On EBay, I can find small devices to measure power output of a powerbank or computer usb port.
How about a device to measure the power transmitted over a normal (non quick charge) usb/micro usb cable?
Reason is, I have found some of the cables are taking longer times to charge my devices, and I wanted to remove the one that is not worth keeping
It actually tells you the current going into the battery. It can't account for use by the device itself.
It's a good app but not perfect.
You can compare cables, but only if the device is doing the same thing each time. Eg. Screen brightness the same.
Yep that's correct, but if the cable is as poor as is being suggested, it should be pretty obvious if the variance is reasonably large in the same environment.
If you plug in the cables sequentially, it should give a rough estimate.
Depending on how much effort you want to go to you can either make your own test wire that lets you put in a multimeter, or use some adapters that you plug in those USB measuring devices.
https://www.ebay.com.au/itm/2-PCS-Mini-USB-2-0-Female-to-Mic…
That said if you're looking for dud cables, the software would be good enough imo. Run the battery down and just run each cable for like 5 minutes. The one that is slow should be pretty obvious.
To get an estimate, find out the gauge of the wire used in your USB cable and check the tables in this article. To get a better answer you can measure the actual resistance of the wires in your USB cable with this circuit and calculate as the article explained.
Isn't that the point of the device? To measure Volts and Amps transmitted in the first place? I think it's more than just your usb cable that's affecting power transmitted.
Just swap the cable out between your device and power bank and measure
You have answered yourself in your post. Just throw out the cable taking the longest time to charge your device. I would have thought that would have been obvious…
I have around 20 cables or so, testing it one by one rather time consuming for me. Thus the reason I am looking for a small device
To my knowledge, there does not seem to be any device available commercially. To test your cables you will need to know a little bit about circuits. For example, you will need a device that does not measure power, but amps and voltage such as this - https://www.ozbargain.com.au/node/341743 and some adapters. A measurement of the voltage drop at the end of the subject cable at same current(1.0A and above) between all the cables is what your after.
That seems a little bit over the top, I suggest testing cables using the charging time, til you get to say 5 good ones and throw the rest out.
I use Ampere. Is available for free on Google Play. Tells you the amount of power going through the cable.
https://play.google.com/store/apps/details?id=com.gombosdev.…