Proper Heat Sink for SSC P7

atvman29 · Jul 21, 2009

I've been browsing these forums a lot lately and have found a lot of useful information. some of the things you guys have done is just awesome!

Anyways, I'm looking to build a light to run on an ATV or other offroad vehicle using SSC's P7 C-Bin LED. They're offered at DX for a little over $15 a piece. To run it, we're going to use three of these from DX as well. Accoring to the research I have done, this should allow us to run it off the 12V system of the ATVs, and also coincidently allow for a high medium and low setting (if we choose to put switches on them).

Am I correct thus far?

But I'm a little confused on the heat sink for it. I was looking at the product brochure for the P7s that SSC has on their site, and I saw that the thermal resistance is 3 C/W. So doing a little searching, I found these and the 72mm heat sink also has a rating of 3 C/W.

So is that the one we need? Judging by some of the other heat sinks I've seen people using, it doesn't seem far off. But again, I would like to go as small as possible.

Any help or guidance would be greatly appreciated, thanks.

supasizefries · Jul 21, 2009

Those drivers you linked will be underdriving the p7 by a large margin. Maybe that's your intent but if you want approx. full output you'll want to drive them at 2.8 A.

atvman29 · Jul 21, 2009

supasizefries said:
Those drivers you linked will be underdriving the p7 by a large margin. Maybe that's your intent but if you want approx. full output you'll want to drive them at 2.8 A.

Shouldn't three of them in parallel put out 3 amps? Sorry if I didn't make that clear, but we were planning on running three in parallel per LED.

That should work, correct?

AlexGT · Jul 21, 2009

I think that using 3 driver boards with modes in parallel will not work because they might go out of sink and end up being a mess (1 in high, 1 in medium, 1 strobe for example)

Why not one of this with modes and rated for up to 15V?

http://www.kaidomain.com/ProductDetails.aspx?ProductId=5595

HTH
AlexGT

atvman29 · Jul 21, 2009

AlexGT said:
I think that using 3 driver boards with modes in parallel will not work because they might go out of sink and end up being a mess (1 in high, 1 in medium, 1 strobe for example)

Why not one of this with modes and rated for up to 15V?

http://www.kaidomain.com/ProductDetails.aspx?ProductId=5595

HTH
AlexGT

I don't believe they have modes, I had just read you could possibly switch the individual drivers so you could choose between running 1, 2, or 3. This would change the brightness of the LEDs by reducing the power input.

I'm not too interested in running it on lower settings, but it'd be cool to have the option.

atvman29 · Jul 22, 2009

Any opinions or suggestions on the heat sinks we found?

atvman29 · Jul 24, 2009

Anyone? We'd like to order them soon.

supasizefries · Jul 24, 2009

I don't have any experience with that heat sink so I can't comment on it. One thing to check is to see if it's anodized or not. It doesn't look like it is but you can ask the vendor. If it's not, then you'll have to electrically isolate the metal slug on the back of the p7 before you attach it to that heat sink.

atvman29 · Jul 24, 2009

supasizefries said:
I don't have any experience with that heat sink so I can't comment on it. One thing to check is to see if it's anodized or not. It doesn't look like it is but you can ask the vendor. If it's not, then you'll have to electrically isolate the metal slug on the back of the p7 before you attach it to that heat sink.

Does it make sense to you that as the extrusion length increases, the thermal resistance goes down? It seems to me that it should be the other way around.

jar3ds · Jul 24, 2009

AlexGT said:
I think that using 3 driver boards with modes in parallel will not work because they might go out of sink and end up being a mess (1 in high, 1 in medium, 1 strobe for example)

...
AlexGT

seriously? Does this happen? I was planning on doing this myself with a maxflex.... has there been any threads on this topic?

I wondered if this was possible but then i thought that its a complete circuit so i wouldn't think that they could really get out of sink...? :sssh:

Aircraft800 · Jul 29, 2009

jar3ds said:
seriously? Does this happen? I was planning on doing this myself with a maxflex.... has there been any threads on this topic?

I wondered if this was possible but then i thought that its a complete circuit so i wouldn't think that they could really get out of sink...? :sssh:

You can't parallel MaxFlex drivers, I asked George from TaskLED somewhere here in the forum.

atvman29 · Jul 29, 2009

Aircraft800 said:
You can't parallel MaxFlex drivers, I asked George from TaskLED somewhere here in the forum.

So what I'm trying to do won't work?

If not, how would I run a P7 off a 12V system?

jar3ds · Jul 29, 2009

i just confirmed with george too... no parallel on maxflex... really sad though because this would open a lot of doors... seems that shark is our only parallel boost option...

atvman29 · Jul 29, 2009

Are the drivers I have listed in the 1st post maxflex? I don't see that anywhere on the page.

supasizefries · Jul 29, 2009

MaxFlex

I'm unfamiliar with the relationship between extrusion length and thermal resistance.

atvman29 · Jul 29, 2009

supasizefries said:
MaxFlex

I'm unfamiliar with the relationship between extrusion length and thermal resistance.

They look a little different to me.

Are they the same ones? i hope this works because DX ships S-L-O-W :p

supasizefries · Jul 29, 2009

They're totally different drivers. I think someone in this thread previously inquired about doing the same thing you want to do with DX drivers except with maxflex drivers. If the drivers you are using have no modes, it might be possible? :confused:

Also just a tip, it's frowned upon to hotlink pictures from other sites here on CPF. You might want to copy and save the pics to your own hosting site and then post them.

atvman29 · Jul 30, 2009

supasizefries said:
They're totally different drivers. I think someone in this thread previously inquired about doing the same thing you want to do with DX drivers except with maxflex drivers. If the drivers you are using have no modes, it might be possible? :confused:

Also just a tip, it's frowned upon to hotlink pictures from other sites here on CPF. You might want to copy and save the pics to your own hosting site and then post them.

Alright, well I guess we'll see. We just ordered one of each of the heat sinks.

Thanks for the tip on the photos.

ecotack · Aug 4, 2009

jar3ds said:
i just confirmed with george too... no parallel on maxflex... really sad though because this would open a lot of doors... seems that shark is our only parallel boost option...

With a maxflex you'd be better off with a Cree MC-E and the dies in series (will need 1 per MC-E though). Presumably the P7s are in parallel (never used one, but have used an MC-E).

If the drivers the OP was looking at can be used in parallel (I've some on order from DX so don't know for sure yet, but SKU 13557 will, neither have modes), then wiring 2 P7s in series and 3 drivers in parallel would work. The drivers probably won't be able to supply the voltage for 3 P7 in series. Switching the drivers independently will give 3 brightness settings.

I've used one of the drivers AlexGT pointed out at KD, but you will need one per P7, I don't think they can power 2 in series, won't do 3.

old4570 · Aug 4, 2009

12 Volts - KD has a driver 3 modes , that should be fine ..
Depending on how you design the light , will dictate the design of the heatsink .

You could try a CPU heatsink ? Again depending on your design .

Driver from KD

Proper Heat Sink for SSC P7

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