Mobius Thermal Tests

[BobDiaz]

I decided to post the results of my tests on a new thread so that those who want to look this up later on can find all the information in one place. The first comments on my tests appear here:

http://dashcamtalk.com/forum/threads/the-mobius-heat-issues.2392/page-7#post-39156

The comments by murcod pointed out that my readings may be off on the metal due to emissivity of the polished metal surface. I did take readings from the plastic and found those to be higher than the metal.

http://dashcamtalk.com/forum/threads/the-mobius-heat-issues.2392/page-7#post-39156

I did try to see if the reading was higher at the high data rate compared to the low data rate, but in looking for the highest reading for both tests, I could see no difference in the temperature readings. The room temperature was 68F (20C) and the highest reading found was 105F (40.6C).

Here are the thermal images I've taken so far:





There are a number of additional tests I'll be working on to see the impact of different conditions... Stay Tuned.


Bob Diaz

 

[murcod]

Hi Bob,

One other question on that camera - what is the maximum temperature it can read? The specs don't seem to give that info- only a temperature that appears to be the "operating temperature" (I assume that is the room temperature it can be safely operated at?)

Kestrel Mk II Camera Specifications
Diopter Adjustment +/-2%
Start up sequence <8 seconds
Thermal Sensitivity, Waveband <80 mK @ f/1.2
Display 320 x 240 LCD
Temperature Readout Displays Center Point Temperature +
Temperature Accuracy +/- 10% (based on .95 emissivity)
Still Image File Format and Size 320 x 212 resolution, 229 Kb
Operating Temperature 32°F – 140°F (0°C – 60°C)
Weight (including lens) 1.1 lb. (.50 kg)
Size 7" L x 2.5"H x 3.75" W

 

[BobDiaz]

Even the user manual doesn't say what the measurement range is . . . odd. The highest measurement I can find in the past photos I've taken was 269F (132C).



Yes that is a working model steam engine.

 

[murcod]

Come on Bob! Get some tape on that Mobius and please do a re-run.

 

[BobDiaz]

I did pick up a digital multimeter today with a temperature probe to add to the tests. However because of things I had to do today, I didn't get any additional tests done today.

Tomorrow I'm planning on re-running the first test again and use the temperature probe to double check the results.

murcod, I can shoot video of the tests, but it's not going to be a very exciting video. It's a bit like recording water coming to a boil.

 

[jokiin]

I can shoot video of the tests, but it's not going to be a very exciting video. It's a bit like recording water coming to a boil.

http://www.youtube.com/results?search_query=boiling+water 615,000 hits on YouTube says otherwise

 

[GJHS]

I can shoot video of the tests, but it's not going to be a very exciting video. It's a bit like recording water coming to a boil.

Add me to the list of people excited to see it. I think it will tell us a lot

 

[jokiin]

have been looking at the Innov C1 recently and ran one yesterday for half an hour or so and still cool to the touch, not even a hint of being warm, not so sure the heatsink on the Mobius is effective or even all that necessary, same hardware after all

 

[Gurkha9]

So are you saying that the metal case of the C1 removes heat faster?
My cam's heatsink can get quite warm to the touch after 30 min. so where would all that heat go then if the Mobius didn't have a heat sink? It's case is plastic of course.

 

[GJHS]

I asked Isoprop recently about venting the case. His advice for maximum heat relief was to remove the case all together, keeping the heat-sinks in place.

The heat issue is my only concern for future reliability and usability.

 

[jokiin]

So are you saying that the metal case of the C1 removes heat faster?
My cam's heatsink can get quite warm to the touch after 30 min. so where would all that heat go then if the Mobius didn't have a heat sink? It's case is plastic of course.

I'm not making too many assumptions, I haven't even seen a Mobius to compare, there has been some talk about the Mobius heatsink not having proper thermal contact with the processor, if that is the case it could quite well inhibit heat transfer and actually go some way toward holding the heat as the heatsink isn't exactly a heatsink in the normal sense, they generally have fins to increase surface area and help with heat dissipation, as I said I haven't seen one let alone pulled one apart to look at how well it has been done (or not), but I'm not sure how ideal the design is

 

[jokiin]

I asked Isoprop recently about venting the case. His advice for maximum heat relief was to remove the case all together, keeping the heat-sinks in place.

if you were going to remove the case I think a proper finned heatsink would do a lot more for cooling than the current one would

 

[GJHS]

Here are some pics from the RC forums
http://www.rcgroups.com/forums/showpost.php?p=25690121&postcount=1318
As you can see, there is a small heat conducting pad that presses against the DSP chip when the case is screwed shut. I think this would explain the glowing section around the heat sinks.

