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Dual batteries, weight & Phantom limits

Discussion in 'Phantom 1 Discussion' started by steelpix, Aug 19, 2014.

  1. steelpix

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    I'm thinking about putting two batteries on my Phantom. I'm wondering what negative it would take on driving the motors that hard, not to mention the drivers on the circuit board.

    Any thoughts?
     
  2. OI Photography

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    You'll probably want to add the P2 props if you haven't already, to give you more lift to work with.

    The key is to keep the total weight of the Phantom, with battery/batteries and everything, to 1400g or less if possible, 1350 is even better but I know that can be difficult to hit with dual batts. Note that those figures are a bit lower when using the stock 8" P1 props.
     
  3. steelpix

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    I experimented yesterday with two batteries in parallel, straped to the bottom with velcro straps. Was able to leave the battery door open without problem. My usual flight are about 11 to 12 minutes not loaded with much of anything, sometimes a GoPro.

    This flight was 18.5 minutes. I wasn't driving it hard either as I didn't want to go to far with the batteries strapped. When I finally landed I felt the motors and they were warmer then usual. But that would make sense. More weight, more stress. Used the stock 8" props.

    Ron
     
  4. ElGuano

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    Re: Dual batteries, weight & Phantom limits

    12 to 18.5 is a good result. As long as your batteries are secured and to43 not using those carbon fiber "side saddle" mounts, it should be all good.
     
  5. Piso Mojado

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    What is the difficulty with the side saddle battery mounts?

    Thanks!

    Memo
     
  6. ElGuano

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    They put significant weight out to the sides, and they're directly in the prop wash of the rotors. This reduces efficiency/lift, and introduces dynamic instability that the FC has to fight to correct. It's also heavy and requires the use of a large parallel harness into the battery bay.

    The side saddles have been implicated in quite a few loss-of-control crashes, particularly on descent. They're just a poorly thought out concept and there are much better ways to achieve greater results.
     
  7. Piso Mojado

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    Thanks for the helpful response. Recently I simply strapped an additional 2200mah lipo to my Phantom. There were some problems with control, which I expected. I was surprised, though that on descent, some of which appeared spontaneous, that I couldn't prevent crashes even at full throttle. Would changing to 9" props with their greater lift help?

    Memo
     
  8. pierrelogic

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    Affirmative
     
  9. ElGuano

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    You need to be a bit careful with that. Generally, it should help. However, I found that the P2's 9.4" props are a bit less stable and crisp than the P1's 8" props. That's a reasonable and expected tradeoff given the greater lift and longer flight times of the 9" version. But whereas you rarely ever heard of loss-of-control-on-descent with the 8", it was a fairly regular complaint with the 9", to the point where DJI is now releasing a slightly revised "9450" props to help with heavily loaded craft and those who fly at high altitudes. There are a number of cases where the side saddle dual-battery mounts and the 9" props together accounted for a few crashes....
     
  10. pierrelogic

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    Just to clarify my single word affirmative response....

    "Resume time"
    All this feedback is based on about 180+ flights (so far) and the vast majority of them using CF props...just in case anyone wanted to know backgorund.

    CF props do increase flight time and provide greater lift than the stock plastic props. The question asked I took it at face value. I have zero experience using dual batteries setups and this thread was really about that. So please make that distinction when reading this.

    However, I have never had any instability issues whatsoever with my single battery setup on both smooth and very aggressive descents from high altitude. In fact I'm sure because of my use of CF props I prevented a couple of hard landings but hitting full throttle right at the end of a battery charge while descending to get that flare-out needed to soften the impact. I refer to those simply as close calls. :roll:
     
  11. Finncelt

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    To get more flight time I added the cf side mounts to which batteries are strapped with velcro bands. I have a tarot and gopro3 black, a flytrex and cables and a fatshark transmitter and 5.8 gHz CP antenna. DJI P2 props. AUW was 1450g. With paired Zippy 2200 mAh batts i could easily get 7-8 mins (+ or- 1 minute) for landing. With the gains dialled in, flight was stable if sedate. Fine for me as i want decent video. I am amazed at people getting longer times with only one battery! I must be doing something very wrong. To test this, I got some Turnigy 2800 from Hobbyking and stripped my bird down to the basic quad with
    - tarot gimbal
    - Gopro 3 black plus battery and fpv cable
    - fatshark transmitter, CP antenna and cables
    - 1 turnigy 2800

    AUW 1210g. Result? It flew like crap, the battery fits poorly in the P1 and i was lucky to get 5 mins. The gains were rubbish and the craft bucked all over the place. Admittedly it was windy and i had to keep gps lock on throughout. I tested again today with different gains in much calmer conditions but it was the same, wobbling and wandering both horizontally and vertically. I am confused.....

    Back to basics. No load, default P1 gains, P2 props on and a single battery. Let's see how it goes. Watch this space.
     
  12. Robert

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    I am new to this game. I recently purchased a new Phantom 1 as an introduction.
    The standard battery gave me approx. 10 min with the Go Pro attached.
    I purchased a Zippy 30C LI-PO 2800 battery but the flight time is only about 8 min.
    Can someone advise on the best way to achieve longer flight times.
     
  13. OI Photography

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    1. Start using DJI's stock props for the P2. You'll need to determine if your P1 has the motors that will let you use the self-tightening version or if you'll have to get the non-ST version. Those will add a good chunck of flight time, but will also make the Phantom handle/fly a bit different without adjustments.

    2. Get a better 2700-2800mAh batt than the Zippy...those are known to be poor performers and usually overweight for the capacity. Dinogy, Pulse, and Maddog all make great batts in that capacity range for the P1.

    3. Trim weight if at all possible, that's your biggest restriction on flight time.
     
  14. hedonist222

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    I put on an h3-3d zenmuse gimbal.
    And two batteries.

    I weighed the above + the Gopro3+

    Total weight: 1,330 grams

    Impressive
     
  15. steelpix

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    I asked DJI about using dual batteries and they said not to. They didn't go into detail though. Common sence tells you the motor work harder and get warmer, but at what limit or life of the motors does it effect.
     
  16. nestergaard

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    How can I see that on my phantom?
     
  17. Molokai

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    The main reason people encounter issues with dual battery mounts is because of the way they mount the batteries. Most people put them the wide way instead of the narrow way. With the narrow way, I NEVER encounter issues with lift or descent. Running dual 2200s gives me over 18 minutes of flight with no equipment.
     
  18. Clipper707

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    I saw 20+ minutes once with a Mad Dog 2700 battery and P2 props on my P1. It was a sedate flight with no payload.

    I'm convinced P2 props are the way to go, but both of my Mad Dog got puffy after about 3-4 months.
     
  19. ElGuano

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    20 minutes is a lot with a single Maddog, but possible. If you're seeing that regularly (and your batteries are puffing) you're most likely straining the battery and overdrawing it!

    I could get 30.5 minutes with zero payload and 5400mah on a lightened Phantom, and about 18 minutes fully loaded, but I have a lot of work done to mine. The side-wing battery mounts are everywhere but IMO they are a very bad idea, when paired with P2 props they have been implicated in a number of control loss events especially during fast descent. Some people have better experiences than others but there are definitely better ways to mount dual, IMHO.