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Short flying times..like 3 minutes until red..???

Discussion in 'General Discussion' started by Idahomojo, Oct 3, 2013.

  1. Idahomojo

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    I am flying a Phantom weighing in at 1250g. recently my flight times have dropped to 3 minutes until red flashing light. I have a fatshark FPV, an Arris gimbal, gopro hero 3, Futaba radio, and prop guards. Really not sure why the flight times are so short. Other than weight where should I look for issues?

    I have stock props on the craft. Do I need to upgrade to 3 blade props? I am not as much of a fan of carbon fiber as they seem a bit more dangerous due to how brittle they are. I have been hit by the stock blades with really no issues. But not to derail my first questions, what should I check that could be causing this battery draw?
     
  2. Gizmo3000

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    3 minutes is awfully short.
    I run about the same setup, tho no prop guards, and I get anywhere from 4.5 to 6 minutes depending on my flying.

    How well have you treated your batteries?
    and are you using the stock charger to charge?
     
  3. FangsCPO

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    It's time for new lipos. I would recommend the dronefly.com lipo (2250mAh 45C). You'll get about 5-6 minutes of flight time. I would also get rid of the prop guards once you get comfortable flying around. It's unnecessary extra weight in my opinion.

    The flight time that I quote is based on flying with carbon fiber props, ARRIS CM2000 v4 Gimbal and my HERO3. Good Luck!
     
  4. martcerv

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    What are the temps your flying in and altitude as being in very cold air and high altitude will have a big effect on both lift and Lipo battery capacity. Larger props will likely help as they help me quite a bit and you can also try some larger batteries especially at your weights.

    My flight times at 1150g using GWS triblades are around 8 1/2 minutes with 2200mah battery and 10 1/2 minutes with a 2700mah battery. I also have a 1300g 2x gopro hero3 setup that gets about 2 minutes less with both battery sizes, I have been trying a few other props with some odd results but still yet to find anything working better then those triblades with the next best props being 9045 carbon props sharing a similar profile to the DJI props. Best to try either of these props but your gimbal may also be draining a fair bit of battery so its hard to say. I am not using a gimbal atm but will use the XPG gimbal quite soon, this will keep my weight pretty much the same as my current single cam setup and I will have the option of flying it hardwired or with the small 50g battery it comes with.

    I am thinking the small battery may be a better option as Id rather carry the 50g then take more load from the main battery but this is something I will need to experiment with to see what works best.
     
  5. Peter Patricelli

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    Look at my "1 gram weigh = 1.2 seconds lost flight time" thread. I time a standard flight time by added weight...on a totally stock system...and your "SURPRISE!" finding of 3 minute flght is TOTALLY predictable. The 1.2 seconds figure ....for my stock system in my environment is a starting point figure....needs more testing and fine tuning. However, there IS an accurate figure out there as a starting point for a stock system/stock props. Some poo-poohed the concept but your question...and surprise....is exactly why I started pursuing this issue. My simple timed hover removes all the variables of more or less aggressive flying (more = more power drain = less flight time), variables of wind, etc. AND, unless my understanding of the aerodynamics of copters needs fine tuning, keeping the Phantom in the air in a hover is the MINIMUM power drain that is the base power/time loss underlying all other flight characteristics, manuvers, altitude gain, etc..

    Take martcerv's advice. I have already demonstrated to myself that 9"carbon fiber props give me @ 1' 30" at full load. So far, the GWS 9050 triblades are not working well for me. Martcerv is using upgraded motors. Whatever he is doing, his set up gives flight times that are top notch from my short experience.

    But weight...weight....weight is the single most controllable and pedictable thing that will drain flight time each and every flight, no matter the prop, battery size, temperature, wind, manivering, etc.. Before I decided to order the Tarot gimbal (which I chose partly because it was lighter..and cheaper...than the next step up) I ordered a simple cushion gimbal. It arrived weighing 64 g...the two plates were solid, thick aluminum..no attempt at all at minimizing weight. I got out the drill and swiss cheesed it...and removed 10 g. If my figure is anywhere near correct, in 6 flights I will have had a minute more flying time....just from that.

    Your phantom is not a draft horse or SUV. Someone once described copters, compared to fixed wing aircraft, as operating under brute force physics.....VERY inefficient....so power drain for each additional gram of weigt is a very steep curve.

    Peter Patricelli
    www.flyfishingfotography.com
     
  6. MrMediaGuy

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    Peter, great to see you collecting this kind of data and getting some usable insights for us all. I think what a lot of people forget is that the lifting ability of the frame plotted against weight is not a linear curve; when you are well under 1000g, you can add grams a lot more easily with very minimal effect on flight time because you are still well within the ability of the motors + props to deliver lift. Once you get past about 1100g, though, every additional gram carries a steeper penalty -- 1 second, 1.2 seconds, 1.5 seconds -- until you get to that very last gram at which the frame can no longer sustain flight at all. So the "last gram" you might say carries an infinite loss factor. :)

    The other Great Debate that we should be having is, how far down can you *really* fly your packs without damaging them -- or perhaps better said, where the detriment to the pack is balanced against the benefit of additional flight time?

