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Dual Batteries

Discussion in 'General Discussion' started by sundance2013, Sep 18, 2013.

  1. sundance2013

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    Anyone flying with dual batteries? Does the Phantom's performance suffer much from the added weight?
     
  2. netphreak

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    It flies like its a little fatter, but no real change in the flight performance. I get around 20 minutes when I run dual batteries without any other mods.
     
  3. sundance2013

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    Wow, that is all 20min. I thought dual batt. would give you more than that. That is only like...maybe 5 min. more than one batt. isn't it?

    What about the 2700/2800 mAH batt. Any idea what kind of time you would get with those? I assume you are using 2 2200mAH batteries?

    Thanks
     
  4. rilot

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    It's all about weight. You only get about 50% more flight time for 100% more battery.
    I get about 12 - 14 mins with dual batteries, gimbal, fpv tx etc.
     
  5. MrMediaGuy

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    I don't know that anyone has ever done formal testing, but my guess would be that the addition of a second battery with no other payload probably gives you a pretty good return -- maybe 70% more flight time. You're still well under 1000g which is the design spec for "normal" flight. As you start to get past that, whether by adding a third battery, or a gimbal/camera/VTX/OSD/refrigerator/entertainment system, there is an increasing law of diminishing returns as you approach "zero" flight time (e.g., inability to lift off at all) because the motors become increasingly inefficient as you reach that point.

    Someone could, with probably 3-4 data points, extrapolate a pretty accurate curve that shows where the "sweet spot" is where additional flight time from battery is balanced by loss of time from additional weight. I've seen a few anecdotal tests that seem to show that for a "normal" Phantom (GoPro, maybe a gimbal, nothing else) that somewhere around 3200 mAh seems to be the best return on investment. A 4400 mAh pack it seems will fly only marginally (a minute or so) longer because the extra power is eaten up by the extra weight. (see for example: http://www.youtube.com/watch?v=MEzqPU6AYWs)

    Based on all that, I think a "somewhat ideal" combination might be using one of these:
    http://www.rctoys.com/rc-toys-and-parts ... ERIES.html

    Along with one of these:
    http://www.rctoys.com/rc-toys-and-parts ... ERIES.html

    That would be 4050 mAh in only 276g, which I think would be very close to the sweet spot. Maybe I'll have to try it and report back. :)
     
  6. Gizmo3000

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    it'll be interesting to see what kind of flight times people get with the soon-to-be announced Phantom 2, which will no doubt have a larger battery compartment.

    I've got a Phantom that flies for about 6 minutes on a 2200mah 3s
    but I get over 12 minutes on my F450 with a 4500mah 4s - and it weight considerably more

    tho I must say,. usually after about 8 minutes of flying, I'm ready to take a break.

    extremely long flight times might have it's benefits for certain kinds of shoots, but I actually prefer multiple shorter flights.

    If you're doubling up on batteries,. I've heard the 2nd battery doesn't necessarily have to be the same mah,. perhaps consider a lighter battery as a 2nd battery if possible.
     
  7. sundance2013

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    Does the F450 fit in the batt. compartment of the Phantom or are you hanging it on the outside? Anything special you need to do to use the F450?
     
  8. DeweyAXD

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    Hi sundance - i think there is a little confusion going on there. The f450 is another quadcopter... Not a battery. It is The bigger brother of the Phantom technically speaking. Google 'DJI F450' and you will see it. As you will see it is a frame style setup which allows much more customisation. The Phantom can only carry a 2000 mah batt in the internal compartment (well actually u can squeeze a 2250mah 'turnigy nano tech' in there).
    Using my dual batt fpv setup i can get 14 mins solid flight time..... The reasons why 2 batts don't double your flight time, as people suggest, is down to physics. Your stock motors can only spin so fast, the props can only provide so much lift etc. adding weight makes every component work harder which = more loss. With a gopro on board i very much doubt you will ever get more than 18 mins tops with 2 regular lipo batts. If you want 20+ mins flight time with full camera kit you will need a bigger rig, super light weight frame, big props, big efficient motors and a mother of a battery.... This is one of the many reasons why a pro hexacopter/octocopter is £6000 compared to a £500 Phantom.
     
  9. sundance2013

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    Thanks DeweyAXD, yep I was confused :lol: . Flying more than 18 or 20 min. as I think about it (and some have suggested) is a long time and one would get tired flying much longer than that. Also since I am new and don't have FPV and still freak out if the craft gets more than a 100m or so away, 10 min. for now is plenty, just looking to future modifications. For now just having a 2 or more batt. is fine.