what's wrong with this plan?

[Al Derocher]

Hello, i'm a newbie. I am attempting to build a vawt system to create heat. i have a design for a vawt turbine, i have a car alternator that has been rewired so it puts out 3 phase power, it came with a rectifier to convert the power to 12 volt DC. I have a 300 watt, 12 volt heating element, and a deep cell 12 volt battery. The advertising says that the alternator will put out 12 volt DC at approx. 150 rpm. Sooo, if my vawt turns fast enough, and has enough power to turn the alternator, will this system work? What happens if I turn it faster, say 300 rpm? I am eager to build, but know very little about the electrical part of it. ANY comments will be greatly appreciated! AL

[Rob Beckers]

Al, welcome to the forum!

I would encourage you to build it and do some testing. Nothing is as educational as actually building something.

If you are looking for a more general background: Directly heating from a wind turbine usually doesn't work too well. The power output of a wind turbine increases with the cube of the wind speed (so Power = speed x speed x speed x factor), while the power dissipated by a resister/heater increases with the square of the Voltage (so Power = Voltage x Voltage x factor). The Voltage out of a wind turbine is somewhat linear with wind speed, so double the wind speed, double the RPM, and double the Voltage (roughly, it veers away due to losses). That means you can match the heater output for a specific wind speed, but it will be off for every other wind speed.

The other part is that it's hard for a wind turbine to get started with a load (heater) connected. You need high starting torque for that, and most turbines don't have high starting torque, they start from a condition where the blades are stalled.

That's the theory. Building one and testing is infinitely better and more fun! And you can prove me wrong! :blink1:

-RoB-