Mobius Super Capacitor.

[jokiin]

I don't believe the processor has anything to do with those that have had heat related issues

 

[niko]

Has the processor got thermal protection built into it? (ie. it shuts itself down when overheated?) If it hasn't then I wouldn't like it's chances of working again simply from cooling down.

As I remember correctly it should be +47C when processor thermal protection power-off Mobius, but I am not sure if its built into CPU or works via FW ?

 

[jokiin]

As I remember correctly it should be +47C when processor thermal protection power-off Mobius, but I am not sure if its built into CPU or works via FW ?

I've read that number before also but it must be something they've implemented, I know Innovv has done a 70c test on their camera so the processor is certainly not going to have issues at 47c

 

[niko]

I've read that number before also but it must be something they've implemented, I know Innovv has done a 70c test on their camera so the processor is certainly not going to have issues at 47c

This figure of +47C set by Mobius FW.
NT96650BG-ES
- Storage temp: -55C +125C,
- Operating: -10C +70C

 

[murcod]

Thanks for that link Niko, from it (directly below the table snippet you posted):

Comment
Stresses above those listed under "Absolute Maximum Ratings" may cause permanent damage to this device. These are stress ratings only. Functional operation of this device at these or any other conditions above those indicated in the operational sections of this specification is not implied or intended. Exposure to the absolute maximum rating conditions for extended periods may affect device reliability.

I couldn't find anything mentioning any temperature related safety features when I scanned the data sheet.

So, does the Mobius have external temperature monitoring/ shut down to the DSC/DV Processor?

The figure of 47 degrees was mentioned in another thread recently http://dashcamtalk.com/forum/threads/mobius-thermal-tests.3423/page-3

Mobius is rated to 47deg C, & the vehicle interior temperature will exceed that when parked with aircon off.

I hope it survives indefinitely, but...

Is that perhaps from the operating instructions document?

 

[murcod]

From another thread - no mention of any safety devices built in

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.

The bit in bold suggests to me there is no safety shutdown.

Edit, some more - with 47 degrees mentioned again :

If anywhere, this should be integrated in the DSP. However, I have never had any problems with heat issues and we tested the pre-release cameras without proper heatsinking and measured high temperatures. From the start we have known that heat can be an issue with any 1080p DSP. I even posted my feelings about this on the #26 RC thread long before the #26 was released because I knew that the Sunplus DSP (used in the #26) produces more heat than the Novatek. One user even told me that the #26 had no heat issues, even though it hadn't been released
I think too many people are afraid because the heatsink on the Mobius becomes very warm (hot), but that's the purpose of a heatsink! I know there have been one or two reports of the camera suffering from heat damage, but this is a tiny percentage of all all the cameras sold.
The developer also found that a weak external power supply can drastically increase the internal heat because the charger IC will constantly be charging/not charging the battery. These fast on/off cycles are poison to the battery and will destroy it in no time and could also lead of the premature death of the DSP. A stable 5V and a 1A supply current is essential when using external power.
Considering it's popularity, more people use the Mobius than any other similar, small camera so it can only be expected that more Mobius will suffer from heat issues than any other less popular model. However, there have been extremely few reports of the camera actually failing if used properly. Most reports are about people worrying
As we know, the heat issue is more critical when the camera is used in hot environments. If we respect this fact and ensure the camera is used in an environment where the surrounding temperature doesn't exceed 47°C (118°F) there should be no problem. This figure is what the developer recommends for a safe environment.

 

[iahim]

One question about low voltage: if I would use supercapacitor, I stop the engine (cut power) and camera stops immediately. Then, by mistake, I press the power button on the camera:
1. Camera will not start.
2. Camera will start, but it will shut-down immediately as some low voltage will appear instantly (supercapacitor is discharging very quick). This way there will be enough capacity preserved to keep the RTC.
3. Camera will start, it will consume instantly all capacity and all settings/RTC will be lost.

What do you think it will happen?

 

[jokiin]

not sure if they have any adjustments to the firmware to prevent it powering up without external power connected when using caps

 

[Necromancer]

ah, site didn't send me an email about replies.
good news, gonna order one more mobius and 2 caps!

about the adjustments, i believe they haven't thought about it.
if someone could forward to the developer to add an option into the configuration UI (for the super-caps mobius) to start and stop only when external power is supplied (ignore power button, as it won't work when pressing the buttons anyway due to no power), that would be great.
eeer... in second thought im not sure how possible it is. pressing the power button physically closes an electric circuit that requires/draws power.
i guess a quick check can be made against the parameters and stop the powering up of the camera and limiting the amount of charge lost, but guess its gonna loose some anyway.

