[Solved] Problem with data transfer using USB power lines (so no data lines)

Elwin Hammer Asks: Problem with data transfer using USB power lines (so no data lines)
i am new here to this community but i am not new to electronics. I do mostly try to solve my problems on my own and sometimes look it up using Google. But this time do have an issue that i am not able to resolve and hopefully someone here could help me and hopefully i am able to also help others here in this community.

Ok so i am using a Omnidots SWARM vibration sensor to measure vibrations on construction sides, works fine but i do need a battery from Omnidots in order to make it work off-grid and those batteries are quite expensive also break quite fast. that is why i am making my own battery pack with also more capacity so i have to visit the sites less often.

But these sensors also send the battery capacity live together with the sensor data to their online platform so i first thought that they used the USB-data lines to get the data form the battery (since the sensor is powered using a Micro-USB cable). But when i opend up the case of the original battery, it only had 2 wires (USB 5V + and USB – ), so no datalines.

I tried to use my oscilloscope to get some image but had some hard time to get a good reading because i did noticed some difference but it was not much. It seems that it goes between 5V and ~4,7V (square wave) And the lower the battery capacity, the longer it takes to switch.

I first thought that i got the solution, but that was not true because when i tried to replicaed using an Arduino, mosfet and my bench powersupply, it just was stuck in a bootloop.

Also when i tried to put 5V directly from my PSU to the sensor, still bootloop and then it got very strange.. When i use a normal phone adapter using a normal MicroUSB cable, it just worked (ofcourse no battery data…) but no bootloop! I even tried to get the voltage from my PSU as close as the voltage form my phone adapter, still bootloop. I also checked if my phone adapter was maybe creating a signal on the datalines that might trigger the sensor to go in some sort of debug/desktop mode.

But i didn’t noticed any voltage on the dataline.

So that is why i am really stuck on this one, i really really hope someone is able to help me or at least put me in the right direction. Anyway, thank you very much!!

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