Using a Car Power Inverter As a Generator

Automobile inverters work in a pinch, but they're no subsitute for generators

Silhouette Skyscrapers Against Orange Sky
Ramzi Rizk / EyeEm / Getty Images

Although nothing precludes you from running electronics inside your house off a car power inverter, it probably isn’t a good idea. If the engine isn’t running at the time, you’ll find that the car battery will die pretty fast. And if the engine is running, you’ll find that using your car as a makeshift generator is typically going to be less efficient—and less effective—than just buying a real generator.

If you have another heat source, like a wood-burning stove, you’re better off using that until the power comes back on. And if the situation is really dire enough that you have to use your car inverter to run heaters in your home, you’re probably going to be better off using that gas to get yourself to an emergency shelter or warming station.

Running Home Electronics With a Car Power Inverter

Car power inverters are great, but they’re designed to be used when the engine is running. When the engine isn’t running, the inverter draws stored power from the battery rather than relying on the power generation of the alternator. Since car batteries have a finite amount of power storage, using an inverter when the engine is off drains a battery quickly. In fact, a typical car battery will have less than two hours of reserve capacity, which is defined as the amount of time that the battery can power a 20A load before the voltage drops below 10.5V. Letting the charge drop that low, or lower, isn't very good for the longevity of a battery, which is why it's bad to let batteries die.​

If you plug an extension cord into the inverter in your car and use it to run electronics in your house with the engine off, you may find that you can’t start your car later on. For this reason, recreational vehicles and other automobiles that have to deliver a lot of power when the engine isn’t running typically have one or more deep-cycle batteries devoted to that purpose.

What If the Engine Is Running?

If you leave the engine running, and you have an appropriate outdoor extension cord handy, then it’s perfectly safe to run electronics in your home with a car power inverter. However, there are a handful of potential problems to consider. First, verify that your inverter provides enough power for the intended load. If you bought an inverter to provide power for a DVD player, game system, or another small electronic device, it may not be able to handle the power needs of a space heater or whatever other electronics you want to plug into it.

If you leave your car running unattended, check it regularly to assess the fuel level.

It's more efficient to run a generator than to use your car engine and an inverter. A large generator can even power appliances like your fridge and freezer, several space heaters, and even an air-conditioning unit if your power goes out during the summer. The same isn’t true for most car power inverters.

If you run your car to use your inverter a makeshift generator during a power outage, the exhaust fumes are hazardous. It's never a good idea to run a car inside a closed garage because of the potential buildup of carbon monoxide and subsequent danger of carbon monoxide poisoning, and while you should be safe if your car is parked outside, you should still take the same precautions that you would with a generator, like making sure that the exhaust fumes are directed away from your house.