Using a power module without BEC daughterboard?

Hello guys,

I bought a Power module to have information about power consumption displayed on my OSD, 

Unfortunately I bought one without the BEC daughter board so instead of supplying the 5v out for my APM it gives me the LIPO out voltage. I haven't tried to plug the VCC and the GND to the APM, I don't want to burn it. 

The power port is made of 6 pins:

Inside of APM

-- GND

-- GND

-- V ?

-- I ?

-- VCC

-- VCC

Edge of the APMboard.

I guess the V and I pins are for the "information" and the GND and VCC to power the APM board, no?

So I've tried to plug only the two middle pins I and V but it won't work, Have someone succeed to use this kind of power module, I can power the APM with a separate BEC via the power port (on VCC and GND )maybe?

My power module:


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  • Dear All

    Can I use for big copter?


  • I thought Vcc and GND were the other way round. Are you sure about your schematic?

  • You need to use the ground wire too. Solder wires to the solder pads in you photo, just don't use the +5v pad. Attach the GND V and I pads to the Analog pins on the side of the APM. You can choose which pins to use in the parameters. The V and I will hook to the designate inside (signal) pins, and the GND will be any outside pin, they are all the same. Use a good quality 5v UBEC on the input pins or Analog Pins to supply APM power.
    Many people actually prefer this technique over the Power Module.
    • Can you use the multipin DF13 connector to the APM and not go the route of the Analogue pins? There is after all the supplied wiring harness that comes with these "Ebay" type, what are they calling it..." APM2.5 P & W Module" I have already decided to go with the 3A/5V Low Noise UBEC thru the INPUT pins. 

      Thanks for any advice here, I have been chasing my tail on this one as I get the physical layout and routing of wires /components on the frame. It is a little hazy at best. And then there is the difference in the Wiki's of both MinimOSD or MinimOSD Extra. As to how you get it working with the GCS (Mission Planner)

      I understand that for any of this to work they must share a common ground naturally as I power the UBEC from the same battery that I will be using the Module sending "V" and "I" data. 

      Care to shed some light for the first timer who is up to their armpits in methods and procedure?  :-)



      • CGL, you may want to post this question out of this thread along with a sketch of your wiring.

        I cannot stress the importance of at least a basic sketch of the wiring -- it does not have to be a work of art, just accurate information on what you have connected (even is it is connected inaccurately).

        Paint (or other basic pixel drawing programs) have been around forever and are easy to use. With a posted sketch we can provide a 'move this wire to here and disconnect that wire' kind of feedback.


        • Thanks I have already sorted it out, and what thread would you suggest as you whisk me away?

          You are talking about the the very item I am referring to. The Ebay type "APM 2.5 V-I module" that people are mistakenly purchasing. Better to make the purchase of the real item, say from Hobby King. Or an Attopilot from 3DR !

          That is precisely what I have done.

          • So basically the no BEC power module are a waste at just being used for battery monitoring?
            • Thanks for your inquiry, I just hope that this is the correct thread to continue here on this topic. Don't want to ruffle anyones feathers. I would however like to be informed immediately the correct thread to post this on if I am in error.  

              So to respond to your reply Mark, I was on a fairly strict budget when I started to acquire various elements for the construction of my first quad.. It was the Hobby King X650F that I had purchased for the first of such projects. I made a list of essential items and then shopped it around. Naturally in trying to stick to this pitiful budget I tried  to save money wherever possible and fell into the trap of assuming  if the item was labelled "APM 2.5 Power Module V + I" must be the real deal. Well an experienced eye would have  caught the missing daughter board that produces the regulated 5.35V. Of course upon receiving it I noticed that there was missing elements on the parent board. and wondered what it meant. Oblivious to the nature of this matter I went ahead and soldered up the battery leads and then began the testing to see what data it was sending and voltage was outputting. There was no 5.35V anywhere. It was then I put on the binders and started to question just what it was that I had purchased two of for such a "good" deal. 

              There is no way I am going to use either of them until I can find out if they are only missing the BEC output totalling 5.35V allowing for the Fuse/Diode that consumes ~0.30V to do its job and then the remaining 5.0 V is upto the F.C. .

              Rack it up to experience. I will wait till the correct item arrives in the post and after that I will compare the outputs and see if I could use it as a simple Voltage and Current sensor connected to the Analog inputs where the Attopilot would be connected. I believe it is A2, A3 and Gnd. 

              In the interim I have read much of what Jabram's Blog at RCG has to say on the matter. and have decided to use the tried and true method of powering the APM2.5.2 thru the Input pins with the J1 removed. This 5V/3A UBEC is available from RCTimer and HK and works well and has a filtered low noise output as well as a ferrite choke as well. 


              • My power module is working without the BEC daughter board, just do not plug the Vcc on you APM cause it's feeding 12v instead of 5... I use a separate 5v BEC. This board is used to monitor the V+I of you lipo otherwise you can power the APM via you ESC and a jumper.


                • Thank you, that what I was hoping. I have been using my APM2.5 with a UBEC for quite a while but now need to output battery info so thought the no BEC version would be ideal. Are you still plugging the lead into the apm power port or have split the wires and are using the analogue inputs? Do I just need to cut the first pin(red) to kill the 12V.
                  Again many thanks
This reply was deleted.


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