Author Topic: Cameras In Hot Car  (Read 5755 times)
toomanybulbs
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Re: Cameras In Hot Car « Reply #15 on: September 23, 2016, 10:04:44 PM » Author: toomanybulbs
all the parts on a board have to withstand solder melting temps.the battery is the item of concern.
li-ion degrades fastest in high temps and high state of charge.
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Ash
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Re: Cameras In Hot Car « Reply #16 on: September 24, 2016, 02:33:01 AM » Author: Ash
They withstand solder melting temps for a few seconds once in their lifetime. For long periods the acceptable temperature is orders of magnitude lower
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wattMaster
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Re: Cameras In Hot Car « Reply #17 on: September 24, 2016, 10:05:26 AM » Author: wattMaster
I would also be concerned about the flash memory having faster degradation in high heat.I saw in microcontroller datasheets that the data has a lower data retention life in high heat.
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toomanybulbs
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Re: Cameras In Hot Car « Reply #18 on: September 24, 2016, 10:28:46 AM » Author: toomanybulbs
by the time this slightly increased degradation occurs you wont care about that camera any more.
the battery and the possibility of theft are the only ones worth mentioning.
I would also be concerned about the flash memory having faster degradation in high heat.I saw in microcontroller datasheets that the data has a lower data retention life in high heat.
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wattMaster
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Re: Cameras In Hot Car « Reply #19 on: September 24, 2016, 01:08:01 PM » Author: wattMaster
Something I try is to blast the air conditioned air onto whatever will be left in the car.
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Ash
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Re: Cameras In Hot Car « Reply #20 on: September 24, 2016, 01:16:11 PM » Author: Ash
Are you really sure about the image sensor ? I have read there is some issue with CCTV cameras that work under direct sunlight (and not aimed into the sun ofcourse), where the cameras overheat when the sun heats the enclosure. I dont know whether the problem is the image sensor or some processing chip (so maybe there is problem only with the heat of the sun and of the camera's own power dissipation combined, but not with the sun on an inactive camera)
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Medved
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Re: Cameras In Hot Car « Reply #21 on: September 24, 2016, 02:26:13 PM » Author: Medved
The only problems with image sensors and heat is, the sensing cells have higher dark current (so higher dark noise; in fact it is just the temperature dependence of a diode leakage, nothing else) when hot. But that is usually not any problem, as when there is hot, it means usually enough light as well. But it is only a thing of worse performance at hot, once it cools back down, the sensitivity is back...

So really the only thing that really degrades there is the battery. And it may be so, it even catches fire (I think well known problem with LiIon/LiPoly cells).
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Ash
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Re: Cameras In Hot Car « Reply #22 on: September 24, 2016, 03:42:06 PM » Author: Ash
For exactly this reason, i wonder why then is any concern about it at all in the CCTV field ? I'd assume that the problem is some cumulative permanent damage to the camera, and not an effect that have no meaning when there is enough light anyway
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wattMaster
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Re: Cameras In Hot Car « Reply #23 on: September 24, 2016, 03:52:13 PM » Author: wattMaster
Maybe it's the reason almost all video you see from CCTV cameras looks like it came from a cheap webcam.
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Ash
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Re: Cameras In Hot Car « Reply #24 on: September 24, 2016, 04:01:00 PM » Author: Ash
Thats because most CCTV cameras indeed are cheap cameras inside, the biggest difference being the enclosure, and sometimes mehanical system to move in/out the IR filter for night vision mode, while in webcams its either permanently there or missing altogether
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wattMaster
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Re: Cameras In Hot Car « Reply #25 on: September 24, 2016, 04:03:20 PM » Author: wattMaster
Thats because most CCTV cameras indeed are cheap cameras inside, the biggest difference being the enclosure, and sometimes mehanical system to move in/out the IR filter for night vision mode, while in webcams its either permanently there or missing altogether
But that doesn't explain why a lot of them cost so much.
You may as well make your own webcam security camera.
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Ash
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Re: Cameras In Hot Car « Reply #26 on: September 24, 2016, 04:26:34 PM » Author: Ash
They cost because they have more durable enclosures, some have also the mentioned IR filter switching system, and generally better QA even if the actual chip is the same. Also probably just bigger markup in the industry..

I have allready put together a CCTV system out of old PC and few USB cameras in the not so far past, and it got the job done (found the "culprit" to some vandalism problems), at no cost except electricity (being IT as job and as second hobby to lighting/electricity, i always have PCs, big harddrive, and old webcams/USB cables/etc laying around)
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Mercurylamps
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Re: Cameras In Hot Car « Reply #27 on: September 24, 2016, 07:24:31 PM » Author: Mercurylamps
Something I try is to blast the air conditioned air onto whatever will be left in the car.

A motor vehicle's air conditioning system works by a A/C compressor driven by belt from the engine. It won't work while the car is off unless if you leave a car running all the time to keep the camera cool? ???
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Medved
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Re: Cameras In Hot Car « Reply #28 on: September 24, 2016, 10:33:47 PM » Author: Medved
For exactly this reason, i wonder why then is any concern about it at all in the CCTV field ? I'd assume that the problem is some cumulative permanent damage to the camera, and not an effect that have no meaning when there is enough light anyway

I guess this is the generic problem with high temperatures and an electronic reliability.
The camera is in first place an electronic device, exposed to quite severe heat from the sun and expected to work 24/7 for years, that means 100+khours. Plus there are mechanical components, which should work smoothly over all the temperature ranges, with
So I don't think that has anything common with the sensor at all, just the fact it is an electronic and mechanical device exposed to elements is enough to be careful with casing design.


Maybe it's the reason almost all video you see from CCTV cameras looks like it came from a cheap webcam.

All CCTV cameras have very high resolution, but quite wide angle of capture, the videos are just cropped pieces of the full image the cameras see.
Plus for the CCTV nobody really needs exact color rendering, other parameters (light intensity dynamic range, resolution, the "night vision" capability, all that combined with high reliability and reasonable life time with minimum maintenance that includes minimum lens and cover cleaning...) are way more important. And as with any other engineering, you have to make some compromises, can never have all.
Plus many published videos are officially distorted to keep the real camera capabilities on the given places that much of a public information.
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Re: Cameras In Hot Car « Reply #29 on: September 29, 2016, 02:22:28 PM » Author: Ash
The low end old CCTV cameras genuinely can do about as much as 640x480.. And many of the videos that were caught on camera recently, were captured by ~10 year old cameras
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