Supercaps / Capacitors installation DIY project and Tests. B40 ( A118 )

niko

niko

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This is DIY project. Act on your own risk !!!

So, few week ago I have decided to test and see if B40 can work with Supercaps.
I was using Taiwanese powerful Supercaps YEC 10F 2.7V ( 2pcs gives total 5F 5.4V )


Supercaps Test 1



Supercaps Test 2


It saves last file after power is disconnected.
Below I am adding two raw / original video files you saw from Supercaps Test 2 video, - you can see that they are not corrupted, I was able to playback them on B40 and also copy to PC. All worked fine.

VIDEOS recorded with Capacitors.

As you saw from Youtube video "Supercaps Test 2", the last file did show on playback mode as "error", but when exit from playback mode menu and then go back, - then it played this last file. This was also with all other further tests I have done at home. It's kinda shows error on the screen, but file is not corrupted and can be played and copied to PC and play on PC/laptop as well.
Those are all nice and positive tests results from my day 1 testsings.

Now back to reality.
After nearly 1 week of testing it in real life, driving-recording with supercaps version every day, I was checking last file on PC, - in all cases last files had full data ( Mb ), but in almost half cases those files could not play on PC ( laptop ) despite data was displaying as a full value of Mb per video length ( 100Mb, 150Mb, ... etc ). In the past I had few dashcams with faulty batteries where last files was not properly saved due to faulty battery, - there was almost no data, only 44kb. But its strange that B40 non-readable files have full value of data, but still can not play ( I have all latest codecs ). In other half cases last files had also same full value of Mb per length, but they were readable same way as those two raw / original video files I shared with you above.
Time, date and other settings holds about 3-4 days. After that they reset to factory settings.

The only two ways to guarantee to save last file 100% with no error, is
1. - to chose loop recording 1 minute and to hardwire power to time cut-off delay source, like interior reading lights which shots down in most cars 1-3 minutes after ignition is off.
2. - manually stop recording and only then switch off ignition, but this is not a practical way and not solution to proper work of capacitor based daschamera.


My conclusions:

B40 can work with supercaps, but firmware should be specially adopted by developer in order to always save properly last files, because at the moment it is like a lottery: some time saves, some time not.

Anyway, this project is for just out of curiosity to see if I can "ruin" another dashcams with my silly experiments :). This time I got lucky, B40 still works fine.


Testing size / fitments or supercaps.

a1.jpg


Unsoldering stock battery 3-wire chip.

a2.jpg


Assembly of supercaps.

a3.jpg


Soldering supercaps to stock battery 3-wire chip.

a4.jpg


Ready

a5.jpg


Capton tape

a6.jpg


Wrapped into capton tape.

a7.jpg


Need to cut those 3 "ribs" in order to fit supercaps

a8.jpg


Cutting "ribs"

a9.jpg


Ready.

a10.jpg
 
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This is what I think is happening: When the firmware creates a file on the card it allocates space for the whole file. After the space is allocated is begins filling the file with data. If the power last for all the data to be written then the file will be readable. However, if the power dies before the entire file is written then the application will see a partially written file that's makes no sense. The file size with be correct but part of the data will be invalid, zeros, FF's (Hex), or random numbers, according to driver firmware. You may be able to verify this but viewing the bad files with a Hex file editor. I think this is what you are seeing. If your file size is 5 minutes and the power is dropping out in 2.5 minutes, half your ending files will not be readable, depending how much of the file was written before power was turned off. One solution would be to increase the size of the caps to increase power down time. Probably not feasible. If the display was on during power down, firmware could turn it off along with the leds to increase power down time. Just my two cents, hope it has been helpful.
 
wrdjr20 said:
This is what I think is happening: When the firmware creates a file on the card it allocates space for the whole file. After the space is allocated is begins filling the file with data. If the power last for all the data to be written then the file will be readable. However, if the power dies before the entire file is written then the application will see a partially written file that's makes no sense. The file size with be correct but part of the data will be invalid, zeros, FF's (Hex), or random numbers, according to driver firmware. You may be able to verify this but viewing the bad files with a Hex file editor. I think this is what you are seeing. If your file size is 5 minutes and the power is dropping out in 2.5 minutes, half your ending files will not be readable, depending how much of the file was written before power was turned off. One solution would be to increase the size of the caps to increase power down time. Probably not feasible. If the display was on during power down, firmware could turn it off along with the leds to increase power down time. Just my two cents, hope it has been helpful.
Click to expand...

