Company: Just Mobile
Model: Gum Max
Compatible: All iPads, iPhones, USB iPods
Just Mobile Gum Max Battery for iPad/iPad 2
We've long been fans of Just Mobile's back up battery packs for iPhones and iPods. The original Gum and Gum Pro each earned an A-, while the well-designed Gum Plus got a slightly lower rating but maintained a strong general recommendation. In our experience, the accessories look very nice, and more importantly, do a great job of charging a handheld iOS device. Now Just Mobile has decided to extend the line to the iPad with its mammoth Gum Max ($110). With a 10,400mAh battery, the company claims there's enough juice to give an iPad or iPad 2 a full charge and "still have juice to spare."
In terms of physical dimensions, Gum Max has a volume that’s more than double that of Gum Plus; it’s taller, wider, and longer too. It resembles a small portable hard drive. Instead of five power-indicator LEDs, there are now eight in line with the power button. Just Mobile also replaced the Mini USB inbound charging port with Micro USB, a more ubiquitous standard. Otherwise, the aluminum enclosure is almost identical. Included with the battery pack are a Micro USB cable and a Dock Connector cable—for the incoming charge and outgoing charge, respectively—as well as a carrying bag. That bag is important, as the exterior on this one is just as susceptible to scuffs and scratches as it is on the smaller version. Gum Max was the recipient of the Good Design Award 2011.
While the 10,400mAh battery isn’t the largest we’ve seen—that distinction goes to dreamGEAR’s i.Sound Portable Power Max, with a staggering 16,000 mAh cell—it’s certainly up there. Unlike that unit with its five USB ports though, Gum Plus is designed to charge one device at a time. It’s also important to note that unlike Gum Plus, this larger version does full speed, 2.1A charging. The company is very clear that to refuel it, you’ll need to use either iPad/iPad 2’s 10W USB Power Adapter, or a very recent model of iMac, MacBook Pro, or MacBook Air. It’s so power intensive that when we plugged the battery in to an iMac with two external hard drives attached, a warning popped up on the screen saying that it was drawing too much power and that some of the USB devices have been disabled.
To test Gum Max, we used two iPad 2s; each with the screen off, connected to Wi-Fi, and with no media playing. We began with one of the tablets fully depleted, and moved on to the next one after the first had received a full charge. In each test, Gum Max provided a total charge of 107%—that is, fully charging the first device and then 7% more to the second—in about four and a half hours. While it may seem like such a large battery should be able to provide more juice to the 6,930mAh battery in the iPad 2, the electrical engineering does work out—we’ll spare you the math. For comparison, dreamGEAR’s battery provided 1.5 times the charge with 1.54 times the capacity, so the results are right around where they should be and fall in to line with the expectations set by Just Mobile.
Ultimately, we were very happy with Gum Max. The sharp-looking battery performed just as we expected it to. Compared to i.Sound Portable Power Max, however, Gum Max isn’t as great of a value. For only $20 more, dreamGEAR’s model has a much larger capacity cell and can charge multiple devices at once—in an admittedly larger package. Because of this, Gum Max earns a B rating. We do recommend it, and it is an especially good option for style-conscious users looking to guarantee an extra full charge for their iPad or iPad 2 on the go.