A car power inverter allows you to power a normal electrical or electronic device off your car's cigarette lighter. That means you could potentially run a small TV and DVD player on long trips to entertain your kids, charge up your notebooks and cell phones, and even power a hifi or karaoke for an outdoor party. There main type of car power inverter today is the modified sine wave type. This is much cheaper than a true sine wave type, but it means that some electronics devices will not work with it. An additional issue is that newer car power inverters are not made to the same high standard as older devices - older devices almost always produce AC power at 60 Hz, but newer devices produce from 56 Hz to 64 Hz. That means a number of cordless tools, some PowerMac models, some cell phone models, clocks, microwaves, etc will not work off the more popular car power inverters.

You could easily buy a good power inverter for $25 that would meet 70% of your needs, but sometimes you need that extra 30%. This makes buying a car power inverter a task that requires some thought. First, you need to know what electronic or electrical devices you want to run off your car's battery. Then you need to find out how finicky your electronics are concerning their power supply - you need to find out the AC frequencies they need, and whether they need a true sine wave. Then you need to test them with a whole bunch of different power inverters to see which ones work. Also keep in mind that a car power inverter plugged into the cigarette lighter only lets you draw 100 Watts (this will vary with different cars and inverter combinations). Any more than that and you will need to plug it directly to the battery. That means you may need to go to your car mechanic to get it hardwired correctly.

One important point to note when buying a car power inverter is to get one with a cooling fan. This helps to keep the device cool when you use it for an extended period of time. The fan can be noisy, especially in newer luxury cars with good soundproofing, but that is the price you need to pay if you want to use your electronic equipment the whole day long in the car.

A second important point is that most people should only buy car power inverters rated below 500 Watts. Many of those with higher ratings do not plug into the cigarette lighter - they need to be wired directly to the car battery. A more important consideration is that they may suck up so much power that your car battery runs out even when your engine is on. Of course, this is not usually a problem if you only plug in a notebook computer, but it can be a problem if you plug in a large screen TV or a refrigerator (for a camper van or mobile home or during an electrical outage).

The four top makers of car power inverters are:

  • Xantrex
  • Jensen
  • Duracell (most quiet operation, but also most likely to shut down due to overheating)
  • Cobra (better known for inverters over 500 Watts)

Regardless of brand, the power inverters with outputs between 100 Watts and 200 Watts seem to be the most reliable with the fewest complaints. The power inverters rated between 300 Watts and 500 Watts have received complaints that they do not work, and may even damage or burn out the car's electrical system (or at least the cigarette lighter).

So when you choose a car power inverter, keep these points in mind: test the actual unit (not just the demo unit) you want to buy with all the electronics and electrical devices you want to run; you cannot run more than one or two electronic devices off the cigarette lighters of most cars; and choose an inverter with a cooling fan if you intend to use it for long periods of time.