Batteries, 4S vs. 6S

Discussion in 'Cinestar 8' started by Dave Tranquilla, Jan 9, 2014.

  1. Dave Tranquilla

    Dave Tranquilla New Member

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    Good Morning, my first post here. We have A CS8 and are looking to carry more weight. Not a new idea. I am looking at QC and see their HL parts list. My question is on batteries. Why and what are the advantages of using the 6s battery to power the HL?. Can a 4s be used or will damage occur?

    Thanks in advance! Dave
     
  2. Steve Overstreet

    Steve Overstreet New Member

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    Rotational speed! Since KV is rotation per volt, the blades are faster not to mention the other law of electricity; high voltage means less amps used for the same work.
     
  3. Steve Maller

    Steve Maller UAV Grief Counselor

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    Welcome, Dave.

    First, a bit of info. 4S and 6S refer to the number of cells in the battery, and therefore the voltage produced by the battery. Each Lithium Polymer cell can be charged up to a nominal voltage of 4.2VDC. So a fully-charged 4S produces 16.8VDC and a fully-charged 6S produces 25.2VDC. And if you have the right components, a 6S battery pushing the same current level (amps) will produce 50% more watts of power than a 4S battery.

    Now, in the case of copters, it is generally considered these days that the 50% increase in net power available to a 6S system is A Good Thing. However, you should be aware that many components of the stock Cinestar 8 platform are not capable of using a 6S battery. The “RTF” configuration available from Quadrocopter, for example, is limited to a 4S battery. Upgrading the copter to 6S is a non-trivial thing, and there are many different ways to skin that particular cat.

    There are numerous active discussions here that chronicle many folks’ journeys down that particular road. Including me, presently. I elected to replace virtually every electric portion of my Cinestar (motors, power distribution board, flight controller) in order to accomplish this. I’ve got almost all the pieces here, and soldering should commence next week.

    And to answer your question, I believe that a 6S copter can run at 4S with no modifications if you don’t need all the oomph (like if you’re flying a small camera).
     
  4. Dave Tranquilla

    Dave Tranquilla New Member

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    Thanks for the quick replies. Really appreciate it. What I suspected seems true. For a truly more powerful copter sounds like I will need to upgrade to the 6s batteries, as well as motors, esc, fc board, booms, etc....

    A followup question. My current rig: 3328 motors, 4s batteries, and MK PDB and FC is currently seeing pretty high temps when flying a Canon 5Dm3, has anyone seen lower temps by installing the new MK Double v 3.0 PDB?
     
  5. Steve Maller

    Steve Maller UAV Grief Counselor

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    Dave,
    Those new PDBs are just arriving and I haven’t seen anything beyond Holger’s (the guy who makes them) posts. We’re all taking a leap of faith! :eek:
     
  6. Dave King

    Dave King Well-Known Member

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    Dave you are seeing higher temps because the QC 3328 motors are overworking at that weight and pulling a lot of current. While the board might be able to abosrb the current better it doesn't necessarily mean that you motors will run cooler so IMO it would be a bandaid and you would still have risks of motor failure. I was looking over a lot of data to see if I had ever had to build another 4S what combination what would I go with. Here's some thoughts I have.

    A typical CS8 with a 5D MKiii will have a GAW of about 6.3K and needs about 793 grams of thrust. The Tiger MT4008 600KV motors should get you hovering around 55% throttle if you can use 15 inch props and 500 mm booms. With 14" props and the stock 450mm booms you would probably be hovering around 61-62% throttle which doesn't give me much head room for heaver lens options, windy conditions or very hot or humid conditions so the bigger booms and props would help give the extra headroom needed.
     
  7. Paul conto

    Paul conto Member

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    Im doing the 6s vs 4s debate as well. Im on a HEX with QC3328 motors, 14x4.7 Carbon Fiber Blades at 16lbs AUW. Been debating on going 6S, will have to upgrade my ESC's as they are capped at 4S, or switching to OCTO.
     
  8. Dave King

    Dave King Well-Known Member

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    If you don't mind buying big expensive batteries and upgrading your electronics you can get bigtime flight times over 20 minutes. I was seeing 20 minutes at 24.5 pounds.
     
  9. Paul conto

    Paul conto Member

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    WOW, thats awsome. i'm sitting at 8min with 2x 10,000Mha. what is your setup dave
     
  10. Steve Maller

    Steve Maller UAV Grief Counselor

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    Dave King likes this.
  11. Paul conto

    Paul conto Member

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    AWSOME, I need something to read on my trip to Nashville for a shoot. Hopefully will give me ideas for an upgrade or new bird completly.
     

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