about shorter loop recording I have already added suggestion earlier ( 1 min files ). All this time I was driving-recording with 3min loop. Will try 1 min loop soon and see how it works.
Bigger supercaps unfort. does not fit into available space under shell. Those 10F are the maximum biggest can fit without major modification ( only 3 "ribs" needed to remove as seen from photos ).
Panorama uses similar 10F supercaps ( as well as many other Korean capacitor based dashcams ) and they all saving last file, even 5 min. files, so size of 10F is plenty.
Mobius uses twice weaker 5F supercaps ( 2.5F combined ) and it also saves last video file, but its due to FW changes to work with supercaps.
So I guess best is to wait till factory model with supercaps and proper firmware will be relased.
 
I'm new to dashcams and know nothing about this cam. But, have an EE background with many years of embedded controls experience. Some IC's are current hog's while others draw very little current. The only difference is a letter at the end of the part number and the cost of the IC. So comparing one dashcam to another can be like comparing apples to oranges. It could be that this camera just draws more current and the only way this can be fixed is to build a low power version. This may require a redesign depending on whether low power pin compatible replacement parts are available.

The question I have is why do we need battery backup anyway? Other than for the real time chip. Most cell phones can take pictures on vehicle damage. If I were to design a dash can, I would use two 12v power wires, one to switch the camera on an off using the ignition switch power, and the other supplying power all the time to allow the camera to shut down slowly or enter park mode. I know there might be that time when an accident causes the loss of battery power, but this can be resolved by adding super capacitors in the external 5v regulator circuit supplying continuous power to the dash cam, where size is not as much an issue. With the know how, one might be able to modify an existing camera to use this method, but it would require disconnecting the cameras internal battery charging output by cutting a trace or removing a component, and adding another wire to an existing connector or installing another connector. Just thinking out loud.
 
That's good to know, maybe we will see more in the future. It has worked well in engine controllers for storing OBDII error codes and other engine related data. In dash cams it could be cost prohibitive on lower cost cameras, but makes since on higher quality camera's. Enough said, back to the thread.

Niko,
You are doing great work in this forum, I do not know where you find the time, but it is appreciated.
 
Niko,
It would be useful to get some current measurements on dashcam's that work with super capacitors and the amount of capacitance used. A pattern should emerge of how much capacitance is need for a given current requirement. Then one can measure the current drawn by a dashcam to determine whether a super capacitor will work in the camera. To make the measurement the battery must be fully charges and the camera must be recording video files with the display off. An interesting starting point would be measuring the current demand of your Möbius vs the B40, and see if the B40 is drawing more than twice (3x) the current. A 1amp current range on a volt meter should work if the capacitors are fully charged. If the B40 is not drawing 3 or more times the current then something else is causing your file corruption.
 
If I understand you correctly then the Möbius is not concerned with completing the last file it was in the middle of writing, it deletes it and shuts down. If that is the case, the B40 can do the same thing with the firmware change, maybe that was what Niko was suggesting earlier. Makes since, but may not be desirable if power is loss durning an accident. However it will avoid end file corruption and reduce the need for larger capacitors. So measuring the Möbius current would not provide any useful data. I don't get the 20 seconds shutdown on the B40, it is not enough to complete a file write before shuting down in most cases. There is a lot I need to learn about these dashcams.
 
wrdjr20 said:
If I understand you correctly then the Möbius is not concerned with completing the last file it was in the middle of writing, it deletes it and shuts down.
Click to expand...

Mobius does save the last file when power is cut. I've been using mine for months with no failures.
 
No, regardless of how long they are programmed to run for after losing power they still need to close the last file correctly before power off, this process is very quick
 
So we are not talking about the current 5 minute buffer that only has say 30 seconds of accquired data in it. We are talking about the privious 5 minute buffer full of data that still needs to be written to a file on the card. Yes that can happen very fast. Here I was thinking that the camera was trying to save the current buffer that is only partially full and will require another 4 1/2 minutes to aquire the rest of the data. Hopefully, I am now on the same page as you. A 20 second shutdown would allow it to capture 10 seconds before and 10 seconds after an accident and still save the event before shutdown even if power is lost and still have time to perform a clean shutdown.
 
jokiin said:
No, regardless of how long they are programmed to run for after losing power they still need to close the last file correctly before power off, this process is very quick
Click to expand...
Are you also saying that it will save even the 30 seconds of a 5 buffer as a 30 second file? Makes since. Does the firmware use circular buffers or does it just write directly to the card?
 
