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3DR Power Module Maximum Amp Behaviour

Posted by Ben H on February 21, 2013 at 6:06am

Howdy, got some questions about the 3DR Power Module on APM2.5 I snagged from diydrones that I haven't been able to find answers to, I'll keep it in point form to make it easier to convey them and I'm hoping someone could chime in to clear them up for me.

1)  I understand the maximum current measurement on the unit is 90amps, what kind of behavior does the module exhibit once that draw is surpassed temporarily during a spike?  Does the reading just top out and everything functions fine barring wiring/solder failure?

2)  What would be the maximum current the board itself can sustain for short bursts without blowing components?

3)  What's the maximum constant current draw that the unit is rated for?

This is all on a 4S system.  Thanks!

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Replies

  • Developer
    Bill Bonney February 22, 2013 at 10:15pm
    The limit is in respect to the voltage output to the analogue to digital converters. The 90A is scaled to the range of 0 to 5V on the APM, if you draw 100A that's ~5.5V on the ADC. No problems, but the higher the ADC goes above Vcc (Voltage supply to the chip)on the APM the more likely it might blow up. The current measurement is unrelated to the current drawn by the APM.

    The APM with RC and telemetry draws about 250mA. It has a solid state fuse that "blows" at 1000mA .ie rated for 500mA nominal use.

    The APM PM is rated for 18V so a 4S battery is ok 4*4.2V per cell.
    • Fun Wey > Bill Bonney March 30, 2014 at 6:36pm

      Hi;

      I am using the Pixhawk for a heacy-duty Y6, with max current drawn at up to 300A.  Obviously I need to by-pass the current-sensing in the power module and connect more battery in parallel.  I just need the pixhawk to monitor the voltage of the array of battery and beeps me when the voltage is low (say < 3.4V per cell).  How to set it in the APM2.0?

  • Ben H February 22, 2013 at 3:21pm

    Well, just ran a few batteries through it @ a steady 75 amp controlled load.  Having trouble exceeding that in a controlled environment but I'm sure it will hit it when it's flying around.  Still would like some insight on this from anyone that has experience with it.

  • Luke Olson February 22, 2013 at 3:29am

    To put things into perspective the connectors on the power module are rated for 60 amps.

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