Burned up regulator

cpotts454 · Posted: May 24, 2009, 9:55 pm Post subject: Burned up regulator

Quick question... what would cause a bike to burn up a rectifier? I built a new one off pamco's advice with the two rectifiers from radio shack and a heat sink from a computer cpu. 16 gauge wire. I've been using it for a season now and now its burnt up. I am getting 17+ volts on any series of whites coming from the generator.

Sooo, why would it burn out so soon? it never seemed to get to hot.

Thanks!

jayel · Posted: May 24, 2009, 10:51 pm Post subject: Re: Burned up regulator

what is the regulator output to the battery?

cpotts454 · Posted: May 25, 2009, 1:56 am Post subject: Re: Burned up regulator

Varied between 1.25 volts to 8 volts. I jumperd the regulator wire to the battery with no change.

pamcopete · Posted: May 25, 2009, 6:26 am Post subject: Re: Burned up regulator

cpotts454

Did both rectifiers fry? Was it mounted in a location where it got some cooling air?

If only one diode fried,you can move its white wire over to the spare terminal.

cpotts454 · Posted: May 26, 2009, 12:24 am Post subject: Re: Burned up regulator

I just now noticed I have the wrong title in this thread. Sorry guys.

Pamco, I installed it under the left side cover. I would assume it has enough air, but I would also assume below the battery box might be a better spot, I just couldnt figure out a good way of installing it there. It does however have one hell of a heat sink. Its a large heat sink from a computer. *Picture attached.*

How would I figure out which diode is bad?

Thanks guys!

pamcopete · Posted: May 26, 2009, 7:14 am Post subject: Re: Burned up regulator

With the rectifier disconnected from the bike, measure the resistance from each white wire to the red wire, then reverse the test leads and measure again. Should be a high resistance in one direction, low in the other.

Then, do the same thing with each white wire to the black wire.

If one of the white wires fails this test, move it to the spare terminal.

Also, did you put heat sink coumpound between the rectifiers and the heat sink?

There should be a threaded stud under the battery box where the stock rectifier was mounted. You can use that to mount the new rectifier so it will get some air flow to keep it from getting too hot.

Great looking heat sink!!

cpotts454 · Posted: May 26, 2009, 2:23 pm Post subject: Re: Burned up regulator

Thanks for the compliments. That isnt even a good photo of the sink, its got the heat fins threw out. Pretty cool really.

Yes, I did use heat sink grease before installation. Unfortunately the stock mounting stud is not long enough to bolt this bad boy on. But I am going to try and figure out a way to accomplish this. Thanks for you help Pamco.

xsleo · Posted: May 27, 2009, 2:53 am Post subject: Re: Burned up regulator

On my rectifier heat sink, I used a 1/4 inch thick piece of aluminum plate. It's what I had handy.
I mounted the rectifiers far enough apart to put a 5/16's bolt between them. A nut with a lock washer good and tight. Added a couple more nuts, till there was room for good air flow and the wires were away from anything. I ground the side of the bolt to fit the flat sided hole the stock rectifier mounted in. Just make sure the bolt don't stick up above the bottom of the battery box.
It looks like you have the room to put a bolt between your rectifiers. Either up thru or down thru will work as long as it's got good air flow.

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