Questions about the APM2


i have a few questions about my new APM2, going on to my Y6-Copter so i thought, I'd bundle them here:

1) How come, if i have the Power-Jumper deconnected, and the BEC going into the APMs Input rail, I don't get my reciever to power up, even though it is connected with a Female-Female Cable going to the Input Rail?

2) In the APM2 manual ( under point 2) ) when talking about the flightmodes, it says mode 6 always has to stay manual, as a Hardware-failsafe-backup. Does that still apply to the newest APM2? Because if i go into the flightmodes menu, i can't even find "Manual" to choose from the list, and it was by default on "stabilize" in mode 6

I'd be happy about any answers!



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  • Hi all,

    Iam very new to this and i would like to say what a great piece of kit the APM2 is.

    I have successfully flown an Easyglider on many missions straight out of the box (i did do the twin-ailerons mod though).


    Iam now putting the APM2 in my Cularis.

    I was worried about the Cularis ESC/SBEC putting out 5.5v to the APM2 so i searched for advice and found this thread - and iam very glad i did.

    My plan was also to run a separate SBEC of 5v from the same battery powering the servos.


    Anyway, my point is that I think it should be made clear in the instructions as a 'Warning' not to use the same battery, to avoid anyone putting their APM2/Aircraft at risk.

    Or maybe iam just stupid.


    My solution in the end was to purchase an ESC/SBEC that puts out 5v.





  • Yes exactly Vernon... Then it must be a misunderstanding, i must have missed the fact that you were talking about the SAME battery... Of course i assumed when i talked about independent power source that the BEC must have been powered by a separate battery ! I'm wondering what would be the point of powering both ESC and BEC with the same battery anyway...

    Since you seem to be highly qualified in electronics, how would you recommend me to power the input rail ? Should i connect the 5v BEC straight into an unused channel of the APM2 or should i connect it using a Y cable to one channel of the Rx (if i remember well it's the recommended method in the manual of my Graupner radio) ? I've seen some BEC with two outputs would it be of any use ?

    (i'm using a 3S 5000mAh lipo with the ESC and a 2S 1000mAh lipo with the BEC)


  • Thanks Barry,
    yeah, i noticed my fault of thought with the manual modus shortly after posting it, of course that was for planes only!

    However, i don't understand, why i shouldn't power from the input rail, as this is a given option (first paragraph here: )
    I'd like that, because i have disconnected the Internal BEC of the ESCs, and have an external BEC instead.

    I didn't have the USB plugged in, i remember the whole problems with the APM1 having brown outs, when only powered by USB.
    When i connect up the USB cable, i make sure, i have the normal powersource connected before plugging in the usb!



  • You need to be following these specific instructions for Arducopter since that's what your are building.

    The arducopter APM2 specific info

    Again, go through the APM setup first, then follow each direction from the main page and you'll be flying in no time.

    Trust me, I've built both a quad and the new hex and both flew perfect the first time when I followed the directions step by step. All a Y is my Hex with motors on the bottoms of the arms. I highly recommend you use the power distro board from DIY drones. This will make your life a lot easier and prevent some fatal wiring mistakes regarding ground and 5v power to the APM. Also, we've seen some home built power distro boards and it gets downright dangerous if they cause a short with LiPo batteries as they tend to catch fire. My stock hexa with the 850kv motors would max amperage 18A per motor X 6 =108A!!! Obviously normal flight hopefully won't hit that high but my first flight was with an older 3 cell 3P pack rated at 6600mah and a conservative 8C rate which got considerably warm during the first 12 minute flight. One guy here in the forum was usign stripboard for power distro and the problem is that it's only copper glued to cheap pcb board, single sided and not plated through with the wires all on top(copper side). The problem is, tension on the wires or heat could cause the copper to peel off the board and then short the battery since nothing prevents them otherwise.


  • First off, don't put power up the radio input rail! there are diodes on board to stop this. The main reason is a clean path of power from the outputs going to the ESC are meant to be the power input to the system. My best advise to give you is follow the wiring diagrams exactly and do not skip any steps in the instructions. 95% or more of the problem here in the forums are by people re-engineering the wiring and not understanding that there are reasons for the way the board is designed and the system as a whole.

    That said one other reason is that when you power via USB, the limit is 500ma and even that may trip up a USB port so diodes are in place such that the outputs are not powered when USB is plugged in.

    Next, you will never, ever put any type of multirotor (hex, quad, y, octo) in manual mode. You need stabilize just to be able to keep the thing in the air. All other modes are advanced versions of stabilize to add more features (loiter=stabilize+ stay in one place based on GPS), (Altitude hold=stabilize+stay at altitute) , and so on...

    Manual mode only applies to planes, thus when you load multicopter firmware, the option is removed.


    Again, the best advise I can give you is do not stray from the instructions on any step or wiring. You need to use a power distro system that exactly follows the wiring diagrams so that proper ground path and 5 volt power is distributed per the diagrams. Further, the ESCs are connected in a very specific way to prevent gournd and power loops due to the high currents involved which could damage components if stray currents pass through the pins of the APM.


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