Your car battery can be a great source of backup power, but you can only tap into it with a 12-volt inverter, which converts 12-volt DC power to the 110-120 volt AC power used in homes. You can find an inverter rated for whatever power requirement you're likely to have. The rating is displayed in watts and you'll need to match it to the devices you intend to run to make sure the inverter can handle the loads.
Xantrex says its Micro Inverter 175 is the smallest 175-watt inverter you can buy. The 175 is 5 inches long, 2.5 inches wide and 1.5 inches deep. It plugs directly into a cigarette lighter without using a cord, cutting down on clutter while increasing convenience and durability. The Micro Inverter 175 has a single AC outlet and a green LED glows to indicate power is available. It automatically shuts down if your battery runs low, the inverter overheats or its internal fuse blows. A built-in cooling fan provides additional protection for the sensitive electronics. The Micro Inverter 175 comes with a one-year warranty and retails for about $45 (as of November 2010).
The CPI 480 lacks the portability of the Micro Inverter 175 but delivers plenty of bang for the buck. The 400-watt Cobra inverter can connect to a cigarette lighter or directly to a battery. It has two AC outputs and a 5-volt USB (universal serial bus) receptacle. You can run two household appliances with a cell phone, media player or laptop if you stay within the inverter's load limits. The CPI 480 can handle up to 800 watts of peak power but automatically shuts down if the polarity is reversed, the inverter gets too hot or the battery voltage gets low. It also has a fuse to protect it from surges and overloads and an internal fan to keep temperatures down. Cobra inverters carry a two-year warranty and the CPI 480 is available for about $25 (as of November 2010).
According to eco20-20.com, Exeltech's XP 1100-12 delivers some of the cleanest power you can get in a 12-volt inverter. It has a well-regulated, true sine wave output ideal for computers and other sensitive electronics. It's also rugged and flexible enough to use in marine and military applications. When the XP 1100-12 is on but no devices are running, a low-idle current feature minimizes drain on your battery. The XP 1100-12 delivers 1,100 watts of continuous power with a peak output of 2,200 watts. It has protections overheating, over and under voltages and short circuits. Exeltech offers a full one-year warranty on the XP 1100-12, and it retails for about $718 (as of November 2010).
