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Battery observations/questions

Discussion in 'General Discussion' started by KMW, Feb 13, 2015.

  1. KMW

    KMW

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    OK, so my experience with lipo batteries has been with scale 4x4 trucks. The ESCs have a low voltage cutoff and you pretty much drive until the cutoff kicks in and change batteries. Never tracked voltages or worried about having reserve left in the battery. I run a 5100 mAh and can drive for almost 5 hours.

    So now I have a 1.1.1 that came with a stock DJI 2200 battery, and I just bought two Multistar 4000 batteries. Here is what I've observed. The 1.1.1 has a GoPro and prop guards on it.

    DJI 2200:

    Flying until the led starts blinking red has given flight times of just over 6 minutes. I got one flight to almost 8 minutes with super easy flying. These flights bring the at-rest voltage a few minutes after flight to 11.2. Recharging puts 1466-1522 mAh back into it. So it's not quite hitting the 80% limit yet.

    Multistar 4000:

    First off, I've only got three cycles on these so far.

    First cycle I set the low voltage alarm at 3.7V and flew until the red led flashed. This gave 7:00 and 7:30. The alarm never sounded. Upon landing the pack voltage read 11.3 and 11.5. Recharge was 1654 and 1545 mAh.

    Second cycle I set the low voltage alarm at 3.6V and flew until the red led flashed. Flights were 7:20 and 7:22. Pack voltage right after landing was 11.4. Alarm never sounded. Recharge was 1452 and 1492 mAh.

    Third cycle on one battery I set the alarm at 3.4V and flew until the red led was flashing steady, not just under heavy load. Flight was 8:07 and no alarm. Pack voltage after landing was 11.1. Recharge was 1885 mAh.

    Third cycle on other battery I set alarm at 3.6V and flew until the alarm sounded. Flight was 7:15, and the auto land function kicked in right as I was starting to land. Pack voltage after landing was 11.1. Recharge was 1694 mAh.


    So, it would seem that based on the charge going back into them, I'm not getting 80% of 4000 mAh out of them. Are they seriously overrated? Or just not broke in yet?
     
  2. joeflyer

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    My experience has been that all of the Hobby King batteries are seriously overrated.
     
  3. rebelyellNC

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    Hey KMW, while I don't have the equipment to tell how many mAh is going back into the Multistar 4000s, I can tell you they helped my Phantom 1.1.1 attain a whopping twenty minute flight time. Keep in mind this time is from actual liftoff to touchdown and I wait for autoland to be triggered, slowing increasing throttle until hovering is exhausted. That high flight time was with 9450 thrust boosted props and a GoPro mount but no camera.

    After adding all my FPV equipment, which includes a SJCAM SJ4000 camera, anti-vibration isolation mount, Flysight 400mw transmitter, DJI PMU V2, DJI iOSD mini; yesterday with the Multistar 4000 I got just seconds short of fifteen minutes. This was on an FPV flight that was 800+ meters out and the same back, plus some close in circuits watching the low battery warning and corresponding voltage on the iOSD mini readout.

    The AUW of the 1.1.1 is now 1248 grams, which is significant, but not too bad considering the fifteen minutes on a Multistar 4000. Some folks don't like them, but I bought three of them and don't even use the Phantom 2200mAh battery any more. I might mention that I have altered the settings in NAZA M Assistant for the second level voltage warning. It gave me a couple of additional minutes. Hope you can work this out and get all the time these Multistars have to offer...
     
  4. PhantomFanatic

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    Why the disparity in the results, using the same battery?
     
  5. KMW

    KMW

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    I believe some of the difference was due to wind and how I was flying. I was flying somewhat aggressively for these flights, with some good climbs, hard banking turns, etc getting used to the handling. The wind was off and on, and on some flights it acted like there was more wind up high as you could hear the motors changing sound more than at other times while it worked to keep position or heading. The 8 minute flight I was watching the leds more so I was lower and slower than the other flights. That's my theory at least. Like I said, I've never monitored this stuff before with my trucks, so I'm still trying to figure it out.
     
  6. KMW

    KMW

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    It was actually a post of yours that convinced me to get these batteries. What did you set your second level voltage to? What are your pack voltages after landing?

    My landing voltage was read from the alarm display right upon landing, so not much rebound time from under load.
     
  7. KMW

    KMW

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    I've had really good luck with them in my trucks, but I realize that scale crawlers don't put high c draws on the batteries the way flying does.
     
  8. rebelyellNC

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    Hey K, my most recent NAZA Assistant voltages are as follows

    level one 11.30 0.60 10.70

    level two 10.80 0.60 10.20

    These are the same settings that gave me just under fifteen minutes with full FPV gear.

    As for the pack voltages, I quit testing them after about two weeks of pulling my hair out (what little there is) when nothing seemed logical. I was using the individual cell alarm buzzer device to read cells and pack voltage and nothing made any sense. I even tried asking J. James on this forum for his advice and it was puzzling to him too. The resting pack voltage is always 11.0 or 11.1 after two to five minutes.

    I just watched a video last night on extending flight time and the user was down to 9.43 second level loaded in the NAZA software. I don't know if I'll go that low, but I am going to bump the second level values down a bit more.

    Same here man. All my flying before the FPV loadout was aggressive, trying to learn from my mistakes. And the wind here has been deadly the last two weeks. About twenty minutes after sunset is the only time I can fly, and that doesn't leave much light. After our winter storm next week, I hope things settle down a bit.

    Hope some of this helped...
     
  9. KMW

    KMW

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    Yeah, thanks! I think tomorrow in going to do a straight hover test and see what they get.
     
  10. rebelyellNC

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    Well, it's true, you will definitely get a number, but how practical will the results be doing only a straight hover. You might consider just flying some circuits, up and back, a rectangular pattern, a circular pattern, some ascents and descents, etc. Just not a lot of hot dogging. Aggressive flying was all I did for weeks after I got my Phantom (before the FPV gear), but then things settled down and I began to refine some of my operations, concentrating more on proper execution of a maneuver instead of how fast or wild I could do it.

    So sure the hover test would give you a number, and I wouldn't mind knowing what that would be, but for real world application, just some normal movements may provide you with more reliable information.

    Just my two cents, man. Let us know...
     
  11. KMW

    KMW

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    Well, we have 6-7 cycles on the Multistar packs now, and have changed the protections to level 1 at 10.6 and level 2 at 10.1. We're now getting 14-15 minutes to land with pack voltage at 11.1, and charging puts 3200 mAh back into them. That was with the GoPro in case, and no prop guards.

    Today I added a Walkera gimbal. With the gimbal, the GoPro without case, and no prop guards I flew one flight to 12:45 and was just barely hitting level 1.
     
  12. 4wd

    4wd

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    The times mentioned do seem pretty low unless you have gimbal and such draining it too.
    My P1 with supplied 2200 battery would usually fly for 10-12 minutes before any warning lights - with just an SJ4000 (gopro copy) directly attached.
     
  13. JKDSensei

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    Those are good times with a 2200.
    Best I get is 7:30 but I have my low voltage settings at the defaults to extend battery life.
    But I can comfortably go 1500 feet and back in that time (and loiter a bit)
    SJ4000
    54gr GPS tracker
    Anti Vibration Mount
    Flytrex Core 2
    Low Voltage Alarm
    Boscam FPV Transmitter & CP Antenna
    Prop Guards
    923g total weight