Technical Stuff

Inverters


An inverter is the component of your RV power system the converts the power from your battery into 240 volt AC power so that you can run 240VAC appliances such as you run at home. Lithium batteries have allowed many RVers to live the travelling life style without foregoing the creaure comforts.

Do you need an inverter?

If you don't run any 240VAC appliances, the simple answer is no.

If you only run 240VAC appliances when you're connected to mains power, such as at a caravan park, again, no you don't need an inverter.  

But if you want the glamping lifestyle - air conditioning, coffee machine, electric blankets, air fryer, hair dryer and more - then yes, an inverter (or possibly even two) is the way to go.  

There is also a significant case to argue that you're better off with a domestic 240V household fridge than a 3 way, a 12 volt or (shudder...!) a compressor fridge.  Let's look at why:

  • A domestic fridge is significantly cheaper than the others.
  • We'll lay odds that in most cases it will do a better job of keeping your food cold.
  • If you buy a modern, inverter type fridge, we'll guarantee it will use less power.
  • You can find 240V fridge repairers much more easily than repairers of 12 volt, 3 way or compressor fridges.  
  • If the thing packs up and dies, you're replacing roughly $500 worth of appliance instead of about $2,000 worth.

I'm sure you get my drift.  The decision is yours.  At least now with lithium, you have a choice.

How big does an inverter need to be?

Well, this is basically a matter of adding up the number of watts each appliance uses that you are likely to run at the same time.  You need an inverter that will cover that number of watts, preferably with some to spare.

If you're happy to turn off your air conditioner so that you can use your microwave, then you can get by with an inverter that will run the largest power consumer.

IMPORTANT:  Things like air conditioners and fridges have a running current draw and a startup current draw.  The startup draw is larger, and it is this amount of power that your inverter needs to be able to cope with.  This is why you'll see inverters with two power readings - the lower is what the inverter can cope with for an extended time, the higher is what it can cope with for a very short amount of time to get an appliance up and running.  And yes, that "short amount of time" varies between inverters.

The importance of the standby current draw and why you may want two inverters

Larger inverters tend to use more power in standby mode than smaller inverters.  However, a larger inverter is often needed to power items such as air conditioners and microwaves, particularly if you want to run multiple large draw items at once.

A solution we have implemented often is to install a small and a large inverter.  The small one needs to have a low standby draw.  We recommend the Projecta IP2000, but funnily enough, the Projecta IP1000 has quite a high current draw.  Homework needs to be done when purchasing!

Multi-purpose inverters

Generally the domain of larger inverters, they often are a mains charger as well.  Some are even a solar regulator and battery monitor, but these are physically large inverters and generally more suited to off-grid home installations.




A happy wife is a happy life.
- Keith Moxham