The Don Rowe Blog
Power Inverters and Microwaves
Inverters are used for all different kinds of purposes, including emergency backup, off-grid power and even simple convenience. When it comes to convenience, there is little more convenient than a microwave oven. Whether you’d like to quickly prepare a warm lunch on a road trip, or heat up the nacho cheese sauce at a tailgater, a power inverter and a microwave could provide some desired convenience just about anywhere. As exciting as this pairing may be though, it is not a simple plug and play scenario. Several factors go into making such a pairing work for your needs.
What you need to know about running a microwave with an inverter:
There are a number of things to consider when running a microwave and we want to consider each one in depth. Let’s break down what needs to be considered before investing both time and money into such an application.
1. What size of an inverter do I need?
At face value it would appear that an 1100 watt microwave would need, well exactly that, 1100 watts to run. However, a microwave’s cooking power does not actually reflect how much it requires to run, and without the actual power requirements you could end up with unexpected overload shutdown on an inverter. Check the back or inside of the microwave and you can find the power consumption. Let’s say the microwave draw is 1550 watts. That is too much draw for a 1500 watt inverter, so a 2000 watt inverter should work nicely.
2. Pure sine wave or modified sine wave?
Typically, a microwave can be powered by both pure sine wave and modified sine wave inverters. However, their performance may differ. Since a pure sine wave inverter’s output is equivalent to utility power, you can expect a microwave to perform normally. Modified sine wave power on the other hand, can cause a range of performance issues. Unfortunately, there is no rule of thumb to determine if any apply to your microwave. Slower cooking, an incorrect clock or timer, and more noise while cooking are a few commonly reported effects of the modified sine wave. Damage to the microwave is rare, but not unheard of. It is important to note that the reduced cooking time is a result of the microwave producing less cooking power on modified sine wave. This reduction in cooking power means the microwave is drawing less power from the batteries. Be mindful of this when changing from modified sine wave to pure sine wave on your pre-existing application as the increased battery draw may cause unexpected issues. I will elaborate more on battery draw next.
3. How much battery power do I need?
One of the most common causes of inverter issues is a lack of battery power, and it is particularly common when running a microwave. It is not recommend to attempt to power a microwave on a single battery system, unless you have a good amount of voltage coming in from an outside source, i.e. alternator, solar, etc. The quicker you discharge a battery, the more internal resistance occurs within the battery, which causes the voltage to drop. This drop in voltage can happen in a matter of seconds on an undersized battery bank, causing an inverter to go into a low voltage shutdown. If you’re going to install this in your vehicle, be sure the motor is running during the microwave’s use. You will also want to ensure that your alternator will compensate for the single battery in the vehicle. A single battery system without incoming charge might work with a modified sine wave inverter since the battery draw is less as a result of the reduced cooking power. In short, use at least two batteries for an isolated battery bank, and if you’re installing this in an average vehicle remember to run the motor during microwave use.
A microwave is a great appliance to add to your RV, off-grid home, boat or tailgater. Adding a microwave is possible in most applications, as long as you take the proper steps to ensure trouble free operation. If you have any additional questions feel free to comment or contact us at DonRowe.com.