Buying guide for best power inverters
A good power inverter offers great convenience, and it needn't cost the earth. Does that mean you can just opt for the cheapest power inverter available, or should you invest a little more for added functionality and higher output?
BestReviews was created to help you answer tough buyer questions. If you're ready to buy, our recommended power inverters above have passed our stringent evaluation procedures and offer a terrific range of affordable solutions.
If you'd like to know more about what separates the best power inverters from the rest, peruse our handy guide.
Who needs a power inverter?
Anyone on the move – in a car, truck, RV, or motorboat – can take advantage of a power inverter. That’s because each of these vehicles has a battery (usually 12 volts) that is useful for running a laptop, DVD player, or even a refrigerator. But the vehicle battery is direct current (DC), and all those devices run off of alternating current (AC). That’s where the power inverter comes in.
A power inverter has one job: to convert DC to AC. Buy one small box that plugs into your cigarette lighter socket or attaches directly to your battery, and you can plug in all those devices and charge your smartphone, run power tools, or set up lights at your campsite.
Yes, there are limits on the amount of power an inverter can provide. But in general, if the device is light enough to carry around, then you can run it from your vehicle with a power inverter.
Power inverter vs. portable generator
Although larger inverters do exist, this article focuses on 12-volt power inverters that work off of 12-volt batteries. There is a limit to the power they can provide.
A power inverter doesn't generate electricity. It takes the battery's DC output and changes it to AC. You keep the power inverter right in the vehicle with you. Left unattended, some power inverters can drain the battery. Most have an alarm that warns you when the battery is getting low or an automatic sensor that detects low power and shuts things down. To restore power, just run your motor. Your vehicle will recharge its battery after a while.
A portable generator creates its own electricity. But you must fill it with gas and run a motor, which can be noisy. A portable generator, even a small one, must stay outside.
If you're going camping and looking for peace and quiet, a power inverter beats a generator every time!
In our research, we look for the most reliable power inverters that won’t damage sensitive electronics.
Maximum total output is one of the first things we look for when assembling a shortlist of today’s best power inverters.
We appreciate compact and highly portable power inverters that are great for powering small electronics while maintaining efficiency.
We give extra consideration to power inverters with low battery alarms that help prevent you from draining your vehicle’s battery too much to start it back up.
We look for the best power inverters with simple AC outlets in addition to top-quality models with USB ports that are versatile and complex.
One of our goals is to find the most effective DC-to-AC power inverters for charging common electronics, like laptops and smartphones.
For consumers who need to power demanding electronics and appliances, we search for the best premium power inverters that produce a pure sine wave safe for high-powered equipment.
Integrated voltage monitoring and overheating sensors are some of the safety features we look for when reviewing the top power inverters.
We look for power inverters that are free from major errors and don’t make too much noise.
We consider power inverters with cigarette lighter plugs as well as some with 12V battery clips. The latter are helpful in case your vehicle can’t push enough wattage through the cigarette lighter and you need a direct battery connection.
Power inverter features
There are two main factors to consider when choosing a power inverter: output and connectivity.
Output: Output is measured in watts, and on inverters, it runs from about 150 watts to a maximum of 10,000 watts.
Connectivity: All the power in the world won’t do you any good if you can't plug in your devices. Low-power inverters typically have a single AC (household) socket and one or two USB ports. High-power inverters might have four AC sockets and four USB ports. But not all USB ports are the same. On cheaper power inverters, the supply to USB ports can be as low as one amp. On more powerful models, it can be greater than two amps. That can make a big difference in charging times.
It's vital you have enough connectivity for your demands, but it must be balanced with your power requirements. There's no point in having four AC sockets on a 150-watt inverter. There isn’t enough output to power that number of devices.
Is more wattage better?
You may be wondering if it would be to your advantage to buy a high-wattage power inverter. Keep these tips in mind when shopping.
A power inverter with a higher wattage costs more. A 10,000-watt inverter is very expensive.
Higher wattage drains the battery faster. If you use a 300-watt power inverter, your battery is going to drain approximately twice as fast as it would if you were using a 150-watt power inverter. If you want to run a laptop (about 300 watts) and have the kids watch a DVD (about 200 watts), then you need a bigger power inverter. And you would need a massive, commercial-vehicle battery to support a 10,000-watt inverter.
Finding the right wattage for you
So how do you know what wattage is right for you? Add up the watts used by all the devices you think you'll run at the same time (the watts they consume should be marked on them), then buy the smallest inverter that can comfortably power them. If all you want to do is recharge your smartphone (about 20 watts) and run your tablet (about 120 watts), a 150-watt power inverter should do the job.
MSW inverters vs. PSW inverters
There are two types of power inverters. One generates a pure sine wave (PSW) and the other generates a modified sine wave (MSW). Some electrical devices work fine with one but not the other, so it’s important to get the right power inverter for your needs.
