I had a bad crash with my hexa and to my surprise the APM power unit kind of exploded.

So I wonder: Is it a risk to use this device?

Views: 2591

Reply to This

Replies to This Discussion

Picture ?
Maybe not a risk, but it's really weak and easy to overload by serves or OSD.


The APM Power Module is not meant to power servos, but does a pretty good job of powering the APM, R/C receiver, GPS, compass, and 3DR telemetry radio.

I used a Power Module on my Slash Rover during the Sparkfun 2013 AVC and had no trouble whatsoever with the module even though my rover took a direct hit from a wayward VW bug at the start of the Peloton Class second heat.

The PM powered my rover's AMP2.5, uBlox LEA-6 GPS, outboard Honeywell HMC5883L compass, and a 3DR 915MHz telemetry radio.

During pre AVC testing, my rover suffered a couple of rollovers and the PM never failed to function after each crash. I have quite a few testing and competition hours on my rover and its PM and both continue to function just fine.


TCIII ArduRover2 Developer

The servos are powered bei UBEC

On my hex this just had to power APM + GPS.

Telemetry + OSD + Servos + LEDs were all powered by UBEC.


Looks like your PM was in an exposed area of your aircraft where a crash could cause physical damage to the part. Or there was a short circuit on the PM's output.

I have rollover protection for all of the hardware mounted on my rover just to preclude such damage.


TCIII ArduRover2 Developer

Now that you said that I think you could be right. The clear plastic isolation is flipped over like it was cut out.

I agree, that does not look like an electrical fault, but mechanical. If it was electrical power failure you  almost always see heat damage.

It's not weak, it can output 2.25A, the issue is that the original APM2.5 has a 500mA limiting fuse from the PM to the Inputs rails (to protect the APM) and this means you cannot connect too many things to the input rail as you easily get near to that limit. The newer APM2.5/2.6 are fitted with a 1.1A  fuse, so you can power a few more things from the Inputs Rail.

On the older boards, if you take the power before the fuse, you can leverage more of it's capability.

I have read this sensor can handle 90A.

But when I calculate: 20A ESC *6 = 120A.

Will it handle that?

I agree that cause seems to be other than electric, but looking the PM specs( outputs 5.3V and 2.25A max,)  I would like to know if someone has measured or estimated the total drawn current by APM 2x set + OSD + Telemetry + Airspeed kit ? How far the 2,5A is the PM working in average?

200 - 250mA on average. With a standard RC Receiver.

But there's a 500mA fuse that limits the current to input rails (as part of over voltage protection), if you take power from the 5V pad on the back of the PM you can supply more of that 2.25A, or connect JP1. But you loose separation of power, so the servos can generate noise on the line to the APM.

This is why the recommended config is to only power APM from the PM plus a few accessories, as this means that most people follow the recommendations and don't need to be an electronics engineer to go fly.

If you would like to come up with novel powering options you can use the eagle files and the documentation, it's all about trade-offs.

See copter.ardupilot.com for more info on the power layout
20A is the max rating of the ESC. The current consumed varies depending on the throttle, size of props, motors kV and load. Measure the current consumed and you are most likely not even half that current per motor at full throttle. That's only 60A

Due to hardware and functionality design, there are only 2 well known ways to power APM 2.x. Now  with 1.1A fuse in new release more room to power additional stuff but relaying in PM module reliability. I rather to use PM only as current sensor and to use external high current capacity bec. AMP outputs feed from ESC.  

Reply to Discussion


© 2017   Created by Chris Anderson.   Powered by

Badges  |  Report an Issue  |  Terms of Service