped out iPad 2 in just over three hours. Plus, it has a minimalist black-and-silver design that's relatively attractive.
The Portable Power Max is, well, portable (it fits into a briefcase, suitcase or auto glove compartment), but it ain't light (it's 14 ounches). It's a heavy power supply -- and flashlight!
It takes about eight hours to charge and recharge. Also, I did notice a bit of a hiccup when I attached my iPad, iPhone and my wife's iPod touch all at the same time. Evidently, it couldn't handle the power demands of all three at once so alternately turned the power to all three on and off to all three. I didn't notice this problem with two iOS devices and a less power hungry gadget (a "normal" Samsung cell phone, for instance) connected simultaneously.
Also, a built-in fold out wall plug to eliminate the power adapter would be nice. Despite these gripes, if you need lots of extra juice to take with you for your iOS devices and don't mind a little extra heft, the Portable Power Max will take care of you.
And did I mention it's also a flashlight?
-- Dennis Sellers