One of the key advantages of battery backup power is the ability to "start up" within milliseconds. This means that computers and other electronic equipment won't shut down or reset when the grid fails. By contrast, even the most sophisticated gas generators with automatic startup can take 10 to 20 seconds to get things running again.
The most reliable backup source for computers is a UPS (uninterrupted power source), a special battery unit that remains plugged in to your equipment at all times. A UPS can be used in conjunction with standard battery and generator backup systems.