Modern mobile computers give us an amazing amount of flexibility in our ability to work and play, but those who use Post-PC devices also know we can still be brought down by another ancient concept: a lack of electrical outlets to charge the devices. Look around at the airport, restaurant, or convention center, and you’ll see them huddled around one or two plugs, waiting. But companies like Just Mobile have sprung to the rescue with portable chargers like the Gum Max Duo, which packs two ports and enough juice to charge an iPhone and iPad simultaneously.
I was a fan of the Gum battery, which was small enough to be carried in a pocket but lacked the ability to fully charge an iPhone 5. The Gum Max Duo is substantially larger (and weighs more than half a pound), but fits easy into a purse or backpack, making it practical to charge while on the go. It has two USB ports, one rated at 1 A for mobile phones, and the other at 2.4 A for the iPad. Both ports are labeled with their amperage (and intended devices), though the white lettering on the silver case can be a bit hard to decipher quickly. Like the standard Gum battery, the Max Duo charges using a USB to micro-USB cable (included) and cannot be used as a pass-through charger (that is, you shouldn’t attempt to charge an iPad while the battery is charging).
Just Mobile estimates that you can get an extra 7 hours of iPad battery life out of the battery, and I found that to be accurate, although more often I was using it to double-charge an iPhone 5 and original iPad at the same time while on the road. I never let the devices go fully dead, but the Max Duo was consistently able to recharge both of them while still holding on to one last bit of power in case I needed an emergency last-minute boost. In addition, it can detect when the devices to which it’s connected are fully charged and will shut itself off, saving power for a later time. The Max Duo indicates its charge using seven small green LEDs which are easy to see even if you use one of the rubber cases, which come in black (included), red, yellow, and blue.
For frequent travelers, conventioneers, or any situation where you need to stay connected without being tethered to a wall outlet, the Gum Max Duo is a great solution for extending your battery life. You’ll trade pocketability for a lot more power, and if you’re carrying two or more devices that can be charged via USB, you probably have a bag to store the battery in already.
Category: USB battery backup
Developer: Just Mobile
System Requirements: Device that can be charged via USB
Review Computer: iPhone 5, original iPad
Availability: Out now