One family in New Jersey and another in Massachusetts were the envy of their neighbors when they harnessed their Toyota Prius batteries to power lights and televisions during the dark days after superstorm Sandy.

It's not the first time electricity-starved hybrid owners have resorted to this technique, and it raised the question: How did they do it? There are two ways: either by connecting an inverter to the car's large battery pack, the one that powers the car, or by plugging into the smaller 12-volt battery, which starts the car.

The former technique has a better power payoff. You could, say, run a load of laundry while your neighbors were burning through their candle supplies. We asked Heath Hofmann, associate professor of electrical engineering at the University of Michigan, how to do it:

• Purchase a DC-to-AC inverter with a voltage rating corresponding to your car's battery voltage.
• Hook it up to the battery's two terminals located underneath the cargo hold using electrical wire with the proper current rating.
• Ideally, you'd place a fuse between one of the battery terminals and the wire.
• Then you'd turn on the car and let it run.

This is the technique the savvy Massachusetts family used during the Sandy blackout (see the YouTube video below). They used an 800-watt converter connected via extension cord to an AC strip, a setup that enabled them to keep their refrigerator, cable TV and computer chugging along. Other experts suggest buying a manual transfer switch, used with portable gas-powered generators, to ensure that power is not transferred back to the grid, possibly injuring electrical workers fixing downed lines.

The potential downsides to this approach? Electrocution, if you place your hands on both battery terminals, or a small fireball if a tool such as a wrench falls on the terminals.

"Those could be lethal events," Hofmann told MSN Autos, adding that this method requires experience with high-voltage electrical equipment. "It's definitely not recommended for people who don't know what they're doing."

There's no guarantee your car will cooperate with this technique, because some hybrid control systems prevent such drains on the battery. Currently, there is no known generator "hack" for the Chevrolet Volt or other hybrids, because their battery terminals are not as readily accessible. Here's a big disclaimer: Not a single manufacturer condones the practice or will cover any damage to the battery caused by following this advice.

A safer bet for any hybrid owner is to tap into the smaller battery. This can be done with a store-bought inverter plugged into the car's cigarette-lighter outlet. These inverters are commonly used to charge small electronic devices such as smartphones or laptops.

The reason hybrids are so conducive to this type of charging? You can turn on the car without using the engine, which lets you get as much as 30 hours of power on just a gallon of gas. Even if there's a gas shortage, you're good to go.