Heavy lift (ok 5.8kg AUW)

Discussion in 'Electronics' started by Gary Haynes, Aug 26, 2012.

  1. Gary Haynes

    Gary Haynes Administrator
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    So I took a couple of test flights this morning flying a Nikon D800e. Here's the setup

    CS8, QC motors, 14x4.7 props. Flew with both a QC6200 4S and a Zippy 4S. Total weight was right at 5700g. Camera is 1300g with lens. 4400g for frame and battery.

    Almost immediately after liftoff my low voltage, set at 13.9, came on. Amps were running at an average of 64 amps.
    Flight time was right at 4 mins with very limited height or maneuvering. Battery's were pretty hot after flight. BL's were running about 60c and outside temp was 80F. After flight I checked the flight logs and highest amps on a BL was 11.0. Temps looked fine. I was about 10 points down and left on balance when I checked that. Throttle was at 129 for hover. Everything else seemed to be fine and all functions were normal.

    So a couple of questions to the group.
    1. Does this sound pretty normal? I flew my Hasselblad a couple of times a few weeks ago and don't remember getting the low batt alarm so quickly. Flight times/amps were about the same and it was about 900G heavier.
    2. Assuming that at 5S would help. I've already upgraded the FC board, etc and just didn't get a chance to fly my QC 5S.
    3. Would a higher C rating battery make any appreciable difference?

    And lastly I could always upgrade motors/BL Controllers but since I was hovering right at where I expected from ecalc not sure that it is a motor/prop issue.

    Looking forward to the wisdom from the group.
     
  2. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    Hi Gary:
    I presume you had the two LiPo's in parallel. I wonder whether there was current flow between them?

    I wouldn't have thought that the flight load would have caused the battery voltage to sag at 64 Amps. I noticed for hover/clime I was pulling 60 Amps with just a single QC 6200 LiPo and the Sony HDR CX760 on the 3-Axis gimbal.

    Do you see the same voltage sag if you fly with just a single LiPo?

    Sorry I can't add wisdom, only questions. :)

    Regards
    Andy
     
  3. Gary Haynes

    Gary Haynes Administrator
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    Andy

    Single lipo. I went back and looked at a log for the Hassy and that was running high 60 amps to about 70. Probably need to lower my alarm setting.
     
  4. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    Gary:
    Ooops. The perils of me being a literalist -- I took the "and" between the two batteries and you were flying with them both at the same time. Sorry about that.

    I have my LV alarm set to 14.4 and occasionally, if I do a sustained "scalded cat heading for the stratosphere takeoff" I get get a low voltage alarm to trigger.

    Andy
     
  5. Tabb Firchau

    Tabb Firchau Administrator
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    Hi Gary, my octo is currently 6.5kg RTF and I am running QC 3328, 4s9000mah Freefly flight pack (we will soon release these for sale) and I fly for 6 minutes leaving plenty in the tank.

    Hope that helps....It sounds like your batteries might be getting old and are no longer holding voltage under load? Also make sure the connector you are using is up to the task...I recommend an EC5

    Best,

    Tabb
     
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  6. Josh Lambeth

    Josh Lambeth Well-Known Member

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    This is good advice. My 4s 6200's are starting to get old and I am having the same issues. I recently bought one new 6200 and the difference between the new and old batteries is about 2 min. I get between 6 1/2 and 7 min of flight time with the new battery while my old batteries get me about 5 min. THe old batteries also drop voltage wise much quicker then the new one. It will be down in the high 14V range within 45 seconds of taking off and then just stays there during the remainder of the flight and just slowly drops down to the 14.0V warning by the end of the flight. Once I stop the motors the voltage on the pack will read about 14.8 so it's def. sagging a lot now. Sucks because I have only had these since April.

    Josh
     
  7. Gary Haynes

    Gary Haynes Administrator
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    Tabb and Josh

    What do you see as flight amps? I'll do some more flights this weekend and report back. Will also report back on the 5S.

    At 9000ma which is roughly a 50% increase in available juice and at 6min with left over that seems to align with what I was getting with smaller batteries. On recharge the Hyperion said I was at 23%. Don't have that many flights on any of my batteries.

    Anyone want comment on what they see on battery life, number of recharges? Or what your decision process is in retiring a battery?
     
  8. Josh Lambeth

    Josh Lambeth Well-Known Member

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    Average is mid to high 60amp range depending on the temps outside. I have however seen as much as 120 amps coming out of a decent! :eek:

    Josh
     
  9. Nick Kolias

    Nick Kolias Moderator
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    Gary, I'm using two 4S 45C 6600mAh thunder power packs in series (13,200mAh total) on my main CS8. AUW of the ready to fly frame along with 360° gimbal is 12.34lb without a camera. When we mount a 5 or 7D with a nice prime it's usually adds between 3.3 to 4.1lbs depending on the lens. When we mount a FS100 w/ 18-55 it's just over 3.5lbs and the little CX760 with big battery and various filters on the front is a little over 1.5lbs. With the DSLR's the average current during typical operations is between 65 & 80A. I've seen rapid ascents push over 130A. Normal flight time is a little over nine minutes with quite a bit of juice to spare. Things are warm after landing. With the little CX760 the typical current is 45 to 60A. I can fly 10.5 minutes with a nice safety reserve. Things are cool to barely warm after landing.

    The MK-PCB extension that flashes the LED's when it reaches a preset voltage (14v) can be helpful when tuning your system. I ran packs under typical conditions to determine how long it takes for the warning to appear then I set my TX timer for a minute less. I think a one minute reserve is prudent and it's comforting to have obvious, visual feedback that the packs are still okay while you return to land.

    Those packs have about 100 charge cycles now and they seem to be doing well. I've got twelve of them and it would be too big of a pain in the ass to log all the charge values but I do keep an eye on how many mAh get put back in and I'll probably retire them when I notice a significant reduction in capacity and reduced flight times.

    Would be interesting to hear what would happen in your case if you left all else the same but put a nice, new battery on there. I wonder if your packs are just kaput?
     
  10. Gary Haynes

    Gary Haynes Administrator
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    Thanks Josh and Seattle

    I doubt that my batteries are over 50 charges apiece. I'm going to dial down the warning.

    With the previous MK/MX20 software I went by time and if I saw the boom lights flashing that was also a good reminder. With the latest software and the voice command turned on I also get a voice alert for low voltage. Gets annoying if it starts and continues throughout the flight. Probably will drop it to 13.5 volts which is a pretty slim margin. Would be a nice improvement if we got voice warning for a set amount of amps consumed. Might be more accurate than voltage.
     
  11. Joe Azzarelli

    Joe Azzarelli Active Member

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    Yesterday's flight test: CS8/360, QC's 5s 6200, CX760 - weighing in at 12.25lbs AUW. This was at noon in Tampa, so about 90°F ambient. Heatsinks installed. Nice 9 minute flight with volts to spare. Mostly hovering.
    flight 083012-3.jpg
    Joe
     

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