My home made welder works

[phoenix]

Actually, that would only happen if you still had the internal regulator since it samples its output voltage to see what it needs to do to change the output. With no regulator, once the 12 volts is cut to the field, it is dead. there are no wires feeding the field besides your 12 volts from the ON switch. The field coil is nothing more than an electro magnet turning inside a three phase coil of wires. once the electro magnet is shut off, there is no more magnet to make power. The field requires about 10 amps to run, so I doubt there would be enough residual magnetism to really make any power. I guess it is possible though. I guess I could try to put a volt meter on the alt and turn the field power off and keep the engine running. that would be the way to test it out.

[randygar]

There's a slight amount of residual magnetism, but it's insignificant for most purposes. On some alternators the slight current it makes is used to tell the regulator to switch on.

--Randy

[randyscycle]

I gotcha'! Makes sense in a stock application, but a modified alternator wouldn't have that same setup.

Good to know.

[phoenix]

Just to finish this project, I thought I would provide my own schematic. Make sure that the power going to the fuse to run the control box is powered by switched power from ignition. It needs 10 amps. I had mine coming from the battery directly and already forgot and left it on once when I shut off the engine and was done welding.

[Mars]

Hello. I would like permission to post this thread to my advanced electrical class.( Cincinnati State Community and Technical College ) This is a great application to all the theory we're learning. Ohms law at work!

I would also love to see detailed plans and how you installed the second alternator so I can try and re-create it on my 715

Mike