Auto Alternator

I'm wondering if it is at all possible to get 120 / 240 volt AC single or three phase current from an auto alternator.

Mike

Yep, you can. I would be happy to answer any questions that you might have in this if you want. Try this site if you desire to see this being done by someone already;

http://www.qsl.net/ns8o/welcome.html

Spinning an alternator faster will give you more voltage, but one must consider that you are affecting the frequency as well. The faster it goes, the higher the frequency. Now when in use with the diodes in the alternator, it does not matter. Nor does some equipment that you may be powering care about it. But frequency dependent equipment, such as Florescent lighting, Televisions, and electronic equipment will have a cow with it. The best thing to do is up the amount of field current for it, but even that has limitations (as it was originally not wound for it). A simple formula for determining how fast to spin the alternator is to know the amount of poles in the alternator (I presume you desire 60hz AC);

speed = (Hz * 120) / poles

Hence a typical auto alternator of 6 poles (a Delco I have) would be required to spin at 1200 RPM for 60 hz. Now, at that frequency, if you place more current on the field, you could "adjust" the voltage to suite you. You might also want to consider reconnecting the typical "Delta" wired connections in the alternator to a "Star" configuration so that the current in the field would not have to be so high.

Anonymous

Frequency dependent equipment, such as Florescent lighting, Televisions, and electronic equipment will have a cow with it. Oops, I forgot something. Before someone says something about "I run my TV on 100 hz and it's ok", I need to add something. Yes, you can run some TV's at higher frequencies as well as some stereo's. It is dependent upon the equipment having a transformer, stepping down the voltage and using DC voltage for running the main circuitry off of this voltage. A good part of modern units sold today do this. However, my point remains.

Some electronic circuitry uses the input line frequency timing for operations, such as vertical refresh, clocks, etc. If the input frequency is not 60hz, timing will be affected. For some equipment the only effect it will have is the clock will always be off, or the screen will have trouble sync'ing. Some units will be affected, but display nothing that the user can see. Others will work like a champ, while still others will go ballistic. Best choice is to look for a unit with a transformer, and try it, but be watchful of its operation.

Bruce

Yes, you need to do three things, assuming the alternator windings are not modified:

1. Bypass the internal diodes.
2. Change the field regulation so that your desired output is the setpoint.
3. Spin it much faster.

The third requirement could be avoided if you are willing to rewire the stator.

Marty