Three features make the HyperMac batteries especially appealing. First, each battery can actually your laptop's internal battery--not just provide operating power--during use. Second, the batteries support Apple's dual-voltage power system, automatically switching as needed. (MacBook and MacBook Pro models normally use 14.5V of power, but draw 18.5V during demanding tasks.) Third, each battery also provides a 5V/1A USB-power port for charging or powering your iPhone, iPod, or other USB-powered devices at the same time as your laptop.

As a bonus, all but the MBP-060 model include, at no extra charge, the company's $150 . This 3.5-ounce car charger plugs into a car's accessory ("cigarette-lighter") jack, using the same MagSafe cable as the HyperMac battery to provide power to your laptop--in other words, the charger works independent of the HyperMac battery. Sanho claims the Car Charger is safer and more efficient than using a power inverter and provides a more-stable power source. Like the HyperMac batteries, it also supports dual voltage modes.

Given that you can charge your MacBook while the HyperMac battery itself is charging, Sanho's combination of an AC adapter, a DC charger, and a battery in a single package means you've got power solutions at home, in the car, or when away from any outlets.

On the other hand, one feature I'd like to see is the capability to the HyperMac batteries via USB, which would let you charge them from a plugged-in laptop or--even better--a . And an or for in-flight power and some sort of international power adapter or plug set would be useful for globe-trotting travelers.