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5400mah for Phantom 1

Discussion in 'General Discussion' started by ElGuano, Jan 22, 2014.

  1. ElGuano

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    So, I finally got a new set of maddog 2700 batteries. I had a doubled set a while back but had barely taken it out for a few test flights before giving it up to a friend. Since then, i've been running my 4400s and they've provided more than enough flight time. But as I prefer missing the dji 2200s over 3rd party batteries. Each 2200 costs ~$25. Mad dogs are only marginally more so I'm getting 1000mah for $10 difference. I'll take it. Besides, it would give me a chance to test it with 9443s and FPV gear attached.

    I wired them up as a 3s2p, 5400mah. It's monstrously big (and heavier than I remember). On the first test flight this morning, compared to one of my 4400 packs:

    4400 3s2p: 17 min 01 sec, 3.6/3.65/3.65 (10.9v) (1193g auw)
    5400 3s2p: 21 min 05 sec, 3.65/3.67/3.70 (11.0v) (1268g auw)
    Difference: +24%. 

    The dual maddog pack weighs 397g. Before surgery each one was 202g. I remember the last pack I made was lighter, and my 4400s shed 18-20g when doubled.

    The 4400 was drained to 19% (3570mah back on charge). Maddog isn't going to be charged until tonight.
     
  2. ElGuano

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    Just a few pics:

    Next to a 4400. This is gonna be a biggun...
    [​IMG]

    All done. It seems the patient survived.
    [​IMG]

    Still heavy.
    [​IMG]

    Look at what you need to do to get it to fit a Phantom:
    [​IMG]
    [​IMG]

    AUW: 1268g
    [​IMG]
     
  3. OI Photography

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    I've been waiting for you to get around to doing that :cool: I doubt I'll ever go as far as trying to marry batteries like you do (trust me, it's better for everyone that way), but I was anxious to see if the maddog 2700's are as great that way as they are individually.

    I noticed something Monday night after a random flight that makes me think the maddog batt I was using might be delivering more than the rated 2700mAh capacity: after the flight my voltages bounced back to ~3.75/cell within a minute (almost immediately, really) and leveled there (as I intended with my voltage settings), but when I charged it afterwards the charger says it returned 2635mAh. So am I pushing it too far, or is this one just better than it's labeled? Btw the flight itself was a record for me, 16:21 on a nearly-naked P1 with Vision props (and T-motors), no gopro but the frame holder was mounted and I have some minor extra components inside. AUW was 945g.

    I'm ordering two more this week, I'm planning to test the same setup above with the addition of a 2nd batt strapped to the outside, I'll compare those results to the ones you get with your frankenbatt ;)
     
  4. LeoS

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    That's awesome!

    This puts Phantom 1 on even flight time vs Phantom 2 variants and makes it even more attractive due to the much cheaper battery (and arguably it's higher reliability due to all the revisions).

    Btw what do you think about using phantom 2's body to get larger interior space? Someone needs to 3D-print the lid for the battery opening though.
     
  5. ElGuano

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    If you have a smart charger, you can plug in the battery, discharge it (it'll go SLOW so budget a lot of time) and then charge it to full. That'll give you a good indication of true capacity. 3.75 resting is a healthy level, the mad dogs will bounce to recovery voltage fast because they have low IR and I think a higher-than-labeled c-rating.
    I ran a single 2700 with gimbal and fpv before combining the packs, 12:05 @ 1081g; sounds like your 16:25 is right in line with that. My last naked-phantom flight was with 4400s, it was 936g and 22min. I'm going to rerun that with 9443s and the 5400 soon, my optimistic calcs would put me at about 29 minutes. Fingers crossed...
     
  6. ElGuano

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    I'll post up pics of my current battery door, it fits but it ain't pretty. I think the p2 shell is a direct fit, but you'll need to drill a new hole for the LED light, which the p2 doesn't need. I'd think about keeping the built-in battery plug too, in case you want to use genuine p2 batteries in the future (they apparently work fine with the p1 guts).

    From my weights, it seems the p2 battery does have higher energy density. It's 360g for 5200mah, plus charger/balance circuitry and a plastic cage. My heat-shrinked 5400 naked is almost 400g and my 4400s are 320g. We really need a brave (wealthy) soul to tear apart a p2 battery and weigh/test the cells.
     
  7. LeoS

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    Cool.

    40g is less than 1 minute of reduced flight time though... and what's the cost of a pair of Maddogs? $60?
    That's about 2.5x cheaper :D
     
  8. ElGuano

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    Yeah, the cost is a no-brainer. But keep in mind you're getting up there in weight with a 5000+mah battery and 40g can be a full fpv setup, a GPS tracker, a couple of LED pucks or light strips, etc. IMO flight time really becomes a serious tradeoff at or above the 1300g range.
     
  9. OI Photography

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    Sounds good, doing that now. My Accucel-6 discharges to 9v by default on a 3S, I assume I should leave it there?
     
  10. ElGuano

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    3.0v per cell under load is the absolute minimum, and it really falls off a cliff at that point, as in exponentially. It should be fine so long as you charge it up immediately after that, but I personally chicken out and go 3.3v instead on the VERY few times I have bothered testing, and live with knowing that I may be measuring 95% capacity instead.
     
  11. OI Photography

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    Roger that. I feel confident about the maddog's so I'll push it to 3.0 this one time ;) I will be charging it as soon as it's finished discharging, so it should be ok. If not, I'll know where the line is next time.
     
  12. ElGuano

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  13. PJA

    PJA

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  14. ElGuano

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    Look at the maw on that thing. Mine isn't pretty, but it's less conspicuous than that :O
     
  15. LeoS

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    That's crazy :mrgreen:
    I was thinking of reusing Phantom2's body to keep the cost down and they're easier to be found and just patch up the battery opening with a custom piece.
     
  16. OI Photography

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    Nice, I kinda like the full "hanger-bay" look on the Phantom ;) After looking at your pics of the soldering on the batt cells, I think I may give it a shot someday. Someday.

    I finished discharging/recharging my maddog batt. The charger stopped the discharge at about 9.4v because the cells were a bit unbalanced at that point, but even when recharging from there, the battery took back 2911mAh.
     
  17. ElGuano

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    That's the thing. With a 4400, the stock Phantom door covers the entire opening. Nobody can tell you're running twice the battery (but for the longer flight times). With a 5400mah, you've gotta carve out 5mm on each side of the door to get it to fit. At that point, why not go a 3D printed replacement piece and fit whatever battery you want? You don't need to go to the trouble (and risk) of soldering up a 3S2P, just buy a 5000mah and toss it in.
     
  18. ElGuano

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    That's really impressive. It helps explain why you can get ~25% performance increase out of ~23% additional sheet capacity. Guess it's actually closer to 33% additional.
     
  19. OI Photography

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    It's also a clear demonstration of the difference between a cheap and quality batt. I guarantee you the 3000mAh Zippy's I have don't even match the true capacity this maddog is delivering...at 45g less.
     
  20. ElGuano

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    Just doing a quick browse on HK, another reason why dual-DJI 2200s or Maddogs may be a better idea than just dropping $30-50 on a big 3s pack: weight.

    A 4000mah pack weighs between 420-450g. A 5000mah pack weighs between 490-550g.

    The dual-DJI 4400 weighs 320g, and dual Maddog 5400 weighs under 400g.That's a huge difference.