Votage usage

Posted by Damo on August 17, 2013 at 2:53pm

hello,

i want to figure out if my 3dr voltage monitor is working correctly

I complete a test with 2 of the EXACT same 5000 mah 3s lipo batteries.

I have a cheap low voltage alarm on the battery also. I launched to about 4 metres high and engaged loiter until the cheap low voltage alarm screamed.  I executed this test for both batteries.

So my question is :

Does the voltage as logged via the mission planner look correct ?

The reason i ask is so i can understand if i can enable the low voltage RTL safety feature.

thanks

Damo

3691050364?profile=original

3691050414?profile=original

BatteryA-2013-08-17 21-59-41.tlog

BatteryB-2013-08-17 22-22-51.tlog

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Replies

  • dr0n3droid August 18, 2013 at 8:34pm
    I've been using the PM for a few weeks now. Have had many battery failsafe triggered. My lipos are quite old. Voltage drops rapidly at high current, even above 60% charge.
    I have noticed that PM reads a lower voltage than my multimeter.
    Preflight
    MM_12.55v
    PM_12.20V
    Post flight
    MM_11.3
    Pm_10.97

    So I adjusted the failsafe voltage accordingly. Seems much better now.
    What interests me is copter behavior when land/RTL failsafe is triggered. Hovering(important?) at 5m, when failsafe is triggered causes me no issues. Just a calm RTL or land. However if at 20m, 80% throttle, a low_volt failsafe is triggered during a hard 180° turn, it's likely going down. I guess it's no different than if I were to change modes myself at high speed.
    Just my own observations, speculation, and crashing, not sure what happened to Chris, nor am I suggesting you risk your bird. However, if Land/RTL are working properly for you, and you know your flight time(11mins), you could test it out.
    Be prepared for possible failsafe at any time during the first few flights. Just fly accordingly. Track MP battery%out vs mah charge in.
    To test if the battery failsafe is working, you could raise low_volt.
    @chris
    What was the copter doing when failsafe kicked in? How high, how fast, etc. Crashes are ok, as long as we learn from them. Hit the ground three times today. (Re)learned a few things.
    1. Need bigger batteries.
    2. Need more power. Or lower WPNAV_SPEED_DN
    3. Sometimes 5m is only 1m.
  • Chris August 17, 2013 at 10:49pm
    Damo I was recommended to not use the PM's failsave for the time being while using FM 3.01. It caused my Hexa to go in a sudden Land mode while in Stabilized, and crashed unfotunately.
  • Ben Cairns August 17, 2013 at 3:42pm

    It looks about right, very progressive and linear usage. 

    how long is the flight?

This reply was deleted.