Power supply 3-way adapter

[MJDaniels]

Newbie questions here,
To minimize threading of dash cam power cabling, I hear many are using the powered circuit that a rear-view mirror in their vehicle is powered by. They install a commercially available splitter style 3-way adapter like the one pictured below, with one leg connected to the vehicle’s powered circuit, another leg then connected to a rear-view mirror that is normally powered, and the 3rd leg is an open USB connector for use in providing power for the dash cam. This is instead of threading a cable to the dash cam from a fuse block or a cigarette lighter. By doing this, they bring a power source and connector close to the dash cam, where they can then connect the camera with a short USB cable.

This seems efficient and makes for a nice, neat package + no threading of cable. However, this means that the USB connector is then 12V. I'm not sure how feasible this method is, there is no real space for a 12V-5V step-down device, and I think most dash cams are not dual voltage and want only 5V to operate.

My questions:
- If you were to apply 12V directly to the dash cam, wouldn’t you fry the dash cam?
- Are there dash cams available that will take 12V input directly into the unit?
-What am I missing? Does anyone have any experience with this that they would be willing to share?

Thanks in advance.

 

[kamkar]

Welcome to the forum MJDaniels.

Yes most dashcams are 5 V hence why the use one or another USB plug, but mostly USB C these days.
There are 12 V cameras but they are rare these days, but some of the Korean brands have done that, normally these will then use a small barrel plug to go into the camera.

There is a few ways to go about this i feel ( never done it )
1: the hard wire kits for many cameras have a little box on the wire, in there is the low voltage cut off, which most often you adjust on a 4 position slide switch ( 11.8 - 12.0 - 12.2 - 12.4 volts )
You will also find the coverversion from the 12 V you feed in to the 5 V that go to the camera.

I an not sure if there are any space savings or if its needed, but the box are not super large, but maybe if you removed the plastic housing and put a piece of heat shring tube around the PCB and components on it to prevent shorts, you could make it even smaller.

2. The normal power supply, here the 12 to 5 V coverversion often go on in the plug that insert in the 12 V socket in the dash, again here stripping away the plastic housing, things could be made much smaller, again you want to do something to prevent the board shorting out on something, and securing the wires going into and out of the unit.

3: going for something premade like you seem to have been looking at, some people have done this in here but not very often, but as i understand it you can get redumade wire harnesses for various car brand / models, and i assume there will be a step down to the 5 V for USB cameras, like there appear to be in the pic you have found.

The thing in your picture, it look to have a 12 to 5 volt converter in that black thing on the end, to me it look like a CPB inside some heat shring tube and a USB A plug in the end like we know from our PC, so all you need is a short USB wire with USB A in one and and the male USB C you probably need in the other end.

The hard wire kits though, to be able to use parking guard features you need to wire in 3 wires on most brands today, a +12 V always on and a +12 V ACC and then ground of course, but as i understand you can just wire both +12 V wires to a ACC circuit, and then the camera will cone on and off with the car, just you will not have the parking guard features then.

The Step down thing, it do need to have enough power ( 2 - 3 A ) CUZ if a dashcam can not draw enough power it will behave erratic or worst case not boot at all, but most often it will just be erratic behaving.

 

[kamkar]

O i forgot to write, if you use a hard wire kit, you must get one made for the brand / model of camera you have, there are generic ones but the days of those are long gone today.

also the hard wire kits, they often have long wires either side of the box on the wire, thats not much problem with the 12 V side, those you can just cut down to the last 2-3 inches, the bigger problem is the USB / 5 V side of the little box, there you most often find 2 - 3 Meters of wire so you can route it neatly around your headliner / a piller and down under the dashboard.
And shortening that 5 V wire down even if it do not have the full wire count of a USB data cable then it is still a few tiny wirees you have to work with, it is entirely doable i feel but you need to have some tinkering skills and a soldering irom + whatever else you need.

So the ready made things you have been looking at, is probably the best solution, so all you would need is a short USB wire from the 5 V step down thing to the camera.


Picture of a Viofo brand hard wire kit.

 

[kamkar]

More forgetfulness from me ( 4 AM here ) going the DIY route, well unlike the plug in thing you have found, you will have to identify wires at the overhead lighting fixture, and some how / way tap into those, so a lot of work indeed.

I prefer installing and routing the wires normally along the front of the headliner and then down the A pillar behind the plastic trim there, as a long time addict, i can pretty much install a dashcam blindfolded in 20 minutes or so in my car, but only as i have 12 V plugs ready to go in my glove box, it would of course not be hard wire as messing with the fuse box are a whole other thing,,,, well compared to just ramming a 12 V plug as we know it into a socket.

I better hit the hay now, going to the range tomorrow to see if my friend got his new tou set up, and if it shoot as good as my 10 X more expensive toy,,,, i hope not.

 

[MJDaniels]

@kamkar
A pleasure to meet you!
Thank you very much for your detailed explanations and fully answering my questions. It is very much appreciated.

I've gone back and re-read the specs on that adapter shown in my post. You are correct, it is 5V/2A out of the USB end. Not sure how I missed that but thanks to you, I now know much more about it.

My next research project is to determine if I can use a power bank for using parking guard features and if so, which one for the Viofo A139 Pro-2ch or the A229 Duo. I haven't actually bought a dash cam yet, and never owned one, but with more and more crazy drivers out there, the time has come for me buy a unit.

Thanks again!

 

[kamkar]

Most dashcams as long as they get power, if nothing happen on the G-sensor, they will change to parking guard.
It is not super good to have the camera record regular " full blown " video as this generate the max heat, that is why parking guard in dashcams use things like a lower bitrate or time lapse to generate less heat internal, and so should be able to last longer in a car parked in the sun, CUZ as you know a car can get blast furnace hot then, and all electronics have a upper heat limit, and when a dashcam hit that it will shut down to save itself from a heat death.

Also i am personally not that happy about using power banks, the lipo batteries in then are quite volatile when it come to low or high temperatures, also why we recommend to stay clear of the dashcams that have a little lipo battery inside to handle emergency shut downs, here capacitors do much better.

I dont really have a need for parking guard as i have CCTV from my apartment on my parked car, so i just use that for 3 hours on the timer many systems have build in, this go easy on the little 55 Ah battery in my almost micro car.
I use low bitrate mode, this mean instead of recording using say 20 mbit, the camera only use 4 mbit, so instead of say 350 MB files ( 3 minute length ) a parking guard file are just 128 MB, and so there are room for many more.
This also record sound, in time lapse mode that do not happen as it would sound silly.

the bitrate are a image quality factor, so first time i tried i worried it might be too little if you park at the curb so maybe no plate captures, but my test show i did not have to worry.

There are dedicated dashcam power packs in case you do not want to use your car battery, though with low voltage cut off set to 12.2 or 12.4 you should not see a lead acid battery suffer.
The dedicated power packs use lifepo batteries which are a lot safer in the extremes of a car.
But of course it is a additional cost.