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Thread: H3-3D equipped QAV400 @ 4S, what's my best strategy for 12-15 min runtime? At 6 now.

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    H3-3D equipped QAV400 @ 4S, what's my best strategy for 12-15 min runtime? At 6 now.

    Hey guys,

    This is my first real build, but I am a serious cinematographer trying to get a solid platform for arial shooting and music video content. So far so good, been getting some amazing footage:
    https://philymack.box.com/s/swkv5hodtv0dchf16y7l

    This is how I'm set up:
    • QAV400 frame

    • Lumenier 2216-9 V2 1100kv motors

    • Naza-m V2 with GPS and iOSD Mini

    • Zenmuse H3-3D gimbal with Hero3+ Black

    • Dragonlink UHF system and mini-receiver

    • ImmersionRC 600mw vtx

    • Graupner e-prop 8x5 propellers, also APC 8x4.5 props(+30sec runtime)

    • Lumenier 5200mah 4s lipos


    The only caveat: currently my heavy (estimated 1750-1800g AUW) QAV400 is yielding me around 6 minutes per 5200mah 4S pack. I must get this to at least 12 minutes reliably while still carrying a gimbal, and I can spend a little to do so. Right now in my head, it's super important to have a longer runtime for the things I'm doing with this frame, so I'm weighing all options that I vaguely know about:

    Option 1:
    Bigger(500? 540?) arms, 740kv pancake motors and 10-12 inch props, keeping the same batteries. I'm down to do this, although I really like how my QAV400 fits in a carryon-size bag at the moment and I can travel easily with it. Bigger arms means this may be a no go.

    Option 2:
    Drop to 3S batteries of a larger capacity? Is this even viable? I have six 4S 5200s and 2 4S 3300s that I'd really like to use, though.

    Option 3:
    Sell the whole rig and get a Phantom 2 or Inspire 1. I hate thinking about this, but these are proven(well, the Phantom is) for carrying small cameras, are impossibly (comparative to my QAV)lightweight, can last 12-18 minutes in the air, and fit in carryon luggage. Even if not one of the DJI things, is there another frame that will benefit me more?

    Option 4:
    ??? Smaller motors, same arms? Weight reduction somehow?


    I know my 1100kv + 8 inch props with high pitch + 4S setup is built for an acrobatic flyer and thus insanely inefficient to be lugging 1800g - I bought the frame already equipped with this basic setup from someone else.

    What do you guys think I should do in this case? I'd love to either spend ~$500 give or take, or sell and work on a different frame entirely.

    Also, stupid question. I have my low voltage alarm set at 14.8 and land as soon as I hit it. After resting, my batteries are always at around 3.8v-3.84v per cell = 15.2v. Am I safe to fly this to a load bearing voltage of lower than 3.7v per cell if it settles to something higher? If so, I know this is costing me a minute or two. Just want to make sure I'm doing this right.

    Thank you in advance for the advice and happy holidays!

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    With that weight there's no way to get your existing frame up to the time you want. Larger batteries or changing the S value won't help. The only thing that will do it is larger, slower props.

    I'm not sure if going to a QAV500 frame would do it for you. I have one that's not carrying a gimbal and it just barely reaches your target flight time.

    You might want to look at one of the Tarot frames. They can swing much larger props and are decently built. You can easily hit your target flight time (and maybe more) with a Tarot quad.

    As to your voltage alarm it's typical when a cell is under load its voltage drops. The better quality or higher discharge rating of the cell the less it will happen. Since you are running your 5200 mAH cell down in only 5-6 minutes you are drawing a LOT of current. And it may be that the sensing of your voltage alarm isn't really accurate. I usually run my 4S batteries down to the low 14 volt range while flying and be in process of landing as the voltage drops below 14 volts. I want to be on the ground at 3.5 volts per cell, under load. I should add I've calibrated my OSD and know that the voltages it's showing me are accurate.

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    i need to do a test for you with my 3 axis gimbal attached, but without it i am getting 15+ minutes with f450, fpv gear and 2216/1100 motors on 4s 4200 down to 80%, but i am using 9.47sf props which arent recommended as they are not rated for the rpm, ive flown many packs like this in gps mode which is far less aggressive and they are holding up. i do have some 9x45mr props to try, with the gimbal, i also agree with otherhand about flying down to low 14v, how much ma is your pack taking to recharge?

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    Yeah it seems like you are landing with a lot of voltage left.I normally land at 14v on 4s and that puts me at 80% used.How many mah are you charging back into your batteries? I agree that getting to 12min with that setup isnt likely spinning the fast motors and 8" props.
    Most of the money I made this year I spent on FPV,the rest I just wasted.

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    i tested it with the gimbal and landing gear on all up weight is almost 1800grams, i flew it down to 14.1-14.2 volts and used 3500 ma of my 4200ma pack( a little more than i like) and landed at 10 minutes 55 seconds. i did have some vibes in the video with the sf props and it was breezy. so i think if you can get 9 inch props and keep it light as possible with 5200ma you may come close to 12 minutes?

