Contemplating Dashcam wiring

12V power (~1V lower than the always present 13V on pin 24) on pins 2 and 16 do a hard chop. They do not fade.

I'm going to assume that my cigarette lighter to USB cable into dashcam is similar with two wires.

Your explanation about using butt splice crimps is very clear. I might do that or solder.

 

Well this is a little distressing. I first soldered in wires to splice to the 12V and Gnd. Then I chopped the USB cable that has the mini usb connector going into the camera on one side, and the other side is a cigarette lighter plug going to the cigarette lighter socket. And I measured the voltage across the two wires in the cable, red and black. 5V red, 0V black, not 12V !!!!!!!

I wonder if the camera can step down the 12V to 5V?

Otherwise I have to do it. Of maybe solder the USB cable back together and solder the whole cigarette lighter adapter into the spliced wires that I have set up in the ceiling cable.

 

seems that the dashcam vendor on amazon answers questions so I've just asked about this there. I did see that they sell adapters.

also in browsing I see some suggestions to find 12V->5V converters among electronics junk collections.
Or build up a circuit with a voltage regulator chip and a few resistors and caps, and small heatsink.

Alternatively I could wire from the overhead connector where I've just spliced into it to get the 12V and 0V and attach those wires to the contacts on the lighter. It wouldn't be easy to solder to the contacts but I could drill very small holes in the contacts and tap into them, to get that lighter adapter back into the circuit.

 

Embarrassing to say but I look at the dates of my postings about this and it's been a year. Last summer I did buy a cheap 12VDC to 5VDC converter and it sat on a shelf until now. Today I took it out and tested it. I wired it into my overhead panel and could see that I was getting 5VDC out of the converter when I hit the Power button on the Prius but when I plug in the dashcam that needs 5V the dashcam didn't come on and the voltage dropped to 1V as measured at the output of the converter.

Another factor: to test if the converter was working, prior to hooking it up the car's wiring, I had a small trickle charger solar panel sitting out in the sun not plugged into anything. I hooked the converter and dashcam to the solar panel and the small panel was driving the camera at 5V. So I don't think the converter is being overloaded by the dashcam. I think the two lines on the 24pin connector of the Prius overhead can't handle the load, which is strange since it can't be much of a current draw.

 

I think the inverter is fine and the dashcam is not drawing an excessive amount of power. The inverter is rated for 15 watts (3A x 5Vdc). I doubt the dashcam draws much power.
When I drive the DC/DC converter and camera from two pins of the overhead panel that are delivering a 12V always on (even with the car's Power button off) the camera works. It shows a solid red LED to indicate charging and by default a blinking blue to show recording.
I can't seem to find a pin combo that allows me a 12V when the car is on and 0V when off.
Am I seeing this wrong? Do I want the dashcam to always be powered? It came with a cigarette lighter adapter and the cigarette socket is a switched socket so it seems that the design of the dashcam is designed to work that way. I was using it that way when I first got it. But maybe it is also designed to be charging from the car battery when the car is off and then come on to be recording when the car is moving and I could use it hooked to a solid 24/7 on?

 

That's what I found but on a different version of the overhead panel that uses a 24pin connector. I found pin 9 as GND and pin 24 as 12V always present. And yes, the 5V line that is switched dropped too far down when loaded with the dashcam.

Here are the amp numbers that I read when delivering current to the 12V to 5V converter:
140mA when the dashcam is on.
35mA when the dashcam is off and the red LED shows that the dashcam battery is charging.
30mA when the dashcam is off and the red LED is off. So it still draws power. 30mA is pretty low and probably shouldn't be a problem for battery drain for the short term. Other systems are also on while the car is off.

Does anybody have an estimate of how much power is being drawn from the 12V battery while a 2013 Prius is off?

 

That's why I'm asking how much the rest of the car is pulling from the battery while it is off. Is 30mA a lot in relation to the overall draw? If it is a 10th maybe I can live with that, but if it is half of what the car normally draws from the battery while not on then I agree, I don't need that hassle.

 

So that I'm not draining the battery when the car is off I decided to just try to neatly run a usb mini b cable on the top edge of the windshield, door post and under the glove compartment to the accessory plug USB adapter. I determined that a 10 ft cable should do it. So I've purchased that. (dashcam came with it but I already chopped that one up in my experiments. $5)