I don't know how your calculations came up with just 3 minutes stopped at traffic lights per 100 km of city driving, either..

My calculation was clear ....

Fact one ..."According to Argonne National Laboratory, a 2-litre car will use around 0.7 litres per hour with zero load." ..... so at traffic lights a car is consuming 0.7 liters /hr ... and this is what you save with auto stop (in reality slightly less because of starting inefficiencies , some times you will burn more gas with auto-stop if the engine turns off , and the lights immediately go green)...realistically on average 0.5l/hr.

From search average fuel consumption of 2 liter car is 10liters / 100km ....

So lets say you take a 50 km city journey speed average 50km/hr it takes 1Hr and consumes 5liters

If stopped at lights for an additional 1Hr , journey time 2 Hrs consumption is 5.5Liters ... and that gives your 10% saving with autostop !!!

Ridiculous !!! On a 2hr city drive you have to spend 1 hr stationary at lights to get a 10% saving!!!

Of course people who buy such a car will report high savings , they want to believe they made the right choice..

 

My calculation was clear ....

I still see nothing that indicates how you came up with the claim that in 100 km of city driving that you will only be stopped for three minutes at traffic lights.

Earlier today I went down into town. A total drive of 60.1 miles (97 km). Of that, 52 was on the highway, leaving just under 8 miles (about 13 km) of city driving. Out of curiosity, I timed how much time I was stopped at stop lights. At the 25 traffic lights I had to go through, I got stopped at 11 of them (and that's about par) for a total time stopped at lights that was just over 14 minutes (which works out to 110 minutes per 100 km of city driving). I didn't think to time the total time that it took to drive that 13 km route, but if I use your 50 km/hr figure it would come in at between 15 and 16 minutes. I don't know if that's right, but it's certainly in the ballpark. Which would mean that I spent very close to one minute stopped at a light for every minute of actual city diving.

 

The topic of this thread is use of a capacitor. Here's a novel approach: Since we're spending so much time at red lights, why not install a "Flux Capacitor" and just bypass time all together?! I think we've gotten a little off topic here folks.

 

I still see nothing that indicates how you came up with the claim that in 100 km of city driving that you will only be stopped for three minutes at traffic lights.

Earlier today I went down into town. A total drive of 60.1 miles (97 km). Of that, 52 was on the highway, leaving just under 8 miles (about 13 km) of city driving. Out of curiosity, I timed how much time I was stopped at stop lights. At the 25 traffic lights I had to go through, I got stopped at 11 of them (and that's about par) for a total time stopped at lights that was just over 14 minutes (which works out to 110 minutes per 100 km of city driving). I didn't think to time the total time that it took to drive that 13 km route, but if I use your 50 km/hr figure it would come in at between 15 and 16 minutes. I don't know if that's right, but it's certainly in the ballpark. Which would mean that I spent very close to one minute stopped at a light for every minute of actual city diving.

I’ve not actually recorded times but I have a high level of confidence that in my city I spend >20% of travel time stopped at traffic controls. It could be much higher depending on traffic conditions. In some places, commute time on the highway includes long periods of not moving.

 

@Yaakov Did you mention you have a dash cam? That should be a highly reliable way to determine travel time as well as amount of time stopped at a red light.

But I'm really trying to resist the urge to jump into the argument of saving fuel because that's just plain off topic to this thread.

 

@Yaakov Did you mention you have a dash cam? That should be a highly reliable way to determine travel time as well as amount of time stopped at a red light.

But I'm really trying to resist the urge to jump into the argument of saving fuel because that's just plain off topic to this thread.

I do, and yes, if I wanted to review the recordings that would be a good source. I’ll put it on the list... let’s see, it’s at position 2.5342E13. Wait, that cant be right. Stupid list.

 

I have finally found some time to create my circuit, First post explains hat I am trying to create, but I am not sure where to put the diode and in which direction of flow, or maybe I need 2 on each end. Would this be the correct diode to use? I need the capacitor to hold the voltage just for the camera, Without a diode, my entire car will draw off the capacitor when the engine restarts, I have to allow the capacitor to charge up but be isolated from the rest of the cars electrical section going to repost also in 12 volt thread
My circuit
.

 

This turned into a long post, but stay with me
So I found the fuse in the under hood fuse box, that controls the aux socket. It’s a Jcase fuse,
https://m.littelfuse.com/products/fuses/automotive-aftermarket-products/cartridge-fuses/jcase.aspx
I also found a circuit under the hood that is only live while key is on.
So I tried an experiment where I pulled the fuse out, the style of fuse allows me to use 2 female spade terminals to connect to the male terminals built into the fuse box, I ran the hot male terminal to a relay controlled by the for mentioned keyed powered wire and ran the relay return back to the fuse box, Just so you know that circuit does have an in line fuse to protect my aux power circuit.
Now my aux circuit is controlled by the relay so socket goes dead without the key on.
This is what I want.
Now I suggest you go back to my original post to get the whole story to understand my issue.
Anyways, with it hooked up like this the issue, with the image popping up on my screen every time it auto restarts no longer happens. So I figure I just use the under hood control wire to the relay to power my 12 volt to USB hub as it seems to not loose power with auto restart, Problem is the issue happens again. Scratches head
So can a relay hold the circuit for that 1 second the circuit losses voltage?
Anyways i’ve Solved my problem by putting the aux socket on a relay control
If I put a relay inline with my USB hub will it resolve my issue? Just wondering

 

It's starting to sound like you've come up with a better way of powering your cam. But it also sounds like you're still experiencing the same issue. Back in post 24 I mentioned the vehicle battery. You've made clear you have a new battery, just a few months old, but the problem still exists. I recommended checking voltages when the battery was at rest over night. New batteries can also be bad. I've seen it a few times in my 45 years of car experiences, seen it personally. Bad new batteries are possible.

