Power Profiler Kit 2 measures exponentially decreasing current at constant current

RE: Power Profiler Kit 2 measures exponentially decreasing current at constant current

lukas76352 — Thu, 26 Oct 2023 13:28:56 GMT

Took me a bit longer to get back to this, but your suggested wiring works mahboud , thank you!

RE: Power Profiler Kit 2 measures exponentially decreasing current at constant current

lukas76352 — Thu, 28 Sep 2023 15:17:30 GMT

Hi,

Thank you both for your replies.

@mahboud: This is the wiring I initially tried, however, I got the same result. I then changed to the wiring I described above, because it seemed closer to what is written in the PPK 2 manual.

Regarding the 800mA: The battery cell is empty, hence I am expecting a large current and to not damage the PPK, I limited the current to 800mA, which is what the PSU is outputting and also what I measured with an additional multimeter.

@hmolesworth
I don’t quite understand how the set up could have damaged the PPK. Could there have been such a large potential difference between the USB GND and the PSU GND that a large current balanced the two potentials?
Anyways, I hope it didn’t damage the PPK.

In any case, I will check if the PPK still works as expected in other situations and I am also going to retry the wiring that you suggested.

Thank you for your help and I’ll get back to you sometime next week.

RE: Power Profiler Kit 2 measures exponentially decreasing current at constant current

mahboud — Sun, 24 Sep 2023 23:31:45 GMT

Lukas is trying to measure the current that the battery is drawing. There is no nRF52.

The wiring I'd use is
PSU + to Vin
PSU - to GND
Battery - to GND
Battery + to Vout

That's very similar to what Lukas has except he uses the PSU GND instead of the PSU -.

Lukas, can you try changing the connection to PSU GND to be to the PSU - instead?

Also, why do you think you should have 800mA of current? That's the maximum that the PSU allows, but a somewhat charged battery could only take a trickle of a current or a fraction of the 800mA.

RE: Power Profiler Kit 2 measures exponentially decreasing current at constant current

hmolesworth — Thu, 14 Sep 2023 15:38:43 GMT

Incorrect connections, remove and connect as follows:

PSU GND do not connect or optionally connect to PSU '-'

PSU '-' connect to both PPK-II GND and nRF52 under test GND

PSU '+' connect to PPK-II VIN

PPK-II VOUT connect to nRF52 under test VCC

Note GND on the Bench Power Supply (PSU) is not necessarily the same as GND anywhere else. If using a grounded MacBook Pro then USB GND may be the same as PSU GND, but when the MacBook Pro is not connected to a power supply its GND is floating with respect to PSU GND. For now just ignore GND on the PSU.

Note also the PPK-II may have been damaged by the connections used in the original post; fingers crossed that it's not ..