Help needed with DJI WKM flight times

[david.scarbrow]

While I am still awaiting for the design of the landing gear for my quad to be completed I decided to make a temp one up out of locally purchased 10mm ali tube. Following a quick back-of-fag-packet design and some (dare I say) more than skillful work on my part with a pipe bender I manaqed to put something together that seems extremely strong, reasonably lightweight and fit for purpose. The airframe is a WKM driven aluminium Bagheera 600 with AXI 2814/22 motors, APC 13/6.5 props currently powered with 1 x 3s 5000mAh 60/80 battery. It will have a second identical battery to be used in paralel once I have built the wiring harness...so that I can understand better any issues I am 'flying' the quad with the weight of both batteries on board. According to ecalc I should get approximately 6 minutes of flight time for that weight with 1 battery and approximatley double that with 2P....I seem to get around 3 minutes max hovering at 2 metres before the continouos flashing yellow led leading to another minute of flight time before the continouos flashing red ending up in a very nice soft landing. My understanding at this time is that the AXIs will create enough thrust to drive 4 kilo (although I do not now for how long)...I'm obviously doing something wrong and I can't figure it out...anyone got any ideas ?

Please view/reply post on DJI Innovations Forum...this post was incorrectly placed on this forum.

 

[Droider]

What is your battery warning on the WMK set to?

Have you calibrated the battery monitor?

Dave

 

[david.scarbrow]

Dave, I'm at work at this time...I will check when I get home tonight...but yes I did do the calibration and I seem to remember the 1st level battery warning set at 11.2v and the second level at 11.0v...do you think this could be my problem then ?

 

[quadcopters]

Dave , Geoff here .. Yes way too low them settings , You need to be in the region of 10.5 -10.6 first warning and then I usually set mine 10.2 for final warning auto descend.
Also as Droider mentioned calibrate your voltage monitor, to do this just get accurate reading with voltmeter or lipo alarm and then enter it into the Wookong Program and save..

Also might be worth switching to 4s lipos ,

Geoff

 

[david.scarbrow]

Dave, Geoff, I've just arrived home from work...sorry about the lateness of this reply.
Dave my calibrations was correct and set up to match the actual Lipo voltage metered seperately (12.65 Volts). I had the 1st warning set up for No Load = 11.1 Volts, Loss = 0.1 Volts, Loaded = 11.0 Volts / GH & Land. The 2nd warning I had set up for No Load = 11.0 Volts, Loss = 0.1 Volts, Loaded = 10.9 Volts / Descending.

Geoff I have now reset it as per your suggestions...No Load = 10.6 Volts, Loss = 0.1 Volts, Loaded = 10.5 Volts / GH & Land. The 2nd warning I had set up for No Load = 10.3 Volts, Loss = 0.1 Volts, Loaded = 10.2 Volts / Descending.

Geoff, I see your point on considering 4s batteries but why ? eCalc throws a wobbly when I put 4s into the equation.

On another point that I've also got to consider soon is the performance difference between the weight of 1 battery versus the weight of 2 batteries.

 

[quadcopters]

Dave, Ecalc is not always accurate for me . Sometimes it is best to do trial and error .