Heat sink for rectifier

XsJosh · Oct 7, 2020

So I changed out my rectifier for one from Amazon. It's rated for over 1000v and I think like 60 amps, I am going to make a mount for it and my vr115 regulator. Should I go with .125 or .25 aluminum? Also has anyone used syl-glyde as a heat sink grease?

gggGary · Oct 7, 2020

I'll suggest some sort of rubber/shock mount, preferably along with something heavy (battery?) so you don't make the shaking even worse.

XsJosh · Oct 7, 2020

It's going to be mounted to the battery box, hoping to use the rubbers from the old regulator. Found a friend with real thermal paste btw.

Max Midnight · Oct 8, 2020

Is it a combined rectifier/ regulator?
If so and it is a FET type r/r (which dump excess voltage to earth) they do get hot so good heat control is important. For that reason I would question if rubber mounting is a good idea as that would cut out one path for the heat to go.
If it is a MOSFET then they run much cooler so wouldn't need additional heat sinks.

As both types are solid state then I wouldn't consider rubber mounting necessary.

If it is to OE type then disregard all of the above. I'll shut the door behind me as I leave.

XsJosh · Oct 8, 2020

This is the rectifier I'm using, combined with a vr115 I'm seeing 14.5 just under 2000 rpms. (Still haven't actually ridden) my plan is to mount the 2 behind the left side cover where the stock regulator used to live on aluminum plate or plates. I'm thinking the rubber mounts of the battery box should be enough to protect them both.

650Skull · Oct 8, 2020

I used 2 single phase rectifiers in tandem. Mounts under the battery box as per factory..................gives me an extra diode if one craps out.

Not real pretty but who gonna see it........

5twins · Oct 8, 2020

I'm using the tried and true Windy Nation rectifier (about $10). It looks just like the single phase units Skull is using but since it's a 3 phase unit, you only need one. I also hang it from the bottom of the battery box, where the original one used to be. I mounted it on a section of heat sink I scrounged from an old computer .....

My VR115 is mounted to the side of the battery box where the original regulator was. It required a small adapter plate .....

Jim · Oct 8, 2020

To your original question.... 1/8" (.125) will work just fine. I think 1/4" would be severe overkill.
As was pointed out above, solid state devices don't object much to vibes so you can mount it anywhere. I mounted mine in it's original location behind the downtube (80SG)
As 5twins says, I like the windy nation rec. Small, cheap... and it works well for this application.

XsJosh · Oct 9, 2020

So this is what I've come up with so far, any thoughts? I used .125" stock mostly because its easier to work with.

XSLeo · Oct 10, 2020

Looks fine to me. The rectifier being a 60 amp with only 16 amps or a bit more then it probably won't need much of any heat sink.
As long as you side cover fits over it your golden.
Leo

TwoManyXS1Bs · Oct 10, 2020

Over simplified here.

The mass (weight, volume) of the heatsink determines its thermal capacity.

The heatsink's surface area determines its heat-shedding rate.

Comparing two heatsinks, same surface area, but one twice the mass (or volume, weight):

The lighter heatsink will heat up faster,
But both heatsinks will shed heat at the same rate.

Comparing two heatsinks, same mass (or volume, weight), but one twice the surface area:

Both heatsinks will heat up at the same rate,
But, the smaller surface-area heatsink will eventually run hotter, the other cooler...

TheMonkey · Oct 10, 2020

Oversimplifying thermal dynamics is Jedi work.

But @TwoManyXS1Bs is exactly right. Jedi?

Heat travels fast through minimal mass and travels slower through additional mass. Heat dissipates from surface area. Most heat sinks are designed to maximize surface area with a fast path to get there.

I’ve got the AMZN equivalent of the windy nation unit with a small AMZN heat sink... I’ve reached under the belly to cop a feel a few times under load and she’s just not that warm (stock headlight, stock alternator). I’d guess you’re fine and good to move on... looks nice BTW. Give it a feel under full load, if it’s hotter than you drink your coffee, needs more cooling.

Heat sink for rectifier

XsJosh

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gggGary

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Max Midnight

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XsJosh

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650Skull

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5twins

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Jim

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TwoManyXS1Bs

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