Pure Sine Wave Inverters are handy devices that can really take camping trips, life on the road, or vanlife to the next level. When connected to a 12v or 24v deep cycle auxiliary battery - the type of secondary battery generally used in your car or van - an inverter will convert this power to a 240v AC power, the same kind of power running through the wires in your house.
This then allows you to plug in and power any device or appliance you would use at home without having to find a 12 or 24-volt alternative. Coffee machines, laptops, televisions, kettles, power tools and more are all possible with the right sized inverter.
How much power do my devices use?
To figure out what size inverter you’ll need, you first need to take a step back and ask yourself what devices you’re wanting to power while off grid. Like any power system, what size inverter you’ll need will depend on how much power these devices consume.
This power consumption information is usually included on the electronic devices themselves. Though the general power draw can be estimated, it pays to check your devices and make a list of their power consumption before looking into inverter sizes.
Though power draw can be estimated it always pays to check the actual draw on your appliance
Another thing to note is that the power needed to start most appliances can exceed the listed power consumption. Any appliance with a motor, pump or compressor will generally have a higher peak power draw than is listed on the device. This is important as your inverter will need to be able to handle this peak demand.
A good rule of thumb to remember when choosing an inverter is that you need to add 20% on top of your base power requirements and select an inverter that meets this capacity. This gives you some breathing room meaning that you’ll have plenty of power in case you decide to add or upgrade appliances in the future.
How do I work out what size inverter I need?
To work out what size inverter you need, it’s really important to have a good understanding of the power requirements in your setup, because deciding on an inverter size is a little more involved than just matching a 1000W microwave with an 1000W inverter.
Charging your devices is made easy with a Pure Sine Wave Inverter
If you were wanting to run a 1000W microwave, it’s recommended to give yourself a bit of security by choosing a 1500W or even 2000W inverter instead. This allows for the microwave to comfortably output 1000W while running without fear of overloading or damaging the inverter.
Choosing a bigger inverter will also mean that you can run multiple appliances at once, rather than being limited to only running one appliance at any given time. Though, if you are planning to run multiple devices together, you will need to remember to add up the power ratings of these appliances to make sure they do not exceed the inverter rating. Our guide to finding the right inverter is a good place to start when deciding on the right size for your setup.
Will my battery power my inverter?
So, you’ve figured out what size inverter you’ll need to power your life on the road, now you’ll need to work out what size battery you’ll need to power the inverter. An easy rule to remember when choosing a battery is that every 100Ah of battery will power a 1000W inverter. Though, the battery will need to be sized based on not only the power required by the 240V equipment but also on how long you will want to run the equipment (e.g. running a piece of equipment for 2 hours will consume twice as much of battery’s Ah capacity as running it for 1 hour).
For example, a 100Ah lithium battery will power a 1000W inverter which is perfect for running laptops, televisions, blenders, power tools, and phone or camera chargers. A 1000W inverter is often the ideal size for most simple setups. Though if you were planning to run this 1000W inverter setup intensively for longer than 10-15 minutes at a time a bigger battery bank would be required to ensure you weren’t depleting the battery beyond its capabilities.
Making sure you have the right size inverter means blenders will run with ease
If you were looking to go bigger, a 300 - 320Ah battery would easily run a 3000W inverter. These bigger setups are often more suited any setup looking to run any of the above appliances plus microwaves, irons, heaters, coffee machines, and kettles as any products that need heat to function generally draw more power.
For more information on designing a battery system for your setup and how to calculate battery amp hours see our previous Powering Vanlife article on how to design the perfect power system.
What if I just buy the biggest inverter, won’t that keep me covered?
Put simply, it will. The larger the inverter the more appliances it will run but it will also take up more space and weight within your vehicle, which - if you’re travelling in a van - can be a valuable commodity. If you’re on a budget, a larger inverter will also cost more.
Having a larger inverter means more power drawn from the battery whilst running higher powered devices. This, in turn, means that you’ll need a bigger charger to put power back into the battery after it’s been heavily discharged by the inverter.
Larger inverters also have a larger standby current draw, meaning if it’s left on but not in use it will consume more power from your battery. This issue is easily fixed by turning off the inverter when not in use.
Swtiching off your inverter after use means it won't draw current while in standby mode
Pure vs Modified Sine Wave
Pure sine wave inverters are almost always recommended over modified sine wave as they are designed for powering sensitive electronics. With fully isolated input and output and protection against overloading or short circuiting, REDARC pure sine wave inverters produce less heat and less noise than modified sine wave inverters.
Cheaper, “modified sine” wave inverters can often lead to appliances overheating. This is due to the square wave having faster switching times on each polarity change, which stresses components designed for the much smoother transitions of a pure sine wave which almost identically replicates the output of the 240v 50Hz Australian AC power grid.