Pure Sine Wave Inverters: Necessary or Overkill?

pure sine wave
Pure sine wave inverters deliver "cleaner" A/C power, but they cost a lot more than modified sine wave inverters.

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Most devices will work just fine without a pure sine wave inverter, but it is a good idea to think about the issue before making a purchase anyway. First, it’s important to understand why the differences between pure sine wave inverters and modified sine wave inverters can cause problems.

The two main issues at hand are efficiency and undesired interference from the additional harmonics present in a modified sine wave. That means that a pure sine wave inverter is good at two things: efficiently powering devices that use the alternating current input without rectifying it first, and powering devices like radios that can suffer from interference.

Some useful questions to ask yourself in order to determine if you need a pure sine wave inverter include:

  • Does my device or appliance use a motor?
  • Is my device a delicate piece of medical equipment?
  • Does my device or appliance use a rectifier?
  • Can my device be powered by a DC adapter?

If you answered yes to either of the first two questions, you may need a pure sine wave inverter. If you answered yes to either of the second questions, then you’ll probably be fine without one.

When a Pure Sine Wave Inverter Is Necessary

While a modified sine wave inverter will get the job done in almost every circumstance, there are some cases where it may cause damage or just not be very efficient. The primary category of devices that run more efficiently with a pure sine wave inverter is electronics that use AC motors, like refrigerators, compressors, and microwave ovens. They’ll still work in most cases, but they may not work as efficiently, which may lead to excess heat buildup and the potential for associated damages.

If you use a CPAP machine, especially one that includes a heated humidifier, then you’ll probably want to go with a pure sine wave inverter to avoid damaging the unit. It’s always a good idea to check the recommendations of the manufacturer, but most CPAP manufacturers recommend going with a pure sine wave inverter.

When a Pure Sine Wave Inverter Isn’t Necessary

If you have electronic devices that use rectifiers to convert AC to DC, then you probably don’t need a pure sine wave inverter. Don't be mistaken, a pure sine wave inverter will still work just fine with these devices. If you have the money, and you don’t mind spending more than you have to just for extra peace of mind and to future-proof your installation, then you can’t go wrong with a pure sine wave inverter. It will work just fine even in situations where you don’t really need one.

However, most electronic devices run just fine on a modified sine wave. For example, laptop computers, cell phone chargers, and all other equipment that uses a rectifier or AC/DC adapter to take an AC input and output DC to the device will typically work just fine without a pure sine wave inverter.

Of course, with a lot of those devices, you can just cut out the middleman and use a DC to DC converter that steps the 12V DC from your truck’s electrical system either up or down without first converting it to AC before converting it back to DC. This is the more efficient route to go, so it might be worth looking into if a 12V adapter is available for any of your electronic device.​