If you camp out of a car, caravan, RV or camper trailer, running 240V appliances is a common problem faced. Unless you are at a powered site in a Caravan park, you need a different solution, and there are actually a number of different options.
In this post, we look at the different options you have, and what you need to know about them.
The first option is to run a 12-240V inverter. This is not new technology, and involves the use of an inverter, which takes 12V DC power from your vehicles battery (or caravan/camper trailer/RV, boat) and converts it into 240V AC, like what you’d use in your home.
Now, there are some severe limitations depending on what sort of setup you have, so please don’t think you can take your fan heater with you, or a portable air conditioner without some serious gear (and of course expense!).
The other alternative is to run a generator, which a lot of people still use but with the way technology is going are fast becoming the less popular option.
12V to 240V inverters
If you want to know how to run 240V from a 12V battery, its done by using a device called an Inverter. These can be purchased from about $80, and work their way up to the thousands, depending on what size they are, and what sort of quality they offer.
Basic inverters start off at around 100 watt, and for the purpose of camping, go up to about 6000 watts mark. However, just because you have a big inverter doesn’t mean you can run appliances that use a lot of power; there’s a bit more to it than that.
Pure sine wave inverters
The cheaper inverters on the market provide electricity that is not a very clean waveform, and ultimately is poor quality power. This is fine for charging batteries, or running lights and other gear that you aren’t too concerned about.
However, plug in sensitive electronics, and you can do some pretty nasty damage to them. This includes laptops and other expensive electronics.
If you want to run quality, sensitive gear off an inverter, make sure its pure sine wave. You pay a bit more, but will save a fortune when it doesn’t destroy your nice electronics.
How does an inverter work?
Inverters take power from your battery, and convert it into 240V. The smaller inverters take power directly from a cigarette lighter, or using alligator clips on the battery. Bigger inverters tend to plug in via Anderson plugs, or if they draw over 50 amps are permanently attached to a battery using lugs.
There is some loss in the conversion between DC and AC; usually around the 10 – 20% mark. This means if power consumption is an issue (which it usually is when camping) sometimes you are better off buying a 12V appliance. For example, you can buy the Ryobi 18V battery chargers in both 240V and 12V.
Inverter or 12V chargers
For a long time, I used a cheap 150W inverter from Dick Smiths to charge the basic items; an old laptop, camera batteries and occasionally other random bits and pieces.
I wasn’t worried about the laptop dying from the inverter not being pure sine wave, and it never did any damage. I actually purchased a number of 12V chargers for the different gear, because its easier to use and less hassle.
However, not too long ago I purchased a decent laptop to work with while travelling, and I looked at the cost of a 12V charger, which was about $50, and what I’d have to buy in the future, and decided to pick up a 350W Projecta Pure Sine Wave inverter instead, for about $200.
350W will run most of the appliances that people want to run, unless you want to move into items that cook or heat.
That said, you can usually buy 12V chargers for most appliances, that will run off an Anderson or cigarette lighter plug and this can be a good option if you don’t want to deal with an inverter.
Jaycar sell universal 12V laptop chargers for example, which completely do away with the need to deal with 240V power at all.
What appliances can you run from an inverter?
This part is actually pretty simple; check your inverters maximum rating, and the maximum current draw (which is often very high on start-up) of the appliance you want to run. A 900W grinder can sometimes pull 1400 – 1500 watts on start-up, so factor that in.
Providing you are under the rating, your inverter will run the appliance. However, the harder you work them, the more likely they are to break (pushing an inverter to, or beyond its maximum limits will reduce its lifespan).
Also, just because your inverter might be able to power it does not necessarily mean your battery system will; see below.
What size inverter should you fit?
The bigger the inverter, the more you’ll pay for it. Sure, you can get some cheap 2500W inverters, but they won’t be pure sine wave and realistically, running 2500W off a normal battery system is asking for trouble.
Why? I hear you ask. Most car alternators can charge at a maximum of 70 – 130 amp hours. This means every hour the vehicle is running at a reasonable RPM (not idling) your battery has the potential to charge at the rate above. For most vehicles, its on the lower end of the scale, but for this exercise, lets call it 100 amps an hour.
100 amps an hour is anywhere between 1200 and 1400 watts on a 12V system. If you run anything above that, your alternator will not be able to keep up, and if you are planning on doing it off solar you are going to need a significant sized battery system and solar array.
