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240v Power Inverters

Everyone wants the benefit of having a mains power supply when in remote locations or on the road. The simplest way to achieve this is to carry a 240v generator set. However, generators can be heavy, fuel consuming, and noisy, plus you need to start them, whether remotely or by pulling a rope.

The easiest way is to have a 240 volt mains inverter connected to your vehicle batteries. The inverter can be permanently mounted, and power is available at the flick of a switch. Inverters are quiet, constant, and reliable providing there is sufficient battery storage to run them.

Inverters are available in several flavours, the 2 most significant being whether they produce a pure sinewave form, or if they are a modified sine-wave by trimming a square wave. Pure sine-wave inverters are best, as they truly represent our homebase mains power, but are the most expensive. Modified sinewave, or square-wave inverters are quite cheap, and produce a “dirty” waveform.

The cheaper inverters are fine for power tools and brush type motors, incandescent lamps, bar heaters and appliances with a constant load. Appliances like microwaves will snarl quite noisily as the magnetron detests the waveform produced, and sensitive electronics will also begin to deteriorate, particularly inductors and coils that begin to vibrate under the loads.

These problems are avoided by simply buying a “pure sine-wave” inverter for your sensitive appliances. Appliances today tend to have more and more sensitive electronics in them, compared to days gone by. Older microwaves simply had 2 knobs, timer and heat setting, whereas today they are a complete computerised electronic system. Just look at a modern dishwasher or washing machine with all their flashing LEDs, beeps and musical chimes as each cycle is activated.

Now off grid inverters are available in various input voltages. ie: 12v – 24v 48v. Most DIY motor-home builders tend to prefer the 12 volt systems for house battery power, as the majority of gadgets available today are rated as 12 volt. LED lighting, water pressure pumps, mobile phone chargers, television sets, etc etc, are predominantly 12 volt. Just remember, that 2400w inverter will be drawing over 200 amps at full power on 12 volts, whereas a 24 volt inverter at 200w would only be drawing 100 amps. (Current ratings based on Watts = Volts * Amps, no allowances for inverter losses)

By having a 24 volt system, you can use lighter wiring, and have less current draw, less heat, and less danger from protected shortcircuits. You simply use 24v DC to 12v DC mini-inverters to supply 12 volts where required. We run a 24 volt system for our motorhome house power now, as the Isuzu vehicle is also 24 volt, so we can simply recharge our house batteries direct from the engine when running. This avoids adding extra alternators to supply the house.

Selecting the Inverter Wattage

There is little value in having a 4800 watt inverter if you only use 800 watts on average. Remember, the 4800w inverter will be drawing 200 amps from the batteries at maximum power, so that’s really huge battery to inverter cables required to do that constantly. Also, your 200 amp hour battery bank is only going to do that for a few minutes before the batteries start to permanently deteriorate.

You need to evaluate what 240 volt appliances you are likely to be using, and for how long they will be running, and calculate the total watts used for that period. Forget running airconditioners from inverters, you don’t have enough battery storage. Things like the microwave generally only run for a few minutes, so required battery capacity will be less. Small microwaves tend to be around the 800 -1000 watt range, and may surge up to 1200 watts on magnetron start. Small appliances like kitchen whizzes are only around the 400 watt mark. Even large drills are around 750 watts. Televisions, Satellite equipment etc again around 50 to 200 watts. A washing machine or drier will be much higher, often several thousand watts. So decide exactly what you need the inverter for first.

We only use our inverter to run a small washing machine (300w), occasional power tools like grinder/drill (800w), vacuum cleaner (1200w), laptop power pack (100w), kitchen appliances (max 1000w), and very little else. So you see, we can get by comfortably with a 1200 watt inverter. It rarely gets used, as does our generator, as we rely so much on low voltage power in our motorhome.

We prefer to run 2 inverters. An elcheapo modified sine wave for large power tools etc, then a small 300 or 400 watt pure sine wave inverter for the laptop and sensitive equipment. This way, if one dies then we still have the other to provide 240v power in one way or another.

