Some background: I've been having trouble with my H4-3D freaking out several minutes into flight. At about 6 minutes the gimbal goes crazy. not like it's resetting but it points skyward and rocks back and forth. The last flight I noticed that my IOSDMk2 began dropping it's signal and turning back on at the same time the gimbal freaked out. This got me thinking that it might be a power supply problem and NOT a gimbal problem.

Here's my idea... I'm thinking about re-wiring things so that the video subsystem (transmitter, gimbal, and IOSD) are running on their OWN battery, namely an S3 battery from my phantom. The motors will still be powered with an S4 battery.

Here's my questions:

Will separating the video from the propulsion system leave more power for flight? I know it will; but will it free up enough power to offset the cost of carrying the S3 battery? I have a heavy bird as it is and don't really want to carry more weight but if it fixes the gimabl freak out it might be worth it.

Where does the IOSD get it's voltage information from? The power running through it? Or from the PMU?

Thanks
Doug

So I decided to try powering the video system separately.

I now have the Video transmitter, IOSD mk2 and gimbal all on their own battery.

I plugged an S3 (phantom) battery into that setup and to my surprise the F550's LEDs came on. The power does NOT touch the main propulsion PMU or Controller. The only line these components share is the CAN-Bus data connection.

Big question... Will I damage my machine by supplying power to the can-bus from two ends?

This can be a issue depending on the BEC  and wiring you use.  The DJI system is designed to power most DJI accessories through the standard connections.  This power comes from the PMU unit.   The GCU on the gimbal powers the gimbal.  Since this is connected direct to the battery power it should not cause problems.  The other issue you can run into is not having a common ground and this could impede correct transmission of signals from the Naza to the gimbal.  Back feeding power to the Naza could be a problem if the two power sources fight each other.  the  devil as always is in the details.  how it is wired and what components can make a big difference.  I would opt for a single battery  for simplicity.  My guess would be you are not benefiting in flight time.

joe@heliflightc Posted at 2015-4-30 21:44
This can be a issue depending on the BEC  and wiring you use.  The DJI system is designed to power m ...

Thanks. You articulated most of the questions that ran through my head before I connected the second battery. I don't think I'll be trying it anytime soon.

Also I am beginning to think that the gimbal freak out might not be a power issue but a heat issue. I ran 4 batteries yesterday. Bat 1 No freak out. Bat 2 end of battery. Bat 3 mid flight. Bat 4 mid flight.

I wonder if the gimbal just needs more rest time between flights.

Doug