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    Quote Originally Posted by OtherHand View Post
    With that weight there's no way to get your existing frame up to the time you want. Larger batteries or changing the S value won't help. The only thing that will do it is larger, slower props.

    I'm not sure if going to a QAV500 frame would do it for you. I have one that's not carrying a gimbal and it just barely reaches your target flight time.

    You might want to look at one of the Tarot frames. They can swing much larger props and are decently built. You can easily hit your target flight time (and maybe more) with a Tarot quad.

    As to your voltage alarm it's typical when a cell is under load its voltage drops. The better quality or higher discharge rating of the cell the less it will happen. Since you are running your 5200 mAH cell down in only 5-6 minutes you are drawing a LOT of current. And it may be that the sensing of your voltage alarm isn't really accurate. I usually run my 4S batteries down to the low 14 volt range while flying and be in process of landing as the voltage drops below 14 volts. I want to be on the ground at 3.5 volts per cell, under load. I should add I've calibrated my OSD and know that the voltages it's showing me are accurate.
    You're still airborne when you see 13.9v on the OSD? Maybe I am landing too conservatively, I went to the mountains yesterday to shoot some areal video and landed at 14.3v loaded each time, lower than my usual, and I was getting a decent 8 minutes! Had a few 6 min runs too but I was a bit more aggressive. My resting voltage was 3.78-3.79v per cell. I thought going under 3.75v per cell was a no-no?

    Quote Originally Posted by sparkyincali View Post
    Yeah it seems like you are landing with a lot of voltage left.I normally land at 14v on 4s and that puts me at 80% used.How many mah are you charging back into your batteries? I agree that getting to 12min with that setup isnt likely spinning the fast motors and 8" props.
    Quote Originally Posted by Farmernz View Post
    i need to do a test for you with my 3 axis gimbal attached, but without it i am getting 15+ minutes with f450, fpv gear and 2216/1100 motors on 4s 4200 down to 80%, but i am using 9.47sf props which arent recommended as they are not rated for the rpm, ive flown many packs like this in gps mode which is far less aggressive and they are holding up. i do have some 9x45mr props to try, with the gimbal, i also agree with otherhand about flying down to low 14v, how much ma is your pack taking to recharge?

    i tested it with the gimbal and landing gear on all up weight is almost 1800grams, i flew it down to 14.1-14.2 volts and used 3500 ma of my 4200ma pack( a little more than i like) and landed at 10 minutes 55 seconds. i did have some vibes in the video with the sf props and it was breezy. so i think if you can get 9 inch props and keep it light as possible with 5200ma you may come close to 12 minutes?
    Well, sometimes I see 2800mah-ish going back in, sometimes I see almost 5000mah going back in. I have an iCharger 306B, and I usually parallel charge two packs at 1C each (10.4amps total), but even when I solo charge them I feel like the mah returning to the pack isn't accurate - is it supposed to be?

    Your runtimes are crazy for being nearly at my weight, same motors, and a smaller pack! Could it just be my props?

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    i would think you should be putting about 4200ma back in after a flight, are the cells balanced and charging to 4.20 each?

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    Quote Originally Posted by Farmernz View Post
    i would think you should be putting about 4200ma back in after a flight, are the cells balanced and charging to 4.20 each?
    Yeah they are - I do a balance charge every time and they all end up at 4.19-4.20.

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    maybe 9 inch props make all the difference then, or you fly far more aerobatic than me.

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    Quote Originally Posted by fs454 View Post
    You're still airborne when you see 13.9v on the OSD? Maybe I am landing too conservatively, I went to the mountains yesterday to shoot some areal video and landed at 14.3v loaded each time, lower than my usual, and I was getting a decent 8 minutes! Had a few 6 min runs too but I was a bit more aggressive. My resting voltage was 3.78-3.79v per cell. I thought going under 3.75v per cell was a no-no?

    Well, sometimes I see 2800mah-ish going back in, sometimes I see almost 5000mah going back in. I have an iCharger 306B, and I usually parallel charge two packs at 1C each (10.4amps total), but even when I solo charge them I feel like the mah returning to the pack isn't accurate - is it supposed to be?

    Your runtimes are crazy for being nearly at my weight, same motors, and a smaller pack! Could it just be my props?
    My custom is to be in the process of making my final landing descent when I see the OSD voltage cross below 14.0 volts. That gives me a small cushion for mistakes. A minimum operating voltage for LiPos is sort of a religious thing for people and you'll get some strong opinions. In general, the lower you discharge them the longer they'll last. I think the damage really starts to mount around the 3.1 volts per cell range, so for a lot of people 3.5 volts gives a good safety margin. I think if you were landing at 14.3 volts (if that's accurate) you could have flown a bit longer. Not a whole lot more, maybe a minute of gentle hover. Once the voltage gets near 14 volts it can drop fast.

    You say your resting voltage is 3.78 to 3.79 per cell. Storage voltage is around 3.80 volts so you aren't really flying it below storage voltage. Again, your LiPo will really like you for treating it that well, but you could run it down a bit more if you need the flight time.

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