I have also repeatedly experienced strange behavior after swapping out the battery for a fresh one. It startled the **** out of me the first time it happened. I have been fortunate enough to recognize this behavior at lift off in my case. This has been repeated almost every time I’ve flown.
First flight is normal, with no issues or warnings. Sat counts are green for H+ and I have between 8-11 Sats for the ST16s. All batteries being used have been recently charged using a DY5 charger. The issue starts as soon as I swap in the second battery. Upon power up of the H+ with this second battery, all Sats are the same and battery indicator for the H+ shows 100%. The only thing different is I get a warning to check for magnetic interferences.
It should be noted that upon take off each time, I will lift off and hover at 4’-5’ for a short time and check to make sure the H+ is responding to my inputs before heading off in to the wild. After power down of the first flight, and replacement of the H+ battery, the H+ is restarted. The ST16s is not powercycled. As the H+ powers up and reconnects to the ST16s, this is when I get the “Check for magnetic interference”. At no time during the first flight did this warming pop up.
Upon lift off, the H+ does not hover and begins to slowly climb in altitude. The down stick is very sluggish and almost unresponsive in its ability to bring the craft downward, however it does come down, just really, really slow. I’ve also started hand catching the H+ and using the red stop button to stop the motors. In my last 2 flight sessions, in both cases with this swapped second battery and hand catching, using the red stop button has no effect. The motors continue to run for 10-20 seconds (I may be wrong on the length of time, but it ‘s not the usual 2-3 seconds it takes for the craft to power down). It’s as if the commands from the ST16s are not being given to the H+ to power down. This I don’t have a workaround for, and I don’t think it’s a good idea to try and use either the power button or remove the battery with the props spinning, so I just hang on.
If I powercycle the ST16s when I swap in the second battery, the H+ fly’s normal. I have not experienced any mid flight power losses to date and where I fly, I’m pretty certain I wouldn’t find the drone if it went down. As indicated, the only thing I’m seeing in this process is the addition of the check for magnetic interference warning.
I am running the latest firmware and did not have any issues with my gimbal or camera buzzing (to the best of my knowledge). I have also not looked through any of the flight logs as I’m just now seeing a pattern, or what looks to be a pattern in my case.