12 Volt Microwave: What’s Actually Available
This page used to sell the WaveBox, a portable microwave that ran on household power or straight from a 12- or 24-volt battery. It has been discontinued for years, and nothing has really replaced it. Today almost everything sold as a “12 volt microwave” or “portable microwave” is a heated lunch box, not a microwave at all. If you want to heat food on 12 volts, there are three honest options.
Why a car power socket can’t run a microwave
The WaveBox showed the problem clearly. Wired straight to the battery, it cooked at 660 watts — the same as on household power. Plugged into a 20-amp vehicle power socket, it managed only 235 watts: enough to reheat a cup of coffee, not enough to pop popcorn. A microwave needs far more current than a power socket can deliver.
Option 1: an ordinary microwave on an inverter
This is the only way to get real microwave cooking from a 12-volt battery, and it is what most truckers and RV owners do: a small household microwave, powered by an inverter wired to the battery.
- Size the inverter on the input watts, not the cooking watts. A microwave’s label lists both, and input is typically about one and a half times the cooking power — so a 700-watt microwave draws roughly 1,000 to 1,200 watts. A 1,500-watt inverter is the minimum; 2,000 watts leaves room for anything else running at the same time. The inverter calculator works it out from your microwave’s label.
- Choose pure sine wave. Microwaves will run on a modified sine wave inverter, but they tend to cook more slowly, run hotter and hum, and some digital controls misbehave.
- Wire it to the battery, not the power socket. At 12 volts a microwave pulls over 100 amps, which needs heavy cable and a proper fuse — the calculator gives you the cable size. Run the engine while you cook; a microwave flattens a battery quickly.
- 24-volt trucks draw half the current for the same microwave. Use a 24-volt inverter.
Inverters that will run a microwave
More choices: 1,500-watt inverters, 2,000-watt inverters and 24-volt inverters. Not sure which 1,500-watt model? 1500 Watt Inverters Compared puts six side by side.
Option 2: 12-volt ovens and slow cookers
These plug into the power socket and heat food with an element rather than microwaves, so they draw little enough current for a vehicle socket. They work like a small oven or slow cooker, not a microwave: plan on tens of minutes, not seconds.
Cook on 12 volts from the power socket
More in 12-volt cooking and kitchen.
Option 3: a used WaveBox
WaveBox microwaves still turn up second-hand. They ran on household power or on 12 or 24 volts DC, and the cooking power figures above apply. There are no parts or service for them any more, so look for one described as tested and working. A live eBay search for WaveBox microwaves shows what is available now.
Common questions
Can I plug a microwave into my car’s power socket?
No. Even a small microwave draws over 100 amps at 12 volts, and a vehicle power socket is fused at 15 to 20 amps. The WaveBox, which was built to run from a socket, could only manage about a third of its cooking power that way.
What size inverter do I need for a microwave?
Check the input watts on the microwave’s label — usually about one and a half times the cooking power. A 1,500-watt pure sine wave inverter covers most compact microwaves, and 2,000 watts gives headroom. Our inverter calculator sizes it, along with the battery cable.
Will a modified sine wave inverter run a microwave?
Usually, but less well. On modified sine wave power a microwave tends to cook more slowly, run hotter and hum, and some digital controls misbehave. Pure sine wave is the better choice.
Is a portable lunch box oven a microwave?
No. Products sold as 12-volt or portable microwaves are almost always heated lunch boxes with a heating element of around 100 to 150 watts. They work well for reheating food on the road, but they take tens of minutes rather than seconds.
Not sure what your setup can run? Send us the details — we’ll do the research, see what we can find, and give you an answer as quickly as we can.