Generator Power

Power at any time - and lots of it! - you know in advance how much power you will have available, even if you don’t see the sun for a week. You can recharge your batteries in a few hours while you are at camp - rather than wonder if your solar panels will still be there when you get back to camp that night.

You can take along the luxuries you are used to at home - air-conditioning, electric-blankets, big fridges, microwaves etc.

When you’re not travelling, you can use the generator during blackouts, or to power appliances away from home.

Low cost and weight - currently a petrol generator will need less upfront expenditure and weigh less than any other method of generating several kVA of power.

Electrical power is measured in Watts - a bright light bulb uses 100 watts and the maximum that can be drawn from a home power point is 2400 watts - also known as 2.4 kilowatts or kW.
You may see output as kVA, and for many appliances this is the same kW, but for those appliances with motors in them, the kVA needed can be up to 50% more than the kW needed.

If the generator has a rating like 2400 watts and 1800 watts at 0.8 PF (Power Factor), this is just another way of showing the kW and kVA rating. When the PF is 1.0 then kVA equals the KW rating.

Two numbers are used to describe the output of a Generator - Peak and Continuous.

• Peak describes the output deliverable for several minutes - the generator’s components won’t blow up at that amount of load, but they will heat up quickly.


• Continuous ratings are usually limited by the heat that needs to be removed when running continuously.

Since the Peak is always more than Continuous, not surprisingly most Generators are described by their Peak output (Inverters are the opposite !).

So you may find that an 850 Watt generator can really only run a 600 watt load continuously. Ideally you would find out the Peak and the Instantaneous ratings of your appliances and check that they were less than the Generator output. But you can’t rely on this because most appliances don’t state the start-up or peak power needed and the length of the peak really needs to be known too.

Unfortunately the only way to be sure, is to test the appliance with the generator. Tables of power needs for appliances and compatibility with Generators (and Inverters) are available, but again, they’re only a guide.

Fuel Type

2 stroke - the lowest cost, but you have to put up with the disadvantages of 2 strokes - more noise, more fuel consumption, smelly exhaust fumes, plugs fouling etc.

4 stroke - most smaller generators are 4 stroke and all of the mid-priced generators are 4 stroke.

Diesel - these are only available from 2kVA and up, and have the advantage of less fuel usage than petrol and usually means you can have the same fuel for vehicle and for the generator. It also eliminates the explosion hazard of petrol.

LPG - only available for a few models of generator.

Low Oil cutout

A low oil warning is important, but only if there is someone nearby to hear it - it is far safer to have a cutout which stops the generator in case of low oil.

Overload Cutout

Not really optional, but the more sophisticated ones will protect against over-temperature as well as over-current, over-voltage or under-voltage (that can damage some appliances)

Fuel Gauge

It’s easier and safer than having to open the fuel cap!

Earth leakage protection

Bigger generators may have these built-in, but they can be easily added.

Meters

You can get by without voltage, current or frequency meters, but with them it’s easier to check if your system and appliances are healthy or if you are close to overloading your generator.

Battery Charging output

Whether you buy the cheapest two-stroke or the most expensive Japanese Inverter generator, the built-in charger is still totally unregulated and you could cook your batteries in a few hours. Consider this an emergency option only, unless you like living dangerously.

Eco/Smart throttle

Nearly all Inverter Generators have this built-in to reduce fuel use, noise and wear.

Paralleling two Inverter Generators

You can directly wire the DC from two batteries together, but you can’t do this with AC because the voltage changes from plus 335 volts to minus 335 fifty times a second. If you connect them at the wrong time there’ll be a big bang ! The outputs from two AC generators can only be connected together to power bigger appliances if the generators are synchronized so that positive peaks occur at the same time. This requires a special cable and connections, so if you need this capability, check before buying your Generators.

Noise

One of the benefits of going bush is the beautiful peace and quiet and the wonderful nature sounds, but even the quietest generator still produces some noise. You can minimise the impact of the noise on people by selecting the time of day you use it, where you put it etc, but in some National Parks they are banned and in other locations (i.e. near anyone with solar power) it’s just anti-social to spoil the bush silence.

Solar

The silence and zero running costs of solar are great, but you only have power for limited hours of the day and only on sunny days. But 1kVA of solar panels will cost around ten times as much as a 1kVA generator. You will also need bigger batteries than with a generator, to provide power when solar power isn’t available - and batteries are heavy and need to be replaced

Using 12 volt appliances

Many appliances are available as 12 or 240 volt versions (fridges, microwaves etc), but the 12 volt version always uses less power and is always more expensive! A 12 volt fridge will have thicker insulation and use a more efficient motor because mains power is cheap ! A 12 volt microwave will use less power because there are no losses in converting the 12 volts to 240 volts first. Using only 12 volt appliances may reduce your power needs so you won’t need a generator to provide more power.

Car Alternator

Modern vehicle Alternators can deliver up to 1.5kVA for a limited time, but it just isn’t practical to use your car engine for long periods of battery charging when stationary. You will use much more fuel and you will have problems with the engine bore glazing.

Bigger Batteries

If you only go away for a few days at a time, you can take more power with you rather than generating it while away - but batteries are heavy and need to be replaced.

Wind Generators

These are very practical on yachts and they keep getting cheaper, but are only useful for land travelers where there is regular wind and few trees.

Fuel Cells

In the next year we will see Fuel Cells powered by Methylated Spirit that will silently power a Notebook Computer for 8 hours at 50 watts - but don’t put off your travel plans waiting for a 500 watt Fuel Cell to cost anywhere near Generator prices!