    For example -- would you fly a $25 pack down to 8.9V if it meant you could have 11 full minutes of flight with a gimbal and VTX, but totally ruined the pack? Probably not. On the other hand, would you do it if it shortened the life of the pack to only 25 flights? At that point you just might, because the extra utility only "costs" you $1 per flight. :)

    I am discovering that some of the very well made packs from Thunder Power, MaxAmps, etc., are much more "tolerant" of being flown to far lower voltages than the recommended 10.7V (under load) and higher depletion than the "common knowledge" of 80 percent. As a test I have flown a Thunder Power 2700mAh pack down to 9.2V loaded (recovery voltage of 10.7) about 10 times and so far see zero impact on capacity -- but of course I need about 30 more flights before I can make any claims. :)

    However, just being willing to take that slightly larger pack well below the Phantom-default voltage levels took me from 4:45 (with stock battery and stock voltage settings) to 9:05 (stock props, Zenmuse, OSD, Immersion 600mw TX). Just using the larger battery with stock voltage settings only netted me an additional 30 seconds or so. But being willing to push the battery harder got me to nine minutes. Now, am I killing the pack? Don't know yet -- but even if I am, I'll pay $2 a flight to fly almost twice as long. :)

    Point is, I think even with the stock batteries we could all be flying significantly longer with minimal imapact through more aggressive voltage management.
     
  7. Peter Patricelli

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    MrmediaGuy,
    First, let me clarify my post above. I mean ADDITIONAL 1' 30" wit the 9" CF props over stock prop at a 364 gm load. If you read my post and look at the graphs....for the small number of points...from 0 added weight to 364 gms...the plot of lost time versus weight is quite linear. If this I correct, then 1st gram or 364th gram...same lost time. What happens beyond that....or with other props remains to be characterized.

    Thanks for pointing out I may be ruining my stock battery with my tests...since I ran them down to power failure. We'll see. I didn't want to complicate the testing with another battery...used the same one.

    What became perfectly obvious to me, trying to sustain a low hover as the battery neared exhaustion...is how variable it becomes, with surges of power when it will climb again...then drop, then climb again. I tried to keep it just off the ground so the sudden drop would be manageable. But I could easily have elevated 20' or more with a surge, then drop. Scary. Get them down.
     
  8. Idahomojo

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    I am looking at past videos and everything was the same except for the new Futaba transmitter. I don't think that would eat up any more power than the old one. Maybe my batteries all suddenly got damaged. Tough to figure it out.
     
  9. Roadkilt

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    This is an excellent post thread. Lots to learn here. Thanks guys.
     
  10. martcerv

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    Has the temperature dropped much recently? Using lipo batteries in cooler temps will give a pretty drastic cut in capacity. Either that or your lipo has died overnight or charger is playing up but it could also be a combination of all these.
     
  11. Idahomojo

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    I have 6 batteries and 3 chargers and the temp is fine. It's just that I was making 6 minute flights last week according to my videos and now I need to land at 3 minutes. Really nothing changed on the setup. I am wondering if something is shorting out draining the battery.
     
  12. Idahomojo

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    I took it out again just now and took off the gopro, prop guards, and the FPV transmitter. I left the gimbal on and powered. I did 3 mellow flights and still had to land at 2:45 - 3:15 on all 3 batteries. Anyone with any ideas?
     
  13. FangsCPO

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    Time for new lipos. Also there is a calibration section in the Naza software for you to calibrate your fail safe voltage using a fresh lipo. Give that a try.

    Sent from my SCH-I535 using Tapatalk 4
     
  14. jumanoc

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    Check your phantom power wires (where battery fits). If there is some cuts/ loosened conector or non tight soldering it will drain your battery power.
     
  15. Fdnyfish

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    I am having the same problem. I Has a small crash last weekend and I just replaced one of my ESC's.

    I also swapped out my motors to T-Motor MN2214-KV920.

    All powers up fine and I get a full GPS signal.

    I ran the phantom sitting on my desk with no Blades on and full throttle and the battery can go 10+ minutes and I get no RED low battery light.

    When I put on my stock blades, right after takeoff once I hit the 80% throttle I start getting a RED Flash like I have a low battery.

    I sometimes in the past seen a red battery while climbing, but the RED would go away once I started to hover.

    I do not think its a short in the phantom, or I would of seen the same results with no blades on.

    What do you guys think my problem is?
     
  16. Fdnyfish

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    I did a Advanced calibration, then a Basic calibration and it seems to wok fine now. I will keep my eye on it.
     
  17. UK_Paul

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    I'm a newbie to this site and it's my first posting.
    However, for may years, I was a "fan engineer" and the propellers on the phantom are just a set of 4 fans.

    You may find that you get a much shorter flying time if you fly the Phantom at full speed, all the time.
    The reason for this is that the amount of power consumed by the motors will go up by a ratio of what is known as "The Cubed Route"

    To save all the complicated maths it can be explained as follows.

    New Motor Power = Present Motor Power X (New quantity of air blown /Present quantity of air blown)3

    You have to blow more air to go faster (or hold up a greater weight)
    The important part of this is the "3" sitting at the end of the equation. (That's the cubed bit).
    It makes the absorbed power of the motor go very very high when the Phantom is flown fast and will therefore run the battery down very quickly. - For just a little bit more top speed you need a lot more power -

    You can see the same effect with the mpg (miles per gallon) performance getting much worse as a car is driven faster and faster, as the fuel consumption goes up the same way.

    None of this should detract from the previous comments relating to the subject, but if you fly it fast it will eat up battery power.
     
  18. dcoski

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    I was just wondering, anyway when I got my Futaba 8JA radio my receiver had two antennas. One antenna I ran down the opposite rear leg as my compass the other laid at as much of a 90 deg. angle inside the housing of the Phantom, but looking at it the end was very close to a bare solder joint. So I taped the end to the housing to keep it from touching the joint. I don't know if this could cause a power draw or something else even worse, but it might be something to look at.