P60 Drop in question (regarding heat)

Hi all,

I have a question about the heat transfer issue with P60 drop-ins (Normal pill & reflector, not Malkoff kinds)...
What I read most of the time is to use ALUMINIUM foil to wrap the reflector to make it thick enough to touch the body so that the heat can be transferred to the body.

From what I read, Copper heat up more than twice as fast as the Aluminium and, will cool down quicker at the same rate. But Aluminium has better heat transfer. (Correct me if I am wrong)

So, I happen to have copper & aluminum adhesive tapes, so I thought of trying the following:
Base layer of tape: Copper (To conduct the heat faster)
Last layer (touching body): Aluminium (To transfer heat to body faster)

What do you all think?
Or does anyone has a tried & tested way of improving the P60 drop-ins heat issues?
Thank you!

Copper > Aluminium

enomosiki said:

Copper > Aluminium

Click to expand...

So I should just stick to copper all the way?
Hmm, that will make things alot simpler.

Copper and aluminium touching will corrode like crazy too.

Copper is better than aluminum. Hence why most heavy modders use a copper slug to transfer heat away from the emitter ASAP.

Copper conducts heat better than aluminium. Copper tape will allow the waste heat to be transferred to the body of the flashlight faster than aluminium. Copper is, unfortunately, more expensive compared to aluminium, but if you are serious about using a P60 setup, copper is the way to go.

So, yes, stick with copper if money is no issue.

Sp@rky said:

Copper and aluminium touching will corrode like crazy too.

Click to expand...

Wow, thanks for the info.
I was thinking of running some test with a mixture of alu & copper tapes but I dont think i am gonna try that now.

You usually only need 2-3 layers of tape, so cost should not be of any concern
(as not is the higher weight of copper - in this application)

yellow said:

You usually only need 2-3 layers of tape, so cost should not be of any concern
(as not is the higher weight of copper - in this application)

Click to expand...

But 2-3 layers cannot get a tight fit of the P60 into the flashlight.
I usually have to go 5-6 layers.

I read that the purpose of the copper/aluminium layers is to make sure that the P60 has full contact with the flashlight body, so that the heat-transfer can be effective. That is why I layer so many times to make them tight fit...

Correct me if I am wrong
Thank you!

DellSuperman said:

But 2-3 layers cannot get a tight fit of the P60 into the flashlight.
I usually have to go 5-6 layers.

I read that the purpose of the copper/aluminium layers is to make sure that the P60 has full contact with the flashlight body, so that the heat-transfer can be effective. That is why I layer so many times to make them tight fit...

Correct me if I am wrong
Thank you!

Click to expand...

Yeah, you want the drop-in to fit as snug as possible.

The amount of tape you need depends on the host. Some have wider inner diameter, and others narrower.

Alright, thank you for your verification..!
Cheers mate.

DellSuperman said:

Hi all,

I have a question about the heat transfer issue with P60 drop-ins (Normal pill & reflector, not Malkoff kinds)...
What I read most of the time is to use ALUMINIUM foil to wrap the reflector to make it thick enough to touch the body so that the heat can be transferred to the body.

From what I read, Copper heat up more than twice as fast as the Aluminium and, will cool down quicker at the same rate. But Aluminium has better heat transfer. (Correct me if I am wrong)

Click to expand...

I'm agreeing with enomosiki on the snug fit and pretty much with everyone else in this thread.

Just like a heat sink attached to a computer part, solid contact is required. A loose heat sink can be worse than not having one at all. Just a foil shim to make the heat connection, so to speak. Thermal compound can also be used.

Copper has a higher specific heat than aluminum. That is to say that by mass, copper can hold more heat than aluminum. This isn't necessarily a good thing for a heat sink, but it's a better heat conductor than aluminum. The second reason is why it's used in the better heat sinks rather than aluminum.

It's the cheap heat sinks that are made of aluminum.

To increase the rate of heat transfer to air, the external surfaces touching external air should be roughened or perhaps bead-blasted before finishing to increase surface area. An externally polished heat sink will radiate less heat due to less surface area than one that's rough-cast or roughened up by some method. More surface area to the air means faster heat transfer.

To reduce the differential metal corrosion (that is aluminum touching copper in an electromagnetic field,) try thermal compound at the joint. Auto-parts-store "Dielectric grease" also works.

I tried copper adhesive tape on my solarforce lights, the adhesive severely limits the thermal path. Im thinking of changing to aluminium foil without adhesive. Maybe try and experiment if you have a way of measuring the temp.

PapaLumen said:

I tried copper adhesive tape on my solarforce lights, the adhesive severely limits the thermal path. Im thinking of changing to aluminium foil without adhesive. Maybe try and experiment if you have a way of measuring the temp.

Click to expand...

I am not sure how effective (or ineffective) mine is.
But after running the light for a long period of time, the bezel gets quite hot.
So I am assuming that the heat is being transferred from the drop in to the bezel pretty effectively.
What I did was after applying 1 layer, I will roll the reflector on the side of my table to flatten it & repeat for every single layer to make sure that the gap between the tapes are kept to a minimum.

And nope, I don't have anything that can check the temperature. :shakehead

Another thing that helps is to smooth the foil out first to get rid of the wrinkles. Wrinkles make it hard to squish out the air gaps. I have been able to stuff twice as many wraps around my dropins when flattening using a smooth surface and a flexible "squeegie" (I use a credit card type of card, flexible and flat edged), as opposed to simply flattening it by squashing it with my palm. I have also noticed that the outside of the head heats up more noticeably than before.

Also, for those using the adhesive backed copper foil, a dip in isopropyl or other solvent and some careful wiping may help get rid of that insulating layer of adhesive.

Have you read Improving heat sinking on P60 style drop ins..

Norm