Thursday, September 10, 2015

APM Power-Module install

My first APM Power-Module install . I used this PM with yellow XT-60. This one has a 5.3v BEC, but I'm not using it yet (still using BEC on Nova's PDB).

I carefully removed the proper pins from 6-pin PicoBlade and inserted into 3-pinner.

Black Sharpie marks the Ground pin. The other two are Voltage and Current Measurement.

Here are some supporting pics from FatQuad and DKEmxr on RCGroups Forums about PowerModule. This is a APM252_v5.0 FC (with ADC port).

From the pic below, using Pins 3, 4, and 5. Not currently using BEC/+5_VCC portion.

I used the main-power XT-60 connectors at first for initial hook-up and testing, but I eventually found them too cumbersome, so I spliced it in. You could also just re-wire and re-solder with proper gauge wires.

Settings & Calibration:

ArduCopter Power-Module Setup page

My Battery Monitor (Power Module) settings in MissionPlanner 1.3.37.

Using Turnigy 11.1v 2700mah 3s 20-30c LiPo.

Initial Setup/ Battery Monitor
Monitor 4:Battery & Current                  Battery Capacity: 2700
Sensor 0:Other
APM Ver 2:APM2.5+ 3DR Power Module
1. Measured Battery Voltage: 11.6v
3. Voltage Divider: 10.82
6 Amperes Per Volt: 19.1

For this Nova 2.52_v5.0 Flight Controller (ADC-Port Sensing pins) Parameters should be


  1. I can buy a power module without bec and do the same modification cables, and keep using pdb cx 20, I'm right

  2. This comment has been removed by the author.

  3. Thanks for all your work! One thing that's annoyed me is the need to occasionally unplug the power and plug it back in after a hard landing or tip-over. Have you considered placing a power switch on the outside of the body? I was looking at one at radio shack for about $2 that's rated at 3 amps at 125v AC. It's rather small. When I look at the gauge of the battery wires compared to the switch I'm not so confident about putting it in. Any thoughts on this? I have a smaller quad and it has a switch and like it much better having it.

    1. I know this is old, but if you put that switch on the 5V line going either from the receiver to the APM or from the PDB to the receiver, it should work for resetting the drone. The ESCs would still be powered, but switching them would require either a much larger switch or a high current relay.

    2. Corey, thanks for the post. So, would you do it, or would you rather not have an extra point of failure (extra chance flight-controller might lose power).

  4. Hello Tesla,
    thank you for that much information on the blog. I ordered a QN with PCB-1: APM_V252_V2.0 and PCB-2: CON_V2.0 like your first QN. Can I connect a powermodule with volt&current measurement to the PCB-2? Saw people soldering it directly to the CPU?

    1. This easy way only works for APM252_v5.0 FC. For v2.0 PCB, you will have to solder directly to CPU pins (since it lacks ADC port ... that provides pins).

  5. Great tutorial. I have one question. Do I need something to do with jumpers or other power lines and so. Or just connect Power module to battery cable and connect this 3 wires with 3pin plastic connector to APM.

    1. Thanks. On the APM252_v5.0 ... this is the complete required hardware changes.

    2. I have APM2.52_v2.0 Is procedure same?

    3. No ADC port on Cheerson APM252_v2.0 FC

  6. I do everythink like u say. If i use "APM2.5+ with 3DR" I have strane volt values. After that i use "APM2.5 non 3DR" and then also strange but when do volt calibration everythig is fire. But problem is with amper value. A in mission planner is always the same. I try to do amper meter calibration with props on and calibrate amper meter and nothing happend when i turn down trottle. Mesured value is cca 10A and put down in Mission planner Battery monitor page and when pull down throttle amper sill set to 10A (in Mission Planner. Dont go down. Thx for help.

  7. Hi I have instalation/calibration power module problem. When I calibrate volt on one battery value isn't correct when i plug another one battery.
    My video:
    Also I try to calibrate current with props and when measure 10A on ampermeter and set it in mission planner when i turn the thottle down amper stay at the 10A?
    My video amper calibration:
    I connect my power module ( to the CX-20 (apm 2.52, costume firmware 3.2.1) like i see in this tutorial.
    Please help me. Can be a problem in firmware?

    1. Mine is working but I don't have all steps and settings documented. If I ever do, I will post them to the bottom of the above post.
      I doubt firmware, but maybe settings or calibration. IIRC, you can set "sensing pin numbers" in MissionPlanner.

    2. Hi. I have the same problem as Mateo Gašparović.
      Have you got a solutions for this?

    3. What i messure from the PM is pin: #1:+5,2 #2:+5,2 #3:0(current) #4:+5,8 #5:- #6:- this is with a that has 12,2volt

  8. Hi Tesla, Cheers for the super informative resources. I have a 4in1 esc with built in APM style current sensor with the exact pinout sensors as above.

    However I intend to use this current sensor for my EagleTree μVector FC which has a single input for any analog current sensor, max 3.3V (can calibrate).

    In your 3rd picture, for pin(3) VCurrent, does it fit the criteria of a (max) 3.3V analog signal proportional (or dependent) on analog voltage sensed?

    Also, for pins (1) & (2) is it 5V output (as in 5V supply) or 5V input?

    Any help would be massively appreciated!

    1. This is a Chinese clone of the 3DR APM Power Module. It is fairly commonly used in APM and PixHawk circles. Yes Pin#4 is a measurement of the current draw on the attached main LiPo battery input, represented in an analog voltage (yes, likely between 0-3.3volts but you can measure it with an ohm-meter first). Pins #1-2 are the +5v-DC OUTPUT. It's normally used as the craft's BEC circuit to supply 5v to the flight controller and other sensors. It's on 2 wires because the wires are small gauge. In this use-case, I don't use this BEC because the Nova has it's own BEC on it's Power Distribution Board. I know it works with 3S LiPos. I'm pretty sure it also works for 4s LiPos also, but that is likely it's cell-count limit. Does that help?


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