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Interesting factoid

Discussion in 'General Discussion' started by fizzviic, Feb 23, 2014.

  1. fizzviic

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    I have a P1 as well as an early P2V. The early P2V battery is 4800mAh and weighs 252 grams. Two P1 batteries, each at 2200mAh together weigh 248 grams. In as much as the motors are the same, with the exception of the shaft threading for the self-tightening props, I can only surmise the much longer flight times must be attributed to one of two things:
    1) Prop design
    2) Lower battery discharge rate.
    The later due to the former.

    Thoughts?
     
  2. davemcm

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    Have you weighed both copters for AUW? Batteries included? Would give something to go on....
     
  3. ElGuano

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    Very interesting. I've seen the prototype 4400s and production 5200s, but never a 4800. Can you post a picture of it?

    Your weight numbers don't add up, I believe you have a few typos above? A DJI Phantom 1 battery weighs 172-174g. Two are about 345g, not 245g. Same with the P2V battery, it should be about 359g assembled (including cage and smart circuitry), not 250g.

    From what we can tell, the improvements to flight time are:

    1. Battery: ~50% - there's no question the 5200 is MUCH lighter than you can get stacking individual cells. I put together a 5400mah battery that weighs 397g, and that's about as light as I can make it. The P2V battery is <330g if you remove the circuitry, that's as light as my custom 4400 batteries, and in excess of 16.5mah/g, which I've not in any other 3S lipo. This is an EXCELLENT battery with amazing energy density and power to weight ratio. I hate that it is so expensive though. If it were <$90, I'd replace all my batteries with them.

    2. 9443 props: ~40% - the props are proven to be very good, and consistently provide ~20% more flight time over the P1's 8045s.

    3. Improved E300-derived ESCs and motors: 10% - that's the efficiency gain DJI suggests for the new ESCs and motors. These are running changes so later v1.1.1 Phantoms may already benefit from some of the enhancements, but all the P2s get the new stuff.

    The percentages are just my own rough estimate (opinions). But the battery is bar none the biggest factor here.
     
  4. fizzviic

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    Very interesting. I've seen the prototype 4400s and production 5200s, but never a 4800. Can you post a picture of it?

    Your weight numbers don't add up, I believe you have a few typos above? A DJI Phantom 1 battery weighs 172-174g. Two are about 345g, not 245g. Same with the P2V battery, it should be about 359g assembled (including cage and smart circuitry), not 250g.

    I have a 4400, 4800 is a typo. I weighed both the 4400 and 2 of the 2200s on a scale. It might be off. I'm also lugging a GoPro and FPV xmitter on the P1 along with some other goodies as well which ups the weight. Waiting for my set of P2 style props.

    Also contemplating swapping two of the motors for "black dots" and use the self tightening props.
     
  5. ElGuano

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    Ah, intriguing that you got a prototype 4400 pack with your Vision! I'd love to see the difference between that and the production 5200s, because again, those are out of this world. I'm absolutely certain your P1 battery weights are off by about 100g, though I obviously can't speak for the 4400-p2v battery.