In low-power environments (smartphones, tablets, laptops), it's not a significant problem. If you're thinking of investing in a high-power inverter and running major appliances, it's always safest to check with the manufacturer of the appliance to see if it will run on MSW or requires PSW.
PSW: When displayed on an oscilloscope, AC current forms a pure sine wave, also called a true sine wave. It looks like a series of smooth arcs. Some battery chargers for cordless power tools must always be used with PSW inverters.
- MSW: This sine wave looks more like piles of square blocks. The power comes on, rises instantly, stays at the same level, then drops drastically. This can have a detrimental effect on some devices, and in rare cases, it can shorten the life of the device. A device with an internal motor, such as a refrigerator or microwave, may not work at all. Certain fluorescent bulbs don't work with this type of power inverter. It's much easier to turn DC into MSW than PSW. MSW inverters are cheaper. They are also kinder to your battery, using power more efficiently.
Other considerations
Look for a sensor for overheating. Inverters can get very hot if used for long periods of time. Choose one that can sense when it’s overheating and turn itself off.
Check the dimensions. More power means a bigger unit. If space is a consideration, be sure to check the unit’s physical dimensions. Don't forget that you need room for proper ventilation, too.
Look for safety features. Some inverters can sense overloads, incorrect voltage supply, and short circuits. Such safety features protect not just your car and inverter but also your devices.
"Some inverters continue to draw power after you turn off the vehicle’s ignition. An automatic shut-off system will keep your inverter from completely draining the battery."
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Choose a long enough cable. Even if you only use it inside your car from the cigarette lighter port, it's nice to have enough cable.
Choose a quiet fan. A fan is required to keep the power inverter cool. A quiet one is always a bonus.
Look for a metal casing. Metal is more likely to protect your inverter from inevitable bumps and knocks.
- Go by the numbers, not the images. Beware of “creative” photography in ads. Some manufacturers might picture multiple gadgets in the same photo as a low-output inverter, suggesting that all those devices can be used at the same time. Check the output figures to see if that's really the case.
For your safety
Keep your power inverter away from direct sunlight and any heating vents in your vehicle.
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Power inverter prices
Under $20: This will buy you a cheap inverter with a couple of USB outlets and a single AC outlet (household socket). If you want the facility to run a couple of gadgets from your car, RV, or boat, it's an efficient, low-cost solution.
$20 to $30: These units will have two USB ports, two AC ports, and between 300 and 500 watts.
About $80: Power inverters in this price range have similar connectivity to the $30 models, but they have around 1,000 watts.
About $250: Power inverters that cost this much are usually 2,000-watt models. Few, if any, power inverters have more than four AC outlets. Most inverters would struggle to provide sufficient power to drive four devices at once. They would also drain the battery quickly.
- $450 to $1,000: These are commercial vehicle models of 5,000 to 10,000 watts that need to be permanently installed.
Tips
Portability is one big benefit of small inverters. If you travel a lot, it might be worth having one permanently installed in your vehicle. It's not a complicated job, and instructions are readily available online. If in doubt, consult an automobile electrician.
If your device has a separate charger, always plug that into the inverter rather than trying to charge it by plugging the device into the inverter.
Many AC devices demand more power to start than they use when they're running. A 500-watt drill, for example, might need 1,000 watts to start, even if only for a second or two. It's important to check whether your devices have this demand (it's called “surge” or “peak”). With something as small as a portable phone, there's not enough surge to make a difference. However, a 1,000-watt refrigerator will likely require at least 1,500 watts to start, so your inverter would need that capacity.
FAQ
Q. Can I use a power inverter instead of a portable generator for my RV?
A. It's a question of how much power you need and how it's produced. An inverter takes DC power from your RV battery and converts it to AC to run the types of devices you would normally plug in at home. Unless you're running the motor to recharge the battery, an inverter is a constant drain.
A portable generator creates its own electricity. You must fill it with gas, so it has to stay outside, but in effect, it makes electricity for you. A good generator can supply electricity for hours at a time.
The most powerful inverters on the consumer market run about 2,000 watts, maximum. There are portable generators that can supply several times that. Commercial vehicle inverters can be more powerful, but they are specialist devices.
Q. How do I know what size inverter to buy?
A. If you want a convenient gadget for charging your cell phone or tablet, a relatively small inverter (150 watts) would do the job. The more you want to do, the more power you need. A laptop, for example, requires about 300 watts.
Most people who just want to run a couple of gadgets while traveling will be fine with inverters around 500 watts or less. However, if you have larger demands, there are plenty of choices.
Look at a power inverter as a compact, convenient, temporary charging/power device for short-term use because eventually, it will drain the vehicle battery.
Q. Why do some inverters have a cigarette lighter plug while others have battery clips?
A. It has to do with the amount of power your vehicle will transmit to the cigarette lighter port. It can be under 200 watts, and the maximum is about 400 watts. If you go above that, you might blow a fuse. High-power inverters have clips to connect directly to the battery, thus avoiding the problem.