Nevertheless, you seem to want to move forward with putting a diode and cap in line with the cam. That can work, but that can also experience issues. Since the interruption is oh so short, but long enough to trigger the video screen, I still think putting the cap on the 5 volt line is the way to go. Just my personal opinion, but I think it's a better solution. It's also possible the USB (actually a 5V power supply but I'll call it a USB) may be the culprit. Adding a cap on the 5V line will mean smaller components and easier installation than going with the diode, cap and relay.

The diagram below shows what I believe your initial approach was going to be, with the addition of the diode to block back draining of the cap. That will work of course. You've since mentioned a relay. That too will work. I believe my solution will also work. I think it will work better and more reliable. It may be the location where you're tapping into auto power is better than where it was initially, but may still be subject to line loss due to other equipment on that line demanding power simultaneously, Aside from a weak battery, that would be my second suspicious cause of the problem. Hence, regardless of where the power loss is coming from, putting the cap on the 5V line completely isolates the problem of shared loads on the line you've chosen to run your cam.

Have a look at the block diagram I've uploaded (below). It's similar to your proposal but I think it's a better approach.

 

Hi, I'm Henry and new to the forum, I am an automotive technician
Some may think this should be in the automotive thread, but I think I'll get better results here.
So, I installed a dash cam that is basically a bigger rear-view mirror, this:
https://www.amazon.ca/TOGUARD-Waterproof-170°Wide-G-Sensor-Detection/dp/B07DN8Q8Q6
It is powered by a USB that runs off the cars ACC plug(cig lighter), so 12-14 volts to (usb) A 5 volts converter.
It only runs while the ACC socket is powered, and the dash cam shuts down when acc socket is unpowered
What happens is when the dash cam initially turns on, there is a display in the mirror glass of what the cam is recording, then after 30 seconds that image turns off so you can use the rear-view as its intended for.
My 2017 Ford Escape is wired so the acc sockets are always powered on, so the cam would never shut down.
I bought a USB hardwire kit that only is only powered with key on, and it works great: This:
https://www.amazon.ca/SHISHUO-Dash-...+volt+kit&qid=1553553104&s=electronics&sr=1-5
So here's my problem;
My vehicle has a feature called Auto Start/Stop, basically when you stop with your foot on the brake pedal and vehicle is in gear( waiting at a stop light) the engine shuts off and will remain off until you lift your foot from the brake pedal or put it in park, then the engine automatically restarts and away you go.
What's happening is there must be a momentary voltage drop in the fuse panel when the engine auto re-starts and what happens is the recording image pops back on the display for the 30 seconds which is annoying and blocks my rear-view for that time.Bare in mind the cam is not actually performing a couple restart, just image pops up on the mirror.
It will not do this if I use the provided ACC plug, but I want to use the hardwire kit I installed so I don't have to keep unplugging and plugging in that ACC plug, I bought the hardwire kit so it is a " set it and forget it"
Would a capacitor in-line with the 12 volt feed hold the voltage momentarily while the vehicle re-starts? I know something greater than 15 volts is needed but, What rating of cap would you use?
Thanks

You are correct all the way around. A big fat capacitor across your power supply should cover a multitude of sins.

 

As I sit here considering my approach, a thought occurred to me: What happens when you shut down the car? The cap will hold a voltage for a few seconds. But as it provides cam power it dissipates its energy, meaning the 5V doesn't drop to 0V when power is lost, power drops from 5 to 4 to 3 to 2 to 1 to Zero volts. I'm wondering, now that I think of it, will that cause a problem for the cam. So after posting my diagram I'm wondering if maybe my approach might not be as good as I think.

 

As I sit here considering my approach, a thought occurred to me: What happens when you shut down the car? The cap will hold a voltage for a few seconds. But as it provides cam power it dissipates its energy, meaning the 5V doesn't drop to 0V when power is lost, power drops from 5 to 4 to 3 to 2 to 1 to Zero volts. I'm wondering, now that I think of it, will that cause a problem for the cam. So after posting my diagram I'm wondering if maybe my approach might not be as good as I think.

 

I think i’m going to stay with my current set-up, using a relay to control the aux cig plug and using the provided aux socket cable that came with the camera, there has to be the pull down circuits to lower the 12 volts to 5 volts built into the plug and perhaps a capacitor which is maybe why I don’t get the blip when using the cameras supplied cable. I also found a way to hide most of the cable.
The relay cuts power which in turn allows the camera to shut down.
As far as the car battery goes, there is a battery management system that monitors the battery health,
As a auto technician may self , I can see the battery health on the scanner. I know that if the calculated battery percentage goes below 80% the car no longer Auto stops, when the car is auto stopped there is electrical demands no longer being met because the alternator is no longer charging, so if I was close to 80% and the calculated % drops below 80% the car will restart automatically. That being said I can sit at a red light for 4-5 minutes and the engine remains off, I think I can say the car battery is not the issue.
Perhaps the USB thing I bought is cheap junk
Anyways i’ve Accomplished what I needed