V3 & V2 Voltage Drop Testing with USB Extension Cables

I have 4 V2 cameras mounted outside . I am using 10, 20 and 25 ft USB extension cords . I have been having issues with 2 of the V2 cameras that when connected outside I could not access the SD card videos and would get sometime no SD card .
I went to replace one of the V2s with a new V3 camera and it was often locking up and I would get the “Getting Video Data 3/3” . I also had issues with the Audio . Every time I would attempt to speak through the camera I would hear nothing but scratchy static and it would lock up and loose the connection .
The V3 would work fine connected to the standard Wyze USB cable and power supply
I quickly built a USB breakout box so that I could measure the amperage and voltage at the camera . I found that just 1 V2 or V3 cameras at the end of my 25ft USB extension was causing a significant voltage drop .
Below are some of the worse cases with 2 V2 cameras daisy chained .
See my YouTube video below for complete bench testing .
Wyze V2 and V3 Voltage Drop Testing with USB Extension Cables

Testing Data
USB Extension Testing Data
25 ft extension with one V2 Note 4.57 Volts
25 ft extension with 2 V2 daisy chained . Note 3.94 Volts
Wyze V2 and V3 Voltage Drop Testing with USB Extension Cables


The main issue is the size of the wire in the USB extension lines. Generally the supplied wire size is too small for longer runs as the overall resistance is too high which is the limiting factor.

I use longer lines for camera power but made modifications to reduce the overall line resistance. One solution is to simply use a larger wire size. A number 18 gauge door bell wire is one possibility. Leave a 8 inch pig tail on each USB connector. Then connect your run of 18 gauge wire between the two USB connectors for the main run.

Others have used a DC/DC power converter and use 12 to 24 VDC with the converter to supply 5 VDC at the camera.

Thank you for taking the time to test and publish these! Nothing particularly surprising but it’s good to see numbers to back up our experiences.

What would also be helpful is seeing the voltage to both cameras in a daisy chain. The slave one seems to get much less power.

Yep, completely expected results, but thank you for taking the time to perform the tests and document it.


Great Test! Thank you @mrgadget for publishing the results. Any chance of more V3 testing?

Then there is always these bad boyz. USB breakout: Rated Current: 8A, Wire Range: 28-16AWG
Doorbell wire is usu 16 ga. The older telephone Inside Wire was 22 ga, newer IW is 24-26 ga.

1 Like

Ohh, nice. Those look great for tinkering. I’ve torn apart too many USB cables.

1 Like