regulator heat

Hey all,

How hot should a regulator get after a short trip around the block? I just installed a new one from oregon cycle and took it out for a spin. After, I could only hold my hand to the reg for a second or two, is this normal? Also, trying to check the voltage at the battery with the bike spinning 4k only gave me a voltmeter that was jumping all over the place, in fact it would start jumping like that even if I just held the vm near the bike without connecting the leads to the battery. Any ideas?

alexgehrig wrote:

Hey all,

How hot should a regulator get after a short trip around the block? I just installed a new one from oregon cycle and took it out for a spin. After, I could only hold my hand to the reg for a second or two, is this normal? Also, trying to check the voltage at the battery with the bike spinning 4k only gave me a voltmeter that was jumping all over the place, in fact it would start jumping like that even if I just held the vm near the bike without connecting the leads to the battery. Any ideas?

If it's a digital meter, you are not the first person to report that the EMI from the bike plug wires made it go insane. An analog meter will cure that if you can find one of them (I have three, but I'm really old).

As for a regulator module getting hot? It turns out that only able to touch for a few seconds is about 55 - 60C. Not comfortable to touch, but not amazing for an assembly that probably has the rectifiers in it. They conduct all the alternator current and that does dissipate some power. Solid state devices don't get unhappy until they get to about 125C.

The regulator on a KZ with the permanent magnet alternator (KZ that were equipped with solid state reg/recs from the factory) controller output current by dumping excess current as heat. If it's not getting hot then somethings wrong

Thanks for the input.

Yeah, it's a digital meter. I thought I'd be buying modern when I picked it up a few years back. Looks like I've got a good excuse now to buy an analog.

If the reg did get hotter (ie, too hot) could it be caused by a bad wire? I would think that bad wiring would cause a drain or a wire to heat up but not the reg.

That's the funny part about these solid state reg/recs, the greater the load on the electrical system the cooler they run. It's bleeding off current that is more than demanded that gets them hot, if the electrical system consumes all the power the alternator can put out, then the reg/rec don't have to dissipate and current as heat and runs cooler.

Would the careful application of the thermal(heatsink) compound help in the removal of excess heat from the regulator? The regulator must be removed from the mounting area, the faying surface (big word,means attachment point)cleaned, a thin coating of thermal compound applied, the regulator re-attached and properly tightened and this should aid in heat dispersal.

The thermal or heatsink compound can be purchased at any good electronic parts house or computer stores.

The thermal compound I am used to using resembles the white zinc cream people put on their noses for sunlight protection but it's not the same as it is silicone oil with a heat transfer medium.

Wouldn't you need two smooth surfaces to do this? The regulator and whatever you attach it too? It might be easier to move the regulator to a spot with more airflow.

I don't know if the heat sink compound would help or not, most of the heat is transfered through the fins on top.

MFolks wrote:

Would the careful application of the thermal(heatsink) compound help in the removal of excess heat from the regulator? The regulator must be removed from the mounting area, the faying surface (big word,means attachment point)cleaned, a thin coating of thermal compound applied, the regulator re-attached and properly tightened and this should aid in heat dispersal.

The thermal or heatsink compound can be purchased at any good electronic parts house or computer stores.

The thermal compound I am used to using resembles the white zinc cream people put on their noses for sunlight protection but it's not the same as it is silicone oil with a heat transfer medium.

Theoretically, it reduces the total thermal resistance but if the mounted device has a large surface area attaching it to the heatsink, the gain from adding the heatsink compound is small. I doubt if the change would be noticable.