There's no buffer in most cameras, the data is written real time, wherever it's at when shutdown commences is what you get
 
Makes since now, a file needs to be closed properly. I have written such code hundreds of times, I don't know why I was trying to read more into this. I hope I am not getting you into any trouble, I am not trying to get you to review any trade secrets, just trying to understand the shutdown process.

And, Niko, sorry if I hijacked your thread, just trying to make since with what is going on and any possible solutions.

Thanks all. I need to get some sleep, its going on 3am here and I need to get up at 7am.
 
wrdjr20 said:
Makes since now, a file needs to be closed properly. I have written such code hundreds of times, I don't know why I was trying to read more into this. I hope I am not getting you into any trouble, I am not trying to get you to review any trade secrets, just trying to understand the shutdown process.

And, Niko, sorry if I hijacked your thread, just trying to make since with what is going on and any possible solutions.

Thanks all. I need to get some sleep, its going on 3am here and I need to get up at 7am.
Click to expand...


Oh noo, don't worry about high-jacking or about "trade secret"-stuff.
It's very good that we are discussing here more technical stuff, so others ( me also ) can understand more deeply technology, hardware, firmware etc., - thats why this place is called FORUM ;)
So, keep on asking questions and sharing your opinions. Its better to ask / write ( even silly questions / replays, - I do it also some time ), then not to ask / write at all !
 
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Where I got carried away here is trying to compare this to firmware development work I did I in the past which had nothing to do with dashcams. Need to keep focused on dashcam requirements. The Möbius was not designed for dashcam use, I have two, one for a bike headcam, another for a rc helicopter can. So their power down requirements are different and are designed to run off a self contained battery for extended periods. The dashcam needs to be able to record pass a loss of external power, as in the case of an accident and then shutdown cleanly. The amount of power down time is determined by the dashcam designers. Some may shutdown quickly, others may may continue recording 10 or more seconds of video before shouting down. The D40 is one of these, which Jokiin says takes 20 seconds to power down. It would take one large super capacitor to do that, unless the shutdown time was reduced. Knowing the shutdown time, the current requirement, and the minimum dropout voltage for a dashcam, we could calculate the minimum capacitance needed to allow for clean shutdown. Designers are unlikely to provide such information, and measuring on the bench takes as much time as connecting a capacitor and seeing if it will work. And determining the dropout voltage requires equipment most do not have or looking up the specs on each IC and the CCD. I would think that the dropout voltage is simular for most dashcams. I'm just use to doing the engineering up front, and avoiding the trial and error time consuming approach.
 
These particular products were designed with batteries in mind, möbius included so whether or not they can run ok using capacitors is part firmware, part luck

The B40 mainboard needs a redesign to run capacitors, it's not just a firmware thing, not out of the question though ;)
 
Here are the steps to get the data we need:
1. Disconnect the positive side of the fully charged internal battery.
2. Connect a current meter positive lead to battery and negative lead to board where battery positive lead was connected. To measure battery discharge current.
3. Connect a voltmeter to battery positive and ground, to measure discharge voltage.
4. Power camera up with external supply and start logging data.
5. After negative charge current drops to near zero, disconnect power cable and start stop watch.
6. Record the discharge current of the battery.
7. Record the battery voltage and the time when the current begins to drop off abruptly.
8. It is important to measurements at the beginning of the current dropout because battery voltage will bounce up some after electronics shutdown.

Now here is the problem. Digital volt and current meters will not capture these values because of slow update times, Analog current and volt meters will only give ballpark values. A digital storage scope with a voltage and analog probe will allow us to capture the data we need. I have two, but that does not help you much. When my GT680 is delivered I can get some baseline measurements on it. I can measure the current and dropout voltage on the Mobius also.
 
jokiin said:
These particular products were designed with batteries in mind, möbius included so whether or not they can run ok using capacitors is part firmware, part luck

The B40 mainboard needs a redesign to run capacitors, it's not just a firmware thing, not out of the question though ;)
Click to expand...

Thanks, that answers our question on the B40.
 
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