Dashcams in Vehicle with Stop/Start Function

If you do it on the 12v supply then the voltage drop over time is not a problem because the voltage regulator in the adaptor will continue to output 5v until the capacitor is nearly empty. Your problem then is that you can't use a cheap supercap since it needs 6 in series to cope with the 14.6v car voltage (maximum with alternator running).

But at higher voltage you need fewer Farads to store the same amount of energy, so you can use lower capacity capacitors, reducing the cost somewhat.

Add in the benefit that a good regulator will maintain 5V output even when the capacitors total has dropped far below 12V, and this could be a better solution. You will get a flat 5V output for a good time, and more of the stored energy will be usable. Might be bulkier though.

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My mistake. Thought you're getting a Hybrid with Stop/Start.:D
No problem. That may well be what I end up with - definitely some advantages with a hybrid.
 
...especially when you have a modern 1L turbo engine that takes little energy to start.
I think a vehicle the size of a Toyota Highlander/Honda Pilot/etc. will be a tad under powered. :(
 
But at higher voltage you need fewer Farads to store the same amount of energy, so you can use lower capacity capacitors, reducing the cost somewhat.

Add in the benefit that a good regulator will maintain 5V output even when the capacitors total has dropped far below 12V, and this could be a better solution. You will get a flat 5V output for a good time, and more of the stored energy will be usable. Might be bulkier though.

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If you use small super capacitors then you still need 6 and the cost mounts, remember that when you connect 6 in series you end up with 1/6 the number of Farads of the individual capacitors. If you use a conventional capacitor then you will need one of the larger ones and they are not cheap either, but you only need one + one diode and it is easy to connect up. We are only talking $10-15.
 
It's not going to be possible to fit it into the normal cigar lighter adaptor, too big.

If you have the space then you have a choice of doing it on the 5v or the 12v.

If you do it on the 5v then you can use a super capacitor at reasonable expense, however you need to check that the voltage is not above the 2.7v x 2 limit for 2 supercaps which some car adaptors do exceed at times and you still have the issue that as soon as the power goes the voltage will start to drop and the camera will probably shut down when you have only used 1/4 of the power in the supercaps, thus you need big supercaps.

If you do it on the 12v supply then the voltage drop over time is not a problem because the voltage regulator in the adaptor will continue to output 5v until the capacitor is nearly empty. Your problem then is that you can't use a cheap supercap since it needs 6 in series to cope with the 14.6v car voltage (maximum with alternator running). Probably best to use a conventional 16v or 24v capacitor, but then you need quite a big one to keep the camera going for any time. Plus you need to add a diode to prevent the power going back to drive the starter motor. Fairly easy to do, just a bit big and too expensive to make into a sellable product.

Still not convinced that it is needed with a decent AGM battery as found in cars with stop start, especially when you have a modern 1L turbo engine that takes little energy to start.

I wasn't suggesting that ancillary super-caps and any required electronics would ever fit inside a normal cigar laughter adapter. I was using the term "in-line" super-capacitors literally; something more along the lines of the photo below.

I would think a solution like this would be best approached from the 5V end of things rather than 12V but you make a good point about the 2.7 volt x 2 limit using two super-caps.The original idea however was to have an in-line 5V module that would sustain 5V to the camera for the brief periods when the 12V circuitry cuts out. While it might require bigger caps I don't see it requiring more than two of them.

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I wasn't suggesting that ancillary super-caps and any required electronics would ever fit inside a normal cigar laughter adapter. I was using the term "in-line" super-capacitors literally; something more along the lines of the photo below.

I would think a solution like this would be best approached from the 5V end of things rather than 12V but you make a good point about the 2.7 volt x 2 limit using two super-caps.The original idea however was to have an in-line 5V module that would sustain 5V to the camera for the brief periods when the 12V circuitry cuts out. While it might require bigger caps I don't see it requiring more than two of them.

View attachment 33060
Whatever size the capacitors, the 5v will still start to drop instantly the power is lost, so if it works or not depends on what voltage the camera decides to shut down at. A super capacitor camera is always going to shut down very early rather than try to keep going and so most of the energy in your additional capacitors will never be used.
 
Whatever size the capacitors, the 5v will still start to drop instantly the power is lost, so if it works or not depends on what voltage the camera decides to shut down at. A super capacitor camera is always going to shut down very early rather than try to keep going and so most of the energy in your additional capacitors will never be used.

I understand what you are getting at but I know that super capacitors are regularly used in many situations to bridge power gaps lasting from a few seconds to as much as few minutes. Isidor Buchmann of Battery University describes this as "similar to a flywheel". I suppose someone could design and build one of these and see if it really works or not. When I dabbled with installing external super-caps in a dash camera, the two 10F caps would keep it running for eight to ten seconds after power was shut off.

The other solution that's often been discussed here is the use of a delay timer between the 12V source and the camera's 5v adapter. They are a small and inexpensive solution that could also be installed "in-line".
 
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I understand what you are getting at but I know that super capacitors are regularly used in many situations to bridge power gaps lasting from a few seconds to as much as few minutes. Isidor Buchmann of Battery University describes this as "similar to a flywheel". I suppose someone could design and build one of these and see if it really works or not. When I dabbled with installing external super-caps in a dash camera, the two 10F caps would keep it running for eight to ten seconds after power was shut off.

The other solution that's often been discussed here is the use of a delay timer between the 12V source and the camera's 5v adapter. They are a small and inexpensive solution that could also be installed "in-line".
Your two 10F caps would have been on a camera designed for a lipo battery and capable of running until the battery was flat at around 3.0v, a supercap dashcam will deliberately shutdown when the supply voltage is below maybe 5.0v with most of the power still in the supercap whereas a cap on the 12v supply will be almost emptied before the camera shuts down.
 
Your two 10F caps would have been on a camera designed for a lipo battery and capable of running until the battery was flat at around 3.0v, a supercap dashcam will deliberately shutdown when the supply voltage is below maybe 5.0v with most of the power still in the supercap whereas a cap on the 12v supply will be almost emptied before the camera shuts down.

My experimentation was a different scenario than what is being proposed here.
 
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