The modified sine wave inverters in 12 volt are selling for $50 to $100, whereas a pure sinewave inverter the same size will sell for at least twice the price. Our advice – save up and buy a good one – forget the cheap e-Bay Hong-Kong  inverters. We have tested a lot of them and most seem to only supply 190 volts at no load, and require a few watts of load to bring them up to around the 220 volt mark.  So if you are only pluggin in a charger or light bulb, then it is suffering at 190 volts and drawing much more current to operate. Also the cheapies are usually rated at 220 volts and not the Australian 240 volt standard.

Water Filtration

There is nothing worse than the “plasticky” taste of water drawn direct from most caravans and camper water-tanks.

Single Filter

This is so simple to overcome, and not by adding all these u-beaut chemicals to remove bad tastes either. A simple charcoal filter added inline will have your water tasting pleasant and a treat to drink.

However, if you are going to be using collected rain water or boiled creek water, then a 5 stage system is best as it will collect all the microscopic impurities found in water. Even fresh rainwater collected from your roof will have minute leaf and dust particles suspended within.

Naturally, flowing creek water will also have microbes swimming around, and a large proportion can be eliminated with a 5 stage system. Best of all is the reverse osmosis system, that enables you to purify and collect fresh water from virtually any water source. These are best used near running  streams, as they loose or return a majority of the water they are purifying. ie: You might recycle 20 litres to collect one litre in the filter’s storage tank.

Typical Water Filter

We recommend that you have a seperate potable water tap on your kitchen sink. These are usually in the format of the “Water Cooler” type taps with a curved delivery pipe on top. Connect this to a 2 or 3 stage filter, with a seperate charcoal filter on top and there you have it.

Water Sources and Supplies

Obviously we can fill our tanks from the town water supply at home, but on the road things can be different, and we need to keep on the lookout for good clean water, particularly potable or drinking water.

Rain:

Rain Water

Ahh the beautiful rain, the curse of many motorhomers and campers, but loved by me and all others who carry folding plasic buckets to collect the beautiful clear water flowing from our roofs and awnings. A long necked funnel is perfect for pouring all those 10 litres buckets of water back into your tanks. Some have even bothered to rig elaborate guttering and drainage systems to catch rain water, but I don’t mind doing it the hard way with the bucket brigade as I have more control over what goes in the tanks..

I have managed to refill all my tanks from just one heavy afternoon storm, enabling me another 7 days in the bush! I find that when the rain starts, by the time you get out all your buckets the annex is rinsed clean of dust, and I can line up the buckets under the edge of the annex, pouring them one a t a time back into the water tanks. When your tanks are full, let the buckets refill again, as that will take care of tomorrow’s water too!

Remember, rain water is the Potable stuff!

Crystal clear streams:

Crystal Clear Stream

The perfect opportunity to refill the tanks, providing you have a pump or buckets. Unless you are totally out of water, then do NOT contaminate your potable supplies with this stuff. Just fill the other non-potable tanks for the showers and washing etc. Speaking of washing, if you have found a nice clean flowing water source then maybe you need to wash some clothes while it is available.

It is not a great idea to use water from dams, lagoons, or other non-flowing sources. Always try for a river or stream that has a water flow, and try to collect you water from where it flows over rock formations as this will ensure it is aeorated.

 Rural Towns and Locations:

Rural Service Station

Be carefully filling tanks in country towns before enquiring first! That hose at the local Truckstop or service station may be connected directly to an underground bore, delivering very minerally and undrinkable water! While this may be fine for our showers, even though the soap may not lather, it is not the best for quenching your thirst.

Some bore waters often contain high mineral contents that will make you as thirsty as buggery. The more you drink, the thirstier you will get, and so on.

Water Hole

Some country town supplies are pumped direct from the local creek, and are intended to be used only on gardens of for livestock watering. Enquiring first will be the safest solution. I once watched a bloke who was very discreetly filling his tanks with a hose connected to a tap in the little council park adjacent to the public amenities block, in a tiny village in South-east Queensland. As I wandered around the host of beautiful flower beds there, I could not help noticing the powerbox above the bore casing at the lower end of the park. That’s right, there was a water bore below where the evaporation trenches for the septic toilets were located, and here he was pinching water from a tap that was clearly labled “Not for Human or Livestock Consumption”. Oh well, perhaps he benefited from his dose of heavy metals and mercurys, not to mention the other wriggling bugs in it.

Often small villages only have tankwater, that is replenished when it rarely rains, so shop-keepers are quite reluctant to let you top up your tanks. They usually seem to have those 5 or 10 litre plastic containers of water for sale inside though!

