Many road warriors carry a spare laptop battery with them so they can extend their work time away from a power source (assuming their laptop uses a removable battery, of course; two of Apple’s recent models do not). But while multiple batteries are useful when working, they present a challenge when charging: You can charge only one at a time inside your laptop, and if you’re actually using your laptop, charging takes longer because the laptop itself grabs a good amount of the power.
This makes a standalone battery charger a useful accessory that ensures you always have a fresh battery on hand. Unfortunately, most chargers I’ve seen are bulky desktop gadgets. FastMac’s TruePower U-Charge, on the other hand, is a portable battery charger that’s about the same size as the current MacBook’s AC adapter and weighs less than six ounces. Two models are available: a 14.4V version that works with batteries for the original iBook, the original iBook 3G, and the Titanium PowerBook G4; and a 10.8V version that works with batteries for G3 PowerBooks (Pismo and Lombard), all other iBooks, Aluminum PowerBook G4s, and all pre-unibody MacBooks and MacBook Pros. (It’s important to use the correct U-Charge model. Because Apple has used the same connectors on most of its laptop batteries for the past decade, both U-Charge versions will fit most batteries; FastMac warns that using the wrong U-Charge model can result in permanent damage to both the battery and the charger.)
Each U-Charge includes two cables: one to connect the charger to any standard AC wall outlet, the other to connect to your laptop battery. The 22-inch battery cable has a connector that slides right into the battery’s terminals. Once connected, a light on the U-Charge indicates charging status—red for charging, green for fully charged. (There are also four “charge indicator” LEDs, but these don’t indicate the current charge level…at least not when charging. More on that below.)
In my testing with batteries for a white MacBook and an original MacBook Pro, the U-Charge worked well, fully charging the batteries; in fact, the U-Charge juiced up those batteries noticeably faster than they charged inside the laptop itself, even if I wasn't using the laptop at the same time. And I appreciated the capability to charge one battery while I was using the other, or to charge two batteries simultaneously—one in the laptop and the other using the U-Charge.
The U-Charge also gives you the option of bringing just the charger when traveling, leaving your laptop’s AC adapter at home to lighten your load. In this scenario, you would use one battery while the other is charging—the U-Charge will fully charge the latter in less time than you can drain the other. You just need to be sure to safe sleep before swapping batteries if you want to avoid having to shut down during the exchange.
On the downside, the U-Charge’s four charge-indicators LEDs are a bit confusing. Instead of indicating the current charge level during charging, they work only when not charging. If you unplug the U-Charge from AC power and then connect the U-Charge to your battery, these lights show you the approximate battery level: 0 (no lights) 25, 50, 75, or 100 (four lights) percent. While this approach works as advertised, it’s a hassle to have to unplug the U-Charge from the power outlet in order to check the currently charging battery's level. I usually ended up just waiting until the battery was fully charged (when the main charging-indicator light turned green).
One other limitation is that neither of the current U-Charge models works with the batteries for the latest (unibody) MacBook and MacBook Pro. A FastMac representative told me the company is currently working on a new version for these models. Although the U-Charge’s battery-connection cable is interchangeable—a design that, in theory, lets you change just the cable to gain compatibility with newer batteries—it’s not yet clear if either of the current U-Charge models will work the latest MacBook and MacBook Pro batteries via a simple cable swap.