This question is both for a pixhawk and an APM 2.6 (I have both).
Short question is that I have 2 12V lipos. I’d like the first one to run the motor and the second one to run the flight computer, servos, camera, and OSD.
This way if the throttle battery runs out of juice, the 2nd battery can still control the flight computer which in turn can talk to servos that are also powered by the 2nd battery (and of course the OSD and video are still running too)
I know that the APM 2.6 (and I’m guessing pixhawk too) doens’t provide enough current on the 5V outputs to run servos.
Currently I have a 12V lipo connected to an ESC that acts as BEC and feeds power to the pixhawk/APM2.6 via the throttle input.
At the same time, pixhawk/APM2.6 also gets power from the power module.
I’m not sure how many amps the power module can provide to the arduino, but looking at the thin wire sending power to the arduino, I’ll guess very little
Now, I have a 2nd 12V lipo that powers a camera connected to a miminOSD.
The board has a 12V to 5V voltage regulator too, but I’m also going to guess you can’t source enough current from it to power servos either.
Also, I’ve read that I should consider powering the miniOSD from the 5V side and not the 12V side because the 5V voltage regulator is noisy. hoogvlieger.wordpress.com/2013/1 … sd-5v-mod/
Questions:
0) Is my APM 2.6 currently getting 5V current from my ESC and passing that on to the 5V servo output, therefore providing enough amps to control the servos?
what is my best way to power at least the pixhawk or APM2.6 from the 2nd battery?
doing #1 would be good, but if the servos won’t move, I guess it’s not that useful
if I have a 2 battery setup, is there a good way to get voltage level for both batteries into the pixhawk and APM2.6? Better, can that be passed to the minimOSD somehow to show 2 voltages?
Back to my main problem, does it mean that I effectively have to buy a BEC, in other words a 3rd device converting 12V to 5V, to make things work like I’d like?
Isn’t there an APM power control board that can act as an ESC which has enough current to power servos?
Or any other way to do what I’m trying to?
[quote=“marcmerlin”]0) Is my APM 2.6 currently getting 5V current from my ESC and passing that on to the 5V servo output, therefore providing enough amps to control the servos?[/quote]No, Inputs and outputs positive circuits are separated, the 5V from your ESC can be used to power for example servos. As far as I know there is no redundant power option for the APM. Here you can find more information: copter.ardupilot.com/wiki/common … 2526_Board
[quote=“marcmerlin”]1) what is my best way to power at least the pixhawk or APM2.6 from the 2nd battery?[/quote]For the Pixhawk you can connect a BEC to the output rail, here more info: copter.ardupilot.com/wiki/common … er_Pixhawk
[quote=“marcmerlin”]2) doing #1 would be good, but if the servos won’t move, I guess it’s not that useful[/quote]Even when you still have power to the Pixhawk, if the battery which is connected to the ESCs (and motors) fails you won’t able to control the vehicle.
[quote=“marcmerlin”]3) if I have a 2 battery setup, is there a good way to get voltage level for both batteries into the pixhawk and APM2.6? Better, can that be passed to the minimOSD somehow to show 2 voltages?[/quote]You can only connect one battery monitor to the Pixhawk and APM, and the minimOSD doesn’t have a battery monitor by itself, it will take the data from the Pixhawk or APM.
[quote=“RogelioN”]No, Inputs and outputs positive circuits are separated, the 5V from your ESC can be used to power for example servos. As far as I know there is no redundant power option for the APM. Here you can find more information: copter.ardupilot.com/wiki/common … 2526_Board[/quote]
Thanks. I did read that page, and looking at it again, it seems that I can provide power to the APM both from the output/servo side and via the power module.
At this point, it sounds like what I need is to get a separate BEC to provide 5V to just the servos and the APM. That way if the first battery dies, I lose the motor, but since I have a plane, I can glide the plane to landing with video and GPS coordinates all the way down (or almost) to find the landing/crash site.
The one thing I’m not clear about is the JP1 swich. As far as I can tell, I can leave JP1 and power the APM from both sides so that if the voltage regulator on the power board dies or its cable gets disconnected, the APM still gets backup power from the servo/output side and continues to work. The protection diode should ensure that the power module isn’t trying to power servos.
So I’m really not sure why one would want to remove that JP1 switch.
Thanks, so you’re confirming that dual power on the pixhawk works. Now interestingly I’m doing the exact same thing on the APM 2.6 too. With the JP1 switch on, it also has dual power and works just like described above, does it not?
You’re correct, it looks like I need to buy a BEC to power the pixhawk/APM 2.6 from my 2nd battery (which will also power video/OSD) and use the first battery only for powering the motor. That way, if the motor battery runs too low, I can still power everything else and control the descent and landing assuming I have video reception.
Thanks also for confirming that by default the APM and pixhawk can only monitor one voltage. Obviously I can monitor a second one if I use an analog input and write my own code, but that would be kind of involved and as you mention the OSD wouldn’t be setup to accept that data.
For now, I’ll just have to assume that my 2nd battery will outlast the one that runs the motor and I shouldn’t need to monitor it. I’ve seen other OSDs that seem to monitor 2 batteries, maybe I can look at that too.