 

[jokiin]

Here are some pics from the RC forums
http://www.rcgroups.com/forums/showpost.php?p=25690121&postcount=1318
As you can see, there is a small heat conducting pad that presses against the DSP chip when the case is screwed shut. I think this would explain the glowing section around the heat sinks.

I'm not really sure what to make of that, to be fair sometimes these things are hard to make out in pictures, not sure how that would relate to the comment about removing the case but leaving the heatsink intact for example

Maybe @niko could shed some light on the construction

 

[iahim]

If Mobius would be able to produce and sell one half of the case in aluminium (the one with buttons), then all the heat issues would disappear for dashcam users. Of course, for RC users is irelevant, as they are always using it in open spaces.
New Mobius cams could be sold in both versions (with/without half aluminium case) or we (the ones that already have a Mobius) could buy this as an accessory.

 

[niko]

My proposal is to ad some vent holes / stripes into top and bottom part of mobius, which will create air free-flow, this way heat dissipation.
Even if heat-sink is properly attached to DSP and "collects" heat from DSP, then lets dont forget that CMOS also produces a lot of heat .... - where this heat goes ? .... it does not transfers too much to the DSP heat sink due to too small area of heatsink exposed inside mobius for surrounding heat to conduct., so heat from CMOS sensor trapped inside mobius body and causing overheating. There for need those extra went holes / stips so heat can escape.
Or the best solution would be as @iahim proposed: to make metal / aluminium casing / body. I would still add here some vent holes as well. I understand that aluminium body / casing would cost probably around 10usd more, but I am sure consumer is ready to pay this price difference.

 

[murcod]

murcod, I can shoot video of the tests, but it's not going to be a very exciting video. It's a bit like recording water coming to a boil.

Hi Bob, I'm not after video as such. Just the same test done with tape covering the heat sink- to change the emissivity of it into the range the thermal camera can accurately measure. So, a pic of that (like in the first post) would be fantastic.

You will see a big difference in the readings from the camera.

 

[GJHS]

My proposal is to ad some vent holes / stripes into top and bottom part of mobius, which will create air free-flow, this way heat dissipation.

I asked Isoprop that exact question
"Last question is: do you think venting the case will help at all with the heat?"

His answer was
"Venting will help a bit, but it also allows dust to enter which, in time, will not be beneficial. If you are really paranoid, then it would be best to remove the case altogether (keep the heatsink!), but then you'll need to fix your lens somehow. I think the heat issue is vastly exaggerated and only valid if you live in a hot climate."

I wonder how real of a problem this is. Do we need to take extra steps to fix it, should the Manufacturer redesign the case or is it an acceptable thing?

 

[niko]

I asked Isoprop that exact question
"Last question is: do you think venting the case will help at all with the heat?"

His answer was
"Venting will help a bit, but it also allows dust to enter which, in time, will not be beneficial. If you are really paranoid, then it would be best to remove the case altogether (keep the heatsink!), but then you'll need to fix your lens somehow. I think the heat issue is vastly exaggerated and only valid if you live in a hot climate."

I wonder how real of a problem this is. Do we need to take extra steps to fix it, should the Manufacturer redesign the case or is it an acceptable thing?

This proposal with drilling holes discussed many moth ago in main mobius thread but no design changes yet done. Maybe isoproo is right about dust if looking from RcGroups view. In car maybe less dust ( depending on car and coutry you drive ), but lets take as an exampke laptoo which collects a lot of dust inside, solution - comoressed air once in 3-6 month helps to keep it maintained. With small mobius yiu can just blow dust with your mouth when needed, no big deal.

 

[GJHS]

I agree Niko, May plan is a few small holes top and bottom to help heat go out and cooling go in. If I have to even go so far as opening the case and blowing out some dust every few months, it's worth it. As Isoprop said, it may be completely unnecessary, yet it makes the user feel a little better. I live in a warm climate, everyday is 70-80 F (20-27 C) so heat is everyday.