The Mobius & Heat Issues

[BobDiaz]

Adding a heat sink will never hurt, but it could help. Increased surface area results in more cooling.

bob price, If you live in or near the LA area, I have access to a thermal camera and could accurately measure the temperature and even take a photo of it when it's hot.

 

[bob price]

Adding a heat sink will never hurt, but it could help. Increased surface area results in more cooling.

bob price, If you live in or near the LA area, I have access to a thermal camera and could accurately measure the temperature and even take a photo of it when it's hot.

Thanks, but I'm in NorCal.
Somewhere in my basement there should be a digital surface gauge wife bought for some past reason.
I also have a collection of sinks left over from my computer building days. Might fab one to fit.

 

[bob price]

The heat sinks I added on were a preventative measure- there seem to be only a couple of documented heat failures (but a lot of talk about those couple of failures!) Heat is the major enemy of any electronic componentry, so the cooler you can keep any component, the longer it's life should be.

Where I live it can reach 45 C in summer- so if there are going to be heat related failures my odds of being a victim are pretty high. Summer will be here in a couple of months, time will tell. I've added the previous pictured heat sinks onto two of the three Mobius I own (the third is used as a rear facing camera and isn't exposed to direct sun.)

Good point. Prevention is always good.

 

[bob price]

Leaving Mobius mounted in car?
I read other threads in this forum and some say they remove from the car when not in use to prevent getting too hot in the sun.
Perhaps I am naive or just missing something, but the camera operating temps are so high that I don't see how even a sun-soaked car could ever get hot enough to damage.

Ambient temps could not come close to operating temps.

Or am I missing something? [I leave my camera in place so it's ready to go]

 

[germany]

Since I removed the heatsink there is no more overheating of the mobius. I just put this part out of the camera and obviously there is now enough air circulating.

 

[bob price]

Since I removed the heatsink there is no more overheating of the mobius. I just put this part out of the camera and obviously there is now enough air circulating.

Fascinating! And this is a dashcam? I could understand great air flow on a RC, but dashcam?

 

[jokiin]

Since I removed the heatsink there is no more overheating of the mobius. I just put this part out of the camera and obviously there is now enough air circulating.

if the thermal coupling was not good I could see how the heatsink could hinder rather than help the situation, the same processor is used in many cameras without heatsinks and no overheating issues

 

[Mtz]

Or maybe we can think were to make some smart and nice holes to help camera cooling and keeping the heatsink.
I have no experience regarding this but I have imagination and a drill.

enjoy,
Mtz

 

[murcod]

Since I removed the heatsink there is no more overheating of the mobius. I just put this part out of the camera and obviously there is now enough air circulating.

How did you determine that there is no overheating issue? The external parts of the case will now feel cooler (because the heat is no longer being transferred to the case), but I highly doubt that IC is running cooler internally.

Be careful or you might end up with a dead Mobius!

 

[murcod]

Leaving Mobius mounted in car?
I read other threads in this forum and some say they remove from the car when not in use to prevent getting too hot in the sun.
Perhaps I am naive or just missing something, but the camera operating temps are so high that I don't see how even a sun-soaked car could ever get hot enough to damage.

Ambient temps could not come close to operating temps.

Or am I missing something? [I leave my camera in place so it's ready to go]

The higher external cabin temps will raise the internal temps of the main processor IC - most likely by a corresponding amount. (Or put another way: the hotter the cabin temperature the less efficient the external heat sink will be at reducing the IC's internal operating temperature.) That reduction in cooling might be enough to push the processor IC past it's safe operating temperature range. The cooler you can keep active electronic components, generally the longer they will last.

 

[jokiin]

How did you determine that there is no overheating issue? The external parts of the case will now feel cooler (because the heat is no longer being transferred to the case), but I highly doubt that IC is running cooler internally.

Be careful or you might end up with a dead Mobius!

His comment was 'no more overheating' rather than 'no more running hot' make of that what you will

I'm not convinced that the heatsink design was that great really, allowing heat to dissipate freely may well work better, I've seen the same processor in some very cramped designs that don't have heat issues and have no heatsink

Further testing would be needed to see how well it works out but I'd keep an open mind at this stage at least

 

[murcod]

His comment was 'no more overheating' rather than 'no more running hot' make of that what you will

I'm not convinced that the heatsink design was that great really, allowing heat to dissipate freely may well work better, I've seen the same processor in some very cramped designs that don't have heat issues and have no heatsink

Further testing would be needed to see how well it works out but I'd keep an open mind at this stage at least

Sorry, it's the electronic's tech training in me drawing those conclusions.

If it was overheating before - with more heat sink surface area exposed to external air flow - then the heat is still in there somewhere.

 

[jokiin]

Sorry, it's the electronic's tech training in me drawing those conclusions.

If it was overheating before - with more heat sink surface area exposed to external air flow - then the heat is still in there somewhere.