Our Bull Motor Canopy came with a 2500W inverter, which the previous owner used to power a microwave, to heat his lunches up on site. Now that’s not such a bad idea, as the inverter would be supplying around 1800 – 2200W, but only for a few minutes. As long as you do it with the car on and accept that your battery life probably will be decreased a bit, there’s no real drama.
Pulling a lot of power for any length of time out of a battery isn’t very friendly for it, unless its got the correct discharge rates (which you should be able to find in the battery documentation).
There are some pretty amazing caravan battery setups these days with huge amounts of solar, lithium batteries and these will run massive inverters very comfortably for a long time. However, to get that sort of system installed you are looking at a substantial investment; around the 3 – 20 grand mark!
We’ve actually just upgraded our Reconn R2 with a lithium battery and solar upgrade, costing around 3k plus installation, which will run any appliances up to 3000W. We’ve been running an induction cooktop for a little while now, and the odd other appliance (it will happily run the an aircon or household kettle!), and our limitation is more how quickly we can re-charge the batteries, than what we can run.
Inverters are great when used sensibly
Inverters are fantastic, when used in a logical manner. The power coming out the other side is 240V, and when used incorrectly can kill you. If you are hooking them up to power outlets, you need the relevant RCD’s, and installation needs to be done by a licensed electrician who signs off on the work.
Use inverters to run gear that suits your setup; push it too far and something is going to have its life shortened. For us, I can’t see the point of running anything over 350W, so a small inverter does us just fine. Will that change in the future with lithium batteries and other appliances? Maybe!
How much power is actually used?
I see comments all the time from people who have a 12V system, and want to use high energy consuming appliances. It is possible, but you need to understand exactly how much power is being drawn, as doing it off a battery system is vastly different to flicking the switch on at home when you are connected to mains.
Remember that you need to consider not only the instantaneous power draw, but how long you use it for. Whilst a coffee machine can draw a lot of power, its only for a couple of minutes and the overall consumption might not be too much.
That said, below is a few examples of how much power you’d expect to use on a 12V system, along with how quickly it would flatten a single 100 amp hour battery (using the full amount, which you should not be doing!).
TV’s and screens
Most caravan TV’s and screens will use around 3aH, and would take 33 hours to flatten a 100aH battery
Double toasters (not the 4 slice ones) use around 850W, which means you’ll be pulling around 75aH to run one. You’d flatten a 100aH battery in an hour and 20 minutes.
Kettles draw around 1500W, which is about 130aH. You’d flatten a 100 amp hour battery in 45 minutes.
Caravan Aircons use around 2000 – 3000W, which is 160 – 240aH. You’d flatten a 100 amp hour battery in 25 – 40 minutes on high. It is worth noting that these can use a lot less on low power settings, but they are power hungry.
Air Fryers, Induction Cook Tops and Microwaves
All of these 3 items use between 800 and 2200W, and will flatten a 100aH battery in 34 – 94 minutes.
Caravan washing machines are actually quite energy efficient in terms of electricity, and generally pull under 300W (unless you are using the heating elements). You’d get about 4 hours out a 100aH battery
Coffee pod machines
Coffee pod machines can draw up to about 90 amps, and would flatten a battery in just under an hour (but you don’t use them for that long!)
Your system needs to be able to recharge itself
If you use 100 amp hours in a day, you need to be able to put that back in. A 100W solar panel is going to put about 30 – 35 amp hours back in each day, and so you can see that a big solar array is needed if you want to run high consumption appliances off grid.
Using a Generator
With the way that technology has gone, generators are often not looked at overly favourably, and if you run one amongst a group of people in anything but a generator designated site, you might get a few sour looks.
In essence, you can have a battery and solar setup that will rival a generator, and it is free to run, doesn’t make any noise, or smell at all. That said, generators have their place, and a lot of people still use them. They will run larger appliances easier than trying to do it with a battery system, including air conditioners, microwaves, air fryers and so forth.
They are also a great solution when its overcast and your solar struggles for a number of days on end. If you haven’t got a generator in this situation, all you can do is run your vehicle which is far less economical.
Camping at a powered site
The alternative to these two options is to pull into a powered site, at a Caravan Park, or private residence. Some people love the feeling of staying at a Caravan Park, and others much prefer the bush, away from the hustle and bustle. Each to their own, but it certainly does affect how you can run 240V appliances!