15' USB extensions are too long for the A129 Pro

[DAP]

There is too much resistance in the wires of a 15' extension cable for the A129 PRO to be reliable, I think even 10' might be too long.
The most visible symptom is the LCD display having unstable brightness. Other symptoms are having the camera randomly restart, or lock up. This might be the reason my A119 v2 was behaving badly too.
I wired my car with a 10' cable to the front location, and a 15' extension to the rear location (needed 12', but that length does not exist). I was having trouble with my rear location, so I swapped the front camera with the rear, the problem stayed with the rear.
I measured the voltage, with no load, I was getting 5.15V, but when I plugged the camera in, the voltage would fluctuate, sometimes dropping as low as 4.35V.
I have ordered some USB connectors, and when they arrive, I will wire just the power with lamp cord, that should be low enough resistance to make this work.

 

[Nigel]

Not sure if you are asking a question or not?
Also not sure of your setup, do you have two A129 Pro, for front and back? ("so I swapped the front camera with the rear ")

If you are powering a rear camera and you need an extension, extend the 12 volt cable, not the USB cable.

Also, the amount of voltage drop does depend partly on the power supply, not just the cable, so if you are not using a Viofo HK3 then you might consider a change of power source.

 

[DAP]

I'm not asking a question, I am posting information that I think would be helpful to others.

In answer to your questions:
I have two A129 pro cameras, one facing forward, and one facing to the rear. This let me swap cameras, and made it easier to identify the source of the issue.
Running 12V to the back of the car is not practical, there is no room for a power supply near the rear camera.
I currently have this power supply: https://www.amazon.com/gp/B0141Y4IRGhard wired to the back of the 12V cigarette lighter outlet in the center console of my car and mounted hidden inside the center console. This is the only place I have been able to find to safely tap 12V in a Tesla Model 3.
I have a 10' USB extension cable going to the front camera location, and a 15' USB extension cable going to the rear of the car. These are hidden in the head liner of the car, carefully placed so that they do not interfere with the passenger knee airbag or the side curtain air bags.
The only thing that is being powered by this power supply is the two A129 PRO cameras. I think 13A of 5V is sufficient to drive two A129 PRO cameras, so that leaves only the resistance of the wires to cause the voltage drop.

 

[Nigel]

The only thing that is being powered by this power supply is the two A129 PRO cameras. I think 13A of 5V is sufficient to drive two A129 PRO cameras, so that leaves only the resistance of the wires to cause the voltage drop.

Thanks for the explanation, it makes sense now.

Note that although 13A is far more than sufficient, a lot of these power supplies do allow the voltage to sag as the current draw increases, if you have a way of testing the output then check it under load, not saying it does, but your issue may be just as much the power supply as the cable.

 

[kamkar]

If you use a good quality USB wire you should be good, i used a cheap one and that resulted in a very unstable mobius camera at the end of it.
But i opted to tab into a fuse and put a 3 X 12 V socket in the back of the car ( well under the rear seat along side my baseball bat )
And then just use a "normal" lenght USB wire up the C pillar and over the headliner to the center of the rear window / hatch

Nice you got your alternative 4 channel setup un and running, those Teslas and other new cars can some times be painful to work with.

 

[DAP]

It is difficult to determine before purchase if a USB extension cable is good quality. They seldom mention the gauge of the wire they use. I plan to use lamp cord. I don't need four wires as all I need is power, and 14 gauge is MUCH larger in diameter than the 28 gauge that USB usually uses.

 

[DT MI]

I plan to use lamp cord.

Look into telephone wire. Heavier gauge than USB but smaller than lamp cord so it's easier to work with. I've made 30+ foot USB extensions for power with no problems, and I'm sure I could go much longer. Might not be good for data because of signal timing but really don't know enough about that to make an intelligent guess. I have gone 18 feet (15 + 3 foot extension) for a USB attached printer with no issues so the published 15' limit isn't a hard limit.

 

[DAP]

Look into telephone wire. Heavier gauge than USB but smaller than lamp cord so it's easier to work with. I've made 30+ foot USB extensions for power with no problems, and I'm sure I could go much longer. Might not be good for data because of signal timing but really don't know enough about that to make an intelligent guess. I have gone 18 feet (15 + 3 foot extension) for a USB attached printer with no issues so the published 15' limit isn't a hard limit.

I don't need the data lines in the car. Lamp cord is about the same diameter as USB or phone cables, but it has MUCH larger diameter wire. Where I have routed the cables, I could probably run five of these cables without trouble. Routing the cables is a real pain in my car though so the last thing I would want to do is route phone wire only to find that even that was insufficient, and then have to go do it again with lamp cord. With lamp cord, I should have a huge margin, and should get the job done the second time (usb extension cables being the first time). I've already made this mistake once, I'm not going to make this mistake a second time.

 

[DAP]

I have replaced the USB extender cables with power only cables built with lamp cord. The voltage only drops to 4.8V now. It will be a while before I know for sure if this fixes the rebooting problem I was having. Not driving much these days.
I was reminded how much I truly hate pulling wires through the body of a car.
The camera was pulling about 1A of current, so a drop of 5.15-4.8= .35V, V=IR, so the wire resistance is about .35/1 or 0.35 Ohms. About the only way to do better would be to run the 12V to the location and have a voltage regulator at the location of the camera, but I don't have space for that in the head liner.

 

[SawMaster]

The 15' limit on USB cables is due to cross-channel interference with data; it has nothing to do with powering. You will see voltage drop with most cables and with some cam's it's enough to cause issues. Look for 24ga cables using copper conductors. Avoid "CCA" type cables as these degrade over time, sometimes quickly. Monoprice is a good source of quality USB cables.

Phil

 

[jokiin]

move the power source closer to the camera is a better option, the voltage drop over a longer USB cover will just cause flaky behavior from the camera

 

[DAP]

move the power source closer to the camera is a better option, the voltage drop over a longer USB cover will just cause flaky behavior from the camera

There is only one viable place in a Tesla model 3 to tap into power. That is the back of the cigarette lighter outlet in the center console. The Tesla does not have a fuse box. The best place I have found to put the voltage regulator is in some dead space in front of the air filter in the center console. There is room to run wire to the camera locations from there, but not room for a voltage regulator anywhere near the cameras.
Some have attempted to tap into power at the 12V battery, but the car monitors the current from the battery, and can't monitor a direct tap of the battery. This has resulted in the car declaring the battery bad, and requiring a replacement.
The 12V outlet is a better choice for me as it is a switched outlet, and will shut off when the car is parked in my garage. I don't think it will shut off when parked elsewhere because I believe the Sentry mode will keep the car awake when parked elsewhere. This allows the cameras to go into parking mode when parked anywhere but by garage, and not waste power or camera memory by recording in my garage.

 

[kamkar]

That sentry mode make sense for dashcam parking mode, and something like that we will probably also see sooner or later.
Some people at least don't need parking mode at home, either cuz they have CCTV there or people cant easy get to the car as it is in a garage or on a fenced / gated property.

 

[ty04]

I’ve had dash cams and some other 12v outlets hooked directly to the 12v for 2 years now without a battery warning. Maybe if you never have the camera shut off it would cause a problem.