Pure Sine Wave Inverters: Necessary or Overkill?

They're more expensive, but are they worth it?

Most electronic devices work fine without a pure sine wave inverter, but there are some things to think about before making a purchase. You'll want to understand why differences between pure sine wave inverters and modified sine wave inverters can cause problems.

The two main issues 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.

Do You Need a Pure Sine Wave Inverter? 

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

  • Does the device or appliance use a motor?
  • Is the device a delicate piece of medical equipment?
  • Does the device or appliance use a rectifier?
  • Can the 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 may be fine without one.

pure sine wave
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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 result in efficiencies. 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 perhaps not as efficiently, which may lead to excess heat buildup and possible damages.

If you use a CPAP machine, especially one that includes a heated humidifier, you may want to consider 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, 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 for extra peace of mind and to future-proof your installation, you can't go wrong with a pure sine wave inverter. It will work fine even in situations where you don't need one.

However, most electronic devices run well on a modified sine wave. For example, laptop computers, cellphone 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 fine without a pure sine wave inverter.

With many of those devices, you can cut out the middleman and use a DC-to-DC converter that steps the 12V DC from a 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 devices.​

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