Battery compartment heat insulation?

[sunny_nites]

Hi,

I've been experimenting with small lipo powered flashlights for a while. Because of the small size, there isn't a lot of metal to sink heat to and they tend to get pretty warm.

Trying to minimize the heat that gets to the battery compartment but all of the heat barrier material I've run across so far is way too thick. Then I ran across this on the internet:
http://insuladd.com/

It sounds promising and I was wondering if anyone has tried it or has any other suggestions for a very thin heat barrier material or paint.

Thanks!

 

[Wrend]

Styrofoam?

What kind of current are you draining from the cell(s)? How much power output/light output are the flashlights you're using?

I imagine the cells are getting pretty warm on their own accord too.

Of course the easy fix would be to use a lower power output setting... ;)

 

[45/70]

Hi sunny. I'd be wary of insulating cells, or I guess in your case packets. As Wrend pointed out, cells heat up as well as the driver/LED. Excessive heat kills any type of cell. It's best to assure that the cells/packets can dissipate heat through the light body. I suppose if your only running at low current rates, you could get away with insulating. Then again, at low current rates nothing is likely to get very hot anyway.

That said, I have no real experience with LiPo packets. It just doesn't sound like a good idea to me though. Cylindrical LiCo cells are relatively safe, compared to LiPo packets, so I just wouldn't try it.

Dave

 

[sunny_nites]

Thanks for the feedback.

It's mostly the form factor that I'm going for with the flat lipo cells. That and I just have more experience and am more comfortable with lipos as apposed to the round LiCo cells.

Relatively low power to the LED, 750mah on high. Think more along the lines of souped up keychain lights as opposed to say a 10amp Maglight. I'm using 330mah to 800mah lipos and modified x-micro drivers. The lipos and the drivers don't seem to generate very much heat even at high output. All the heat is coming from the LED itself.

I don't think there is any imminent danger from the heat to the battery compartment, just looking for any added safety or performance margin for battery life.

Styrofoam would be a good idea but it is too thick. Looking for something around.25mm thickness max. That is what got me thinking about the paint additive. It is relatively inexpensive so I will probably just give it a try. Was really just wondering if anyone had done research on heat barriers already and had any tips.

Thanks for the comments!

 

[VidPro]

I wouldnt believe that something like that would have any advantage over foamtape and mylar :-) That would be the first subminiature house type insulation block that i could think of making for a flatlight. the white type of foam tape which would have low thermal conductivity and an air gap, and simple foil or plastic foils (mylar) that could do a very minor "reflection" of heat.
similar and providing about the same results would be the simple thin packing foams , like the slick white sealed air type packing foams, air held in non motivational pockets (so they dont mix) would reduce the conductivity.

At any rate there is only ever so much that you can do, the biggest key would be to move the led heat itself out into the air, or to the persons hand as quickly as possible, and have any simple airgap (including just air) between the battery and the sink that is moving the heat off.

Fast move the heat to the outside, fins if you cant get enough surface area. I havent found anything that works perfect yet, always needs space or seperations (often way more than stuff provides that they sell even).

What is in existance that works , that would be put in a paint anyways, that would work better than air? a vaccume :-)
I am not sure about how effective reflectivity is, when there is not a very direct pointy radiation source to reflect, and a place for it to reflect OUT to so it departs? When the heat is all bound into a containment I dont understand where you would reflect it out to. Pretty much leaves having air gaps unless you can make vaccume gaps?

the paint stuff, is airgaps, miniature ceramic baloons, that would put tiny airgaps in your paint, for any well insulated home it would accomplish nothing, for this project it would do (about) the same thing as any airgap would. The paint? the paint itself would be negative increasing themal conectivity.