Add a battery to a USB Webcam?

So what I am doing is extending the cable of a webcam and the computer no longer recognize the Camera. So everything I have found suggests I use a power USB hub to give it the extra oofh needed to make the distance. But what I am doing makes that not possible because I will be outside far from any outlets. What I plan to do is place a battery on the camera is self and only transfer the data of USB. My thoughts were to connect a battery to the power lines of the USB cable but the Diagram says that red is DC, that's fine but the black is listed as a GROUND. That implies I couldn't just hook the negative the the black wire. Is this so? If it is how could I complete the circuit? 

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verence2 years ago

The voltage drop along a long USB cable is not your only problem. As the cable gets longer, the capacitance of the data lines gets higher. The higher the capacitance, the slower the data lines can be switched from low to high or vice versa. Therefore, USB can only drive a certain cable length. USB2 as your camera most probably needs is limited to 5m. It may work with longer cables, but that's outside the specification.

Get a camera with a network port (Ethernet) and can be powered via the network cable (Power-over-Ethernet). Distances up to 100m should be no problem.

Jayccob (author) 2 years ago

Ok, quick follow up. How do I marked as answered?

Jayccob (author) 2 years ago

Ok, guys thank you for your help. I have been researching the last three days and plus what you guys said I just broke down and bought an extender. Once again thank you.

Another part of why the camera isn't recognised is the very poor driver capability of the USB bus into the capacitance of the wires.

+1. If you intend long distance operation, you may need to use a wirelss webcam

Jayccob (author)  seandogue2 years ago

Normally I would completely agree but......

wireless webcams don't do well 40 ft under water or 40 ft down a squirrel hole.

Lol, I must have missed that part of the equation. As Steve notes, an extender is your best bet. Some will drive signals approximately the length of a football field or so, although I suspect they're not inexpensive. There are probably other models with less range (and less cost) than the industrial versions I'm thinking about.

Well USB isn't going to work on a 40 foot USB cable either....I think you can get USB/optical extenders, or you could try a USB isolator module, to see if it will give you extra oomph.

how far is this away from the computer?

before you add a battery i would check to see if you have shielded wire (has foil under the rubber on the outside) and if you don't try using shielded wire

Jayccob (author)  bravoechonovember12 years ago

The wire is shielded and ,your going to hate me for this, I extended the cable to one of two different hook ups:

1. ~65 ft of 22 gauge wire (I dont believe it is shielded)

2. ~40 ft of CAT5 cable.

After some looking around this seems to be one of my options:


oh ok good luck!!

USB 2.0 specs for 2.0 state a maximum cable lenght of 1.5m.

USB 3.0 specs allow up to 5m but I don't know any webcam that actually fully uses USB 3.0.

I did some extensive tests on different types of cables to be used for charging purposes only.

The best I could find for this was double shielded S-VHS cable.

Even with that I was only able to get a max of 1A charge with a lenght over 1.6m.
At 1.2m I was getting 1.4A while at 1.8m there was no charging at all.

And mind you while charging there is no data required, only a static voltage on the data lines.

As said by others a WiFi cam is your best option or if picture quality is is more important use a video grabber and a normal video cam.

Normal video cable can be up to 20m without significant loss of quality.

WiFi cams often offer a pan tilt function which can be useful too.

But no chance with USB cams ove long distance.