I agree with what you say but I'm not sure the heat sink design and application is optimal to begin with

 

[germany]

Sorry, it's the electronic's tech training in me drawing those conclusions.

If it was overheating before - with more heat sink surface area exposed to external air flow - then the heat is still in there somewhere.

Ok as jokiin wrote I better should call it "running hot" than "overheating".

Without eletronics tech training it's a bit logic. When the box of the mobious is completely closed no air can come in for cooling it down. And this small heatsink I realy don't think this little crappy thing can do anything like cooling the sensor down. So it's better to leave the case open If you don't believe me you can remove the heatsink and test it for a few days then you will see what I mean.


PS: Sorry for my bad english

 

[murcod]

Your english is very good (better than some people I know who speak it as their only language!)

It could be better if there is a heat transfer problem between the IC surface and the heat sink, that actually wouldn't surprise me after pulling my Mobius apart. My "ideal" cooling set up would be a hole cut in the top of the case (directly above the IC) and a heat sink bonded directly to the top of the processor IC. There's a bit too much variance (in distance) between the outer case-> heat sink-> heat transfer pad-> IC surface/ PCB for my liking. Once they're all assembled it's hard to say if the contact is perfect between them all. It also relies on those tiny screws holding the PCB into the case to apply the pressure on those components to keep them firmly together.

It's very hard to say what's the best solution without being able to monitor the core temperature of the IC.

 

[bob price]

The higher external cabin temps will raise the internal temps of the main processor IC - most likely by a corresponding amount. (Or put another way: the hotter the cabin temperature the less efficient the external heat sink will be at reducing the IC's internal operating temperature.) That reduction in cooling might be enough to push the processor IC past it's safe operating temperature range. The cooler you can keep active electronic components, generally the longer they will last.

Sorry, I was not clear. I meant living the Mobius in the car after using it, when it's off, and you go inside. Others say they fear the camera getting too hot with the car just sitting in the sun. Since it's a dash cam, it most likely is attached on or near the windshield in direct sunlight.

I don't see how that could ever get hotter than when it's operating. My Modius remains in the car 24/7.

 

[murcod]

Sorry, I was not clear. I meant living the Mobius in the car after using it, when it's off, and you go inside. Others say they fear the camera getting too hot with the car just sitting in the sun. Since it's a dash cam, it most likely is attached on or near the windshield in direct sunlight.

I don't see how that could ever get hotter than when it's operating. My Modius remains in the car 24/7.

I agree, sitting there (off) shouldn't be a problem for the electronics, but I'm not sure what temps the battery can handle? The case might also heat up more than it is designed to handle - there is a post on here of a warped case.

 

[Isoprop]

If I remember correctly, the heatsink has undergone 3 design changes so far. The current heatsink, where the top edges are nicely rounded, certainly does a better job than the older versions. I agree with jokiin and murcod in that the design could be a bit better though.
The main problem, as I see it, is that the heatsink doesn't make direct contact with the DSP. To make direct contact, the part of the underside of the heatsink directly above the DSP would have to be raised higher than the rest of the aluminum. This would be to allow clearance for the numerous capacitors in the vicinity of the DSP. These capacitors stand quite a bit higher than the DSP itself. The thermal pad does exactly this, but thermal pads, despite their name, are not the best heat conductors. If the heatsink were to be in direct contact with the processor there will be another problem: Very precise engineering will be needed so that the heatsink is properly sandwiched between the top of the case and the top of the DSP. Any free space would make the heatsink wobble and thus lose contact with the DSP. Most probably a very thin thermal pad could be used, but I would prefer no pad at all, just an extremely thin layer of thermal paste to fill the cavities between the heatsink and DSP would be best.
Anyway, as it stands, the current design isn't bad at all. Heatsinks are designed to become hot, so there shouldn't be any worry. I am also not aware of more than a couple of mobius' being destroyed by heat, and perhaps there was another problem that led to the excessive heat. For example, a low quality power supply could easily lead to excessive heat, but that's another subject altogether . The developer has often considered using a metal case, but I much prefer the plastic molding which never becomes too hot to touch.

When we tested the prototypes we had to cover the surrounding components with insulating tape in order to attach the heatsink to the DSP and avoid short circuits. As I recall, the prototypes didn't have any thermal pads or paste so the heatsink was never in direct contact with the processor. However, the heatsink still got hot! The prototypes we tested came without the casing (the case wasn't ready at the time ) so there was plenty of airflow. However, I must warn against using the Mobius without a heatsink unless it is very well cooled. It will not last very long if you use it for continuous recording. A few minutes is fine though. Drilling holes in the casing will definitely help to keep things cooler.

 

[murcod]

Thanks for the input Isoprop.

 

[Mrnewbie]

https://www.ebay.com/itm/161114777425
An alternative way to keep it cool...but you might as well turn the sound off..