It’s magic! You can take 12 volts DC from a battery and turn it into 120 volts AC ready to power all your devices. In fact, the more you know about how electricity works, the more impressive that magic becomes.
The magic all happens in a device called an inverter. They come in different sizes – from something that might just power a small stereo all the way up to something that can run a whole house worth of devices.
But wait: This doesn’t mean you can power your 60″ plasma TV, your popcorn-making microwave, and your 500 Watt stereo system from your starter battery while you sit in front of an electric space heater. Or, if you tried, it would be a short movie night and your van wouldn’t start the next morning.
I’ve talked before about how 12 volts is less “pressure” than 120 volts. Your 120 volt appliances will want a lot more energy than the 12 volt starter battery is able to give. That’s why we added a dedicated battery for running things in the van that is around twelve times the capacity of a regular starter battery.
Not that we’ll be putting a massive TV, sound system, or electric heater in the van. We have other forms of entertainment, and we’ll be using a diesel heater. But the point remains: inverters are awesome.
We will be using a Victron Multiplus Compact, which is a pure sine wave inverter/charger. Pure sine wave output is important because some AC equipment gets upset if the alternating current isn’t as smooth as it likes. Microwaves and things with motors in them are especially sulky with modified sine wave or square wave inverters.
In this picture you can see the “naked” inverter attached to the battery box. Next to it is the slightly smaller solar charge controller.
The Victron we’ve chosen will power 2kW of equipment at once. That’s just about enough to run a small 700W microwave and a 1000W induction ring at the same time. The math sounds weird – how come it takes 2kW (2000 Watts) to run a 700W and a 1000W device? The thing is, the 700W rating is for the microwave’s output – how much cooking power it produces. It takes an extra 300W to make that much cooking power because the innards of the microwave need power to operate.
Pretty much everything else in the van’s electrical system is sized around this 700W microwave capacity. The inverter has to be big enough to power the microwave and induction ring. The battery has to be big enough to power the inverter for long enough to let us cook for a certain number of days. The solar system has to be big enough to recharge the battery. And so it goes.