 

[Isoprop]

ah, site didn't send me an email about replies.
good news, gonna order one more mobius and 2 caps!

about the adjustments, i believe they haven't thought about it.
if someone could forward to the developer to add an option into the configuration UI (for the super-caps mobius) to start and stop only when external power is supplied (ignore power button, as it won't work when pressing the buttons anyway due to no power), that would be great.
eeer... in second thought im not sure how possible it is. pressing the power button physically closes an electric circuit that requires/draws power.
i guess a quick check can be made against the parameters and stop the powering up of the camera and limiting the amount of charge lost, but guess its gonna loose some anyway.

Automatic start and stop when external power is connected/disconnected has been available in the firmware for ages! Perfect for the supercap.
You also have the option of using the power button, if you are so inclined.

 

[Necromancer]

Automatic start and stop when external power is connected/disconnected has been available in the firmware for ages! Perfect for the supercap.
You also have the option of using the power button, if you are so inclined.

talking about disabling the use of the power button so it won't drain the super cap and resetting the clock.

if someone could forward to the developer to add an option into the configuration UI (for the super-caps mobius) to start and stop only when external power is supplied (ignore power button, as it won't work when pressing the buttons anyway due to no power), that would be great.
eeer... in second thought im not sure how possible it is. pressing the power button physically closes an electric circuit that requires/draws power.
i guess a quick check can be made against the parameters and stop the powering up of the camera and limiting the amount of charge lost, but guess its gonna loose some anyway.

 

[murcod]

Isoprop, are you able to confirm that there is no form of over temperature shut down built into the Mobius. (I'm sure it's been mentioned previously, but there are posts above suggesting it does have some form of safety shutdown.)

 

[Necromancer]

There is no failsafe that will turn the camera off before its permanantly damaged.
See the mobius overheat discussion.

 

[murcod]

There is no failsafe that will turn the camera off before its permanantly damaged.
See the mobius overheat discussion.

Thanks, I was sure it had been said before.... can you find the reference? (I found it strange a couple of people were saying it did have protection on this thread.)

 

[jokiin]

I think there were some mixed messages about this, 47c has been quoted a few times but re-reading the times it was mentioned it was quoted as a safe operating temp, I still question the effectiveness of the heatsink, other cameras based on the same chipset don't use a heatsink and have no issues

 

[Isoprop]

I think there were some mixed messages about this, 47c has been quoted a few times but re-reading the times it was mentioned it was quoted as a safe operating temp, I still question the effectiveness of the heatsink, other cameras based on the same chipset don't use a heatsink and have no issues

I'm not surprised there have been no heat issues reported by users of other similar small cameras using the same DSP. They are not nearly as popular as the Mobius, they haven't been available for very long and I assume only a few have been sold so far.
You NEED a heatsink. Other cameras that use the same chipset WILL have a problem if they don't use a heatsink and are used for extended lengths of time in warm/hot environments. They may also experience problems with the CMOS sensor if they use a plastic body.
The 47°C is the safe environment temperature recommended by the developer, but that is already not a good temperature for the LiPo.
The small gap between the DSP and the heatsink could be optimized, IMO.

 

[jokiin]

I wasn't referring to the other small action cams (perhaps I wasn't clear), the same 96650 + AR0330 solution is already out there in several hundred thousand dashcams, it's a very popular solution right now and I don't recall anything in the way of complaints about overheating or even running excessively hot

I agree that in regards to heat the battery is of far greater concern, if I were to use one in a car on a regular basis the few extra dollars spent on the capacitors would be money well spent

 

[Necromancer]

Thanks, I was sure it had been said before.... can you find the reference? (I found it strange a couple of people were saying it did have protection on this thread.)

http://dashcamtalk.com/forum/threads/the-mobius-heat-issues.2392/page-5#post-36137
and if there was a failsafe that wouldn't happen
http://dashcamtalk.com/forum/threads/the-mobius-heat-issues.2392/#post-26566

and the existence of a failsafe mechanism is not mentioned anywhere (here, RCgroups, or seller sites).

 

[Isoprop]

I wasn't referring to the other small action cams (perhaps I wasn't clear), the same 96650 + AR0330 solution is already out there in several hundred thousand dashcams, it's a very popular solution right now and I don't recall anything in the way of complaints about overheating or even running excessively hot

I agree that in regards to heat the battery is of far greater concern, if I were to use one in a car on a regular basis the few extra dollars spent on the capacitors would be money well spent

I would think the compactness would be the major concern. I don't know the dashcams you are referring to, but I imagine they have more space inside the housing.
The Mobius developer has been concerned about excessive heat even before the first prototypes, so there must be a good reason. I am not aware of any failsafe mechanism built into the DSP, but who knows?
I'm sure there were also many dashcams based on the same DSP as used in the #11/#18/#16. My #11s would always quit working at around 32°C - 38°C when recording the whole day without any air circulation. They didn't melt though!

 

[Necromancer]

big dashcams might have an internal heatsink covered by the case and "invisible" from outside.
i highly doubt this DSP chip can work for more then several minutes without any type or form of heatsink. but im just guessing...