Best battery pack for cinestar 6 with movi m10?

Discussion in 'Cinestar 6' started by Rony Varghese, Feb 3, 2015.

  1. Rony Varghese

    Rony Varghese New Member

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    hi,

    I have cinestar 6 with movi m10 with cannon 1D . I use turbo ace 10000 mAh, 6 cell, 22.2 V 15 C battery.
    I have naza autopilot and use gcs to monitor the battery.

    On GCS, it shows the battery as 24.8; as soon as i take off; the voltage drops to 22.7 V. Meaning 2.1 V is used just for take off. The cinestar 6 with the movi can not fly beyond 21.3 V.

    This means i have only 1.4 V for flying; I am currently getting only 4 min of flight time with slow manoeuvres.

    Can anyone please help on how to reduce the voltage drop in take off ?
    1) Maybe a battery with higher C rating ?
    2) Should i get a 16,000 mAh battery for added flight time ?

    Finally, When i physically check the battery (using battery checker) the battery shows 22.2 V instead of 21.3V as seen on GCS, any ideas would be great on how to increase flight time.

    regards,

    ron
     
  2. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    Hi Ron, welcome to the forum.

    If it's not too much trouble, would you be kind enough to change your user name to your real first name and last name, please? The reasons for this (and how to do it) are explained here: http://forum.freeflysystems.com/index.php?threads/real-names.497/

    I'm afraid your mental model of "voltage" is not quite right. The battery voltage will vary depending on the amount of electrical load and the amount of current that the battery is supplying -- it is quite normal. Think of it as water pressure from a faucet dropping when you turn on the garden hose. So the copter is not "using up" voltage -- it's merely a reflection of the amount of load. And when you land, the battery "recovers" a bit, so you will see a "no load" voltage that springs back up a bit.

    What you need to be concerned with is the amount of power that is use -- and that is measure in either Amp/Hours or Watt/Hours (where a watt is 1 volt x 1 amp). Voltage, as I say, is not the unit to worry about, because it acting as a general indicator of the battery's health -- because voltage does tend to sag as the battery is discharged.

    Check out: http://rathergoodguides.com/document-guides/rgg-to-comparing-certain.pdf -- it will, I hope, give you a better idea of what's going on, albeit with 4S batteries. (4 cells in series).


    Thanks

    Andy
     
  3. Jason Smoker

    Jason Smoker Active Member

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    what motors and props are you using?
     
  4. Rony Varghese

    Rony Varghese New Member

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    Hi Andy;

    This is my real name; i do not understand why you feel otherwise. You can email me if you want any proof like driving license; seriously this is my real name.

    Thank you for the link for on comparison and what power is. I am not taking about mental picture but from actual flight data.

    Power is what i need to be worried about but how can i see how much power is given from my battery ? only way to check is the voltage (P= VI) where I, current from the battery can not be calculated in flight.

    From my previous flights; i found that at 21.3 V; the battery simply didnt have enough current sent to motors giving them the power to spin fast enough to maintain flight.

    Hence calculating the difference between the voltage before take off to the voltage at landing; gave me the amount of energy that i can draw from the battery pack ( because V is directly proportional to I - V=IR; where for a given system R, resistance would not change between successive flights/ for a system) (energy from P=E/t and P=VI)

    Sorry; i am new user but all i was asking if could please suggest any better batteries that i could use to increase flight time. My current battery is 10000mAh 15C 6 cell and it is giving me power for only 4 min flight.

    Should i look for a battery with a higher C rating ? I do not completely understand this; from research i found it is given as the factor with him i can get max power intermittently- for ex - i would get 15*10000 = 150000 W ) - MAYBE A 16,000 mAH 25 C battery is better?

    Or should i discharge my current batteries and cycle them; maybe something is wrong with my current set of lipos?

    my take off weight with the batteries is 8 kgs.

    regards,

    rony
     
  5. Rony Varghese

    Rony Varghese New Member

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    Hi Jason,

    I am using carbon fibre rotors. I am not sure of the motors; but the motors have been labelled turbo ace.

    thank you,

    rony
     
  6. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    Sorry for your confusion! Your user name was being shown as Rony V. That was not your full name -- and that was what I was asking you to change. Thanks for doing that.

    What most people do would be to use an On Screen Display will shows the number of milliwatts consumed by the flight thus far and thus can tell you what I think you're looking for.

    What brand of batteries are you using?

    You are correct that Ohm's law (and Watts Law) are at work here, but the problem is that a batteries voltage will change under load and will "bounce" back when you remove the load -- it will even increase slightly after you land and the battery "recovers" somewhat. Of bigger concern is that you never want to take the battery down to below 3.3 volts per cell. So for a 6 cell battery than means 18 volts.

    You can use the battery voltage as a proxy for the remaining battery capacity as you can see from the discharge curves in the document for which I gave you the link.

    That does seem quite a short flight time for that weight. What ESC, motors and props are you using? Also what is the ambient air temperature when you fly?

    You could consider using dual 10,000 mAh batteries, but there's always the Catch-22 that then the weight of the aircraft increases, but you should see a net gain because the batteries do not have to work as hard.

    The C rating is the theoretical "Capacity" of the battery in units of amp/hours. So your 10,000 mAH battery has a C value of 10. That allows one to specify the maximum charging rate (typically from 1C (10 Amps) to 2C (20 Amps), depending on how kind you want to be to the battery and how much charge you want the battery to store. The lower, gentler, rate allows for more power to be stored. You will also find that vendors state the maximum discharge rate in units of C, e.g. 25C (250 Amps).

    Again, if you go to 16,000 you will find they weigh more -- you will get an increase in flight time but it will not be proportional to the increase in capacity because of that weight gain.

    DO NOT DISCHARGE THE BATTERIES -- at least do not do that if you mean take then down below 3.3 volts per cell -- you will destroy the batteries if you do that. Certainly take them down to storage charge of 3.7 volts per cell -- in fact you should, as the name implies, store them at that voltage if you're not going to use them for periods of 24 hours or more.

    Hope this helps.
    Andy
     
  7. Jason Smoker

    Jason Smoker Active Member

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    i going to go with Andy theory adding batterys as above but it also could mean you are under powered for your weight you want to carry! I am thinking your motors/props dont give you enough power for your flight you want. You might want to consider upgrading your motors and getting biggest props on cine 6 which i believe are 15inch for a standard size cine 6
     
  8. Rony Varghese

    Rony Varghese New Member

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    Hi andy and jason,

    thank you for the fantastic replies; i am not sure about on screen display that shows amps but will have a look through the web to find it. I was going to discharge batteries completely and charge them (cycle) but now i will never do it. thank you.

    my cinestar 6 is standard size with 15 inch carbon fiber prop. (the maximum)
    The motor is from turboace (http://www.turboace.com/ta-cw6-22brushlessmotorandmotorcapforturboacecinewing6.aspx)
    The battery currently used is turbo ace 10000 mAh, 6 cell, 22.2 V 15 C battery.

    I found 16,000 mAh battery from gen ace weighing 2kg, hopefully it will give considerably better flight time; i need be at min 10 min flight time.
    The ambient temp was 21 degree celius with wind speed of 7 knots.

    I must be doing something wrong, my total take off weight is less than 9 kg always and on youtube i find videos where people lifting 13 kgs with greater flight time.

    regards,

    thanks once again

    rony
     
  9. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    My first thought is that the motor are the issue. I've not tested those -- what Kv rating are they?

    Andy.
     
  10. Jason Smoker

    Jason Smoker Active Member

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    I cant find the specs for the motor?!?
     

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