$$$$$$$$$ and a Google search.


Rod

I second Rod's $$$$.  The turn to turn insulation in a 12 to 24 volt alternator very likely cannot withstand 220-240 volts for very long before it breaks down electrically.  Additional insulation requires room - make the unit physically larger or remove windings, which limits thepower output.

Blacksmith

why would you want 1.8 amps @ 240 Volts?  

One way to do it is to remove the rectifier diodes and take the AC from the alternator windings into three transformers which step up the AC voltage to whatever you want. The output voltage regulation will not be good, and the frequency will be very high, and all over the place as engine RPM varies.

You can however rectify the output to create high voltage dc, and use this to control the alternator with some additional electronics. I did this years ago to generate +1200v 400mA dc, to power a mobile amateur radio transmitter before high power RF transistors were cheap and available as they now are. So it can be done.

I won't be so negative! First, do a google search for onboard welders and you will find an article that describes the NAPA box you can buy to get adjustable AC output from your alternator.  As they said, it is not clean power.  Best use is to rectify it and use the DC to drive incandesacent lights or universal ac motors (drills, grinders etc, the noisy kind with brushes)

I would be tempted to leave the alternator as it is, putting out 12v or 24v dc and simply attach an inverter. this will give you 230v ac + or - 10v and can be used to run a computer if you wish.

Inverters come as 300w about £40, 600w about £75. The wattage and price goes up. The largest I have seen is 2.5kw which is close to £300.   All the best.

Another option besides an inverter would be a motor generator.  I know Generac used to make one for 12VDC to 120VAC, with demand sensitivity.  This allowed for use of appliances like power tools without keeping the motor constantly running and draining the battery.

I may make you feel, but I can't make you think.

Why not just get a proper sized gas engine generator? I never could see much sense running a xxx horsepower car engine to produce the electricity that a xx horsepower engine could. Inverters are expensive and require LOTS of 12 volt amps to get 746 watts (1 HP) and the battery still has to be recharged.
I had this thought while I was using an air die grinder to do what a small Dremel tool could do, while being deafened by the noise the 1492 watt (2 HP) compressor was making to run a tool that might as well be 60 watts, and with a lot less noise.  :)

Pancholin.

Hello drp
Hello Drp,
Since you are in agricultural field, I can see the reasons of your exercise.
However, I strongly recommend you to explore different approach.

1)Use Kubota 3.5 KW diesel engine (horizontal) and Sawafuji generator.  This kind of combination will give you the lightest compact unit invaluable in the market place today.

2)You will be able to obtain 240VAC, 120VAC and 12,24 DC if required.

3)The Engine is water cooled (very quite)  furthermore, you saving on energy consumption.

4)Do not try to use gas engine/ generator in your application. As you have to run the engine once every month minimum otherwise you must empty the tank.  In Diesel engine case does not matter.

5)If you want to explore this option, your best pricing will be from companies selling generators for boats and marines applications. E.g. (www.nextgenerationpower.com)

Good luck