Battery voltage oscillations

Hey everyone,

during the last 5 flights with my Pixhawk powered Skywalker 1900 I started to get some weird periodical voltage oscillations. Those oscillations occur rather regularly throughout the flight and then stop again.

Normally my amplitude of highly frequent voltage change is in the range of 0.2 volts. Then, all of a sudden (and without applying more throttle) the amplitude changes to > 1 volt. This lasts for about 30 seconds, then goes back to the normal .2 volts amplitude. Then its fine again for a couple of minutes, until it starts over again. When the unnormal oscillations begin, this also affects servo rail voltage and board voltage, so I am a little worried of a brownout.

Has anybody an idea what the problem could be? I would be happy for some advice. My APM.Plane version is 3.3.

The log file can be downloaded here: … 5.log.html


I have done some testing in the meantime, such as to remove my capacitor bank and to use different batteries but the problem still persists.

Furthermore, I have noticed a strange regularity in the occurrence of the oscillations. They seem to recur every ~8 minutes. I have attached two graphs of two different flights, showing volts and current.

Has anybody maybe got an idea where else I could be trying to solve this issue?
Thanks, Matthias