What Batteries Are You Using?

Discussion in 'CineStar FAQ - Tips and Tricks' started by Josh Lambeth, Sep 27, 2012.

  1. Nick Kolias

    Nick Kolias Moderator
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    Are you guys going to start selling those suckers?
     
  2. Morgan Friedland

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    I purchased 2 11,000mAH batteries about a month ago. It took a while to convert over to EC5 connectors but once I did I started using them and was surprised how short the runs were. My other batteries are all ThunderPower 7700mAH and they seem to be very solid.

    Today I did a test flight. C8/ 3Axis gimbal, Sony 760v and 2 Max Amps 11,000 in parallel. Total flight was just under 23 minutes. Wind was 2-5 Mph and I basically hovered around 6-10 feet but did fly around lightly. Also included two bursts up to 100 feet and back down. The rig didn't seem very balanced and my Yaw kept twitching left and right 5-10 degrees ever 5 or so seconds. I'll have to figure out what the hell was causing that as it usually is rock solid on the yaw. Perhaps my batteries were not centered very well?

    Anyway I did notice the voltage drop from 16.3 to 15.4 almost immediately then slowed down. It stayed at 14.4 for a looooong time. When I was at 14.4 I gassed it pretty hard and saw the voltage drop to 14.0. (This is what scares me the most as you could see a catastrophic voltage drop during a shoot with "Action Packed" consequences.)

    Once it got 14.0v the thing started "falling off a cliff" and was down to 13.8 within a minute. I panicked and landed immediately. With motors off the voltage crept up to 14.4 within a minute or so.

    I will hold on to the batteries. Probably too late to return them anyway. I do like the company though. Since I am in Seattle they ship very quickly and there is also that hand written thank you care I received a few weeks after my order. Who does that these days? I've never received a hand written card from Jeff Bezos ;)

    Maybe their higher C stuff will perform better. They sure do look cool in the jet black wrapper.

    Morgan
     
  3. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    Interesting experiences, Morgan. As you say, perhaps there's more energy available at the lower end of the voltage range, but not for the faint-hearted.

    The yaw twitching doesn't sound like a C of G problem. Did you recal the compass when you were using the dual batteries? Just a chance that the current from the batteries might upset the mag. compass enough. Pure speculation on my part, of course, but that doesn't seem to be a consideration these days. ;)

    Maxamps return policy/money back guarantee is within 30 days, just FYI. They seem pretty good guys with whom to do business, but I'd recommend you call/email Clint before purchasing any of their batteries to make sure it's a good "fit."

    I wonder where LiPo technology will go to next? 100,000 mAH at 100C -- that'll melt the wires for sure.

    I'm just about to take the plunge to cut off all the Deans connectors (one wire at a time!) and switch to EC5.

    Andy.
     
  4. Josh Lambeth

    Josh Lambeth Well-Known Member

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    I got a call from Clint today. I had to go but will be calling him back tomorrow.

    Andy what are you purchasing?

    Josh
     
  5. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    Hey Josh:
    I've sent my two 11000's back to Clint today. I think, just for eval purposes I'm going to try two 10900 100C just to see what flight times I get. That said, do the calculations: 100C where C is 10900. That's a burst discharge rate of 1,090 Amps. It better be brief otherwise something's going to melt -- and probably the ground under the C8!

    I don't want to abuse their return policy, but I would like to see what Maxamps can do for the C8 community -- or anybody else who comes out with good quality, high discharge LiPos that will extend flight times.

    Andy.
     
  6. Josh Lambeth

    Josh Lambeth Well-Known Member

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    Yeah. I am curious to see what the 100C battery does... 1,000+Amp burst sounds scary to me! I do believe the MK BLs can handle 40amps each... which puts the total Max Amps that the MK Distro Board will handle is 320amps correct or am I wrong? I don't think I have ever seen anything remotely close to that number even requested from my copter. Highest I saw was 121A spike... this was when my copter decided to get friendly with a light pole... don't ask. :oops:

    