Rear Dash Cam installation help please

[Harsh]

It's probably the length. 5 metres is little excessive for a hatchback, 3.5 - 4 metres should be enough. I can confirm that cables from Amazon Basics work well too.

 

[flip9]

Voltage drop is too much on a 5 metre run. Even with thick 22AWG usb cable, a typical 5.1v source will end up as 4.86v @ 500mA draw.

You can run a 12v cable to the back and put one of these in. Its nice to have USB ports for rear passengers too.

 

[Dashmellow]

The Monoprice cables are well made, shielded and are very moderately priced. You can buy them in different lengths with or without a ferrite bead. The beaded one is a slightly thicker AWG.

I use the 5 meter USB-A to mini-B for my rear cam in an extended cab pick-up. It is easier to route than the thicker ones with the ferrite bead and these have always worked well and been long term reliable. Voltage drop has generally not been an issue for most cameras I tried. This depends entirely on the particular camera and it is always best to go with the shortest cable run you can. Five meters is pretty much the max USB cable length you can get away with.

https://www.monoprice.com/product?c_id=103&cp_id=10303&cs_id=1030302&p_id=3898&seq=1&format=2

Monoprice will ship internationally, but you need to inquire for more info. (https://www.monoprice.com/help?pn=termsofuse#returns)

You can buy these cables on Amazon as well. (at higher prices than direct from Monoprice. Amazon will ship certain eligible items to 75 counties, so these cables may be eligible. https://www.amazon.com/gp/help/customer/display.html?nodeId=201117930

https://www.amazon.com/gp/B018RAW534

 

[DT MI]

Voltage drop is too much on a 5 metre run.....

Depending on the quality of the cables that may be the case but it's not an absolute truth. I'm currently running 2 SG9665GC cams (front and rear) both of which are receiving power through 15 foot USB cables plus an 18 inch right angle connector (works out to be almost exactly 5 meters).

 

[Agie]

thanks everyone for your replies, very much appreciate everyone's advice on the matter. When the cable i was using was plugged in (Ritmo brand) it did flicker on and off the screens on the Viofo camera, so probably a matter of voltage drops as everyone has said.

I will give the Monoprice cables a try, but as @flip9 has said the voltage drop, and i calculated the voltage drop with the Monoprice and it seems even worse --- only outputting 4.04V. Putting a 12V cable and outlet is not an option for me unfortunately.

 

[Rajagra]

You could halve the voltage drop by rewiring the cable at both ends so the unused data lines double up as power lines. I always think it's a shame that half of the cable you've paid for goes to waste. But that mod would be very messy and create likely points of failure.

Some people have mentioned USB cables designed for power only. I can only say good luck finding them, especially in longer lengths and the necessary gauge.

Edit > An alternative idea would be to hack off both ends of the (unusable) long USB cable and use it to carry 12V instead.

Sent from my tap-to-talk using Tapatalk

 

[DT MI]

To expand on this discussion a bit the cable length restriction has nothing to do with voltage (power) transmission but rather it's due to signal timing of the data transmission:

1. Why are there cable length limits, and what are they?

A: The cable length was limited by a cable delay spec of 26ns to allow for reflections to settle at the transmitter before the next bit was sent. Since USB uses source termination and voltage-mode drivers, this has to be the case, otherwise reflections can pile up and blow the driver. This does not mean the line voltage has fully settled by the end of the bit; with worst-case undertermination. However, there's been enough damping by the end of the bit that the reflection amplitude has been reduced to manageable levels. The low speed cable length was limited to 18ns to keep transmission line effects from impacting low speed signals.

The above taken from http://www.usb.org/developers/usbfaq#cab1

What has likely happened from a cable manufacturing perspective is since the USB specification limits the cable length for the reasons above there is no reason to make a cable capable of carrying voltage for a greater distance since to do that requires a lower numerical gauge (thicker) wire which increases cost.

I would suspect (and this is my opinion only) that it would be relatively easy to make a DIY power only cable using heavier gauge wire that could maintain proper voltage levels for much greater distances than 5 meters.

https://www.adafruit.com/products/1387?gclid=CK3Y8dCNuNACFdccgQodpZQDtQ

 

[flip9]

It would be much easier to bring the 12v closer to the camera and use a shorter USB cable.

All you need is a fuse tap and run 4mm auto cable through the floor channel to the back and terminate it to whatever plug you want, or even hook it up directly to the dashcams included power supply.

It should take 15mins to do and can be hidden from plain sight.

 

[Agie]

thanks guys again for the input, it all makes more sense now. I'll give the Monoprice cables a shot now, and if that doesn't work then will look into the 12V option.

 

[Lola]

Not sure you will find locally but if buying online have a look at monoprice @Dashmellow has used their cables with good results

monoprice has 15 feet cables for under a couple dollars. I've used their cables quite a lot without problems. They carry a lifetime guarantee. There is NO place cheaper!

 

[Agie]

monoprice has 15 feet cables for under a couple dollars. I've used their cables quite a lot without problems. They carry a lifetime guarantee. There is NO place cheaper!

thanks for the endorsement, ordered and just waiting now for it to arrive. Pumped.

 

[Agie]

Ok so here's my revised description of how i wired in the rear of the car:

"Pushed a couple of buttons down (after prying the roofliner down to access the gap inside) near where the cardboard of the roofliner exits the back of the hatchback (so i could push the yellow tongue through the roofspace). First I threaded the miniUSB cable from the car charger, around the front passenger floor as per the first dashcam I had and then up around the edges of the glovebox. From there I threaded the miniUSB wire up towards the A-pillar, following the line of the rubber weathershield and then through to the top of the B-pillar (and entrance to the roofliner section of the back of the car). Had to wire it this way, as the initial way of wiring it across the rubber weathershield on the ground meant I ran out of miniUSB wire.

From there I left the miniUSB wire and grabbed the yellow tongue and pushed it through the roofliner gap near the top of the B-pillar, towards the back of the car, and then walked around to the back of the car to check it had come through the roofliner. Then proceeded to tape the miniUSB wire in two places a bit of a distance from each other then pushed the yellow tongue in the direction of the back of the car. Then walked around again to pull it through when it reached the back of the roofliner."

The cable I received from Monoprice works fantastically, and both dashcams power on without issue. Thankyou heaps to everyone who has helped me on this thread here much appreciated and happy to have it all wired up now! Running a Viofo A119 up front and a Chupad D501 down back.

 

[Harsh]

As Amazon Export Sales have finally started shipping Monoprice cables to India. Ordered multiple Mini USB and Micro USB cables in 10 and 15 foot lengths. Now I can get rid of the shorter Amazon Basics cables with which an extension cable is required.