Water Storage Tanks

Water is the most essential ingredient of life. You can last for weeks without food, but only a matter of days without water!

Water supplies can be broken into 2 types:

1- Potable (Drinking – Pure)

2- Non-Potable (Showers – Washing up -Cleaning)

Potable Water:

We first need to consider the types of travel that we are most likely to undertake. This will help dictate the quantity of fresh or potable water that we need carry.

Boiling the Billy

Don’t worry too much about the minimums the survivalists quote, just consider that the average adult wants a few cuppas each day, and the kids will quaff a lot with their constant cordial drinks. I think nothing of having 6 – 10 cuppas a day, and a few cool drinks in the warmer months, so that equates to around 5 litres minimum per day for me alone.

So for an average family of 2 adults and 3 children, you would need 25 litres of potable water each day. If you intend spending a week at a bush camp, then you will need a fresh water tank of 200 litres (allows little remaining in the bottom of the tank).

Now this alls sounds great in theory, so lets chuck a few variables in. How many times did someone use the potable tap to rinse a cup? Who cheated and had extra drinks? Did you boil the spuds in potable water last night? Are you using the potable water to do the washing up with? How many times did Mum dampened a flannel to wipe the kids’ faces with? Did you fill the pets dish with potable water?

Water Cans

So here we are on day 6 of our camp and the pump suddenly runs dry. No problem, we will simply pack up and head 30ks back to town for a refill. Well here is another variable for you. The engine won’t start as the batteries are dead – then what, with no water? We wait another day for the solar to recharge them?

In reality, the 200 litre supply is only valid for 5 days of camping, and not 7 as calculated. Always carry a container of spare water. You can buy handy 5 or 10 litre plastic containers of water at the supermarkets, and always keep one stored away safely just for emergencies like the “flat battery” scenario above.

Non-Potable Water:

We like to classify non-potable water as from a flowing supply like a moving creek or stream. Non-potable is quite suitable for showering, washing, and even the dishes if it is boiled first. In a pinch, if you are stuck without water, then obviously we are going to boil the non-potable then cool it so we can drink it.

Stagnant Water

Lets face it, if you are dying of thirst in the outback and all you got is a puddle of stagnant water, then strain it, boil it, cool it, and hopefully you won’t get too sick from drinking it, but you will survive till help arrives.

Okay, so now we have determined that our non-potable water supply is going to be used for the shower, the toilet, windows, and even washing up. If you are bush camping with limited water available, then you should allow 4 litres of water per person for a shower. This is based on shower on wet down, shower off. Lather and shampoo up, then shower back on to rinse. Try it with one of those $20 solar camping showers, and you will find you can actually wash your hair as well with less than the 4 litres.

Washing dishes will require another 3-4 litres per session, and flushing toilets even more. So do your sums and calculate the daily minimum first, then allow a few litres more for the dog and the kids rinsing their feet etc.

Washing Up

My experiences show that the ratio of non-potable to potable consumed is 2:1. So for every 100 litres of potable, you should have 200 litres of non-potable. So you see, we really waste more than we drink. Yes I am sure that many can quote from their experiences where they can make do on 3 eye-droppers full a month in the Gibson desert, but we are talking about comfortable levels of living here.

Obviously, when you are near a good potable supply (ie: City tap water), then you would fill all tanks with the good stuff! Just remember, if you have had non-potable in a tank, then flush it 3 times well, before you fill with the potable stuff.

Contaminated Water

However, on the road things can be quite different. Many small country villages have creek or bore water on tap, and the good potable stuff is in their rainwater tanks. So when you reach for the hose at that little country garage, you might just be topping up with untreated creek or dam water, you know, the stuff with the dead sheep floating in it.

Most small service stations in areas of low rainfall are very reluctant to let you fill your tanks from their fresh water tank, and are more likely to let you fill a 5 litre container instead. If you are stuck then buy a few bottles of water instead.

The kitchen sink will also have non-potable water delivered from the hot-water system for the washing up, and rinsing of dishes. Actually, rinsing is one of my pet hates, I prefer to have an outside bucket of fresh creek water just for that purpose, it won’t kill you. Dirty cup, rinse and wash in the bucket, then a tiny rinse of water from the billy swirled around to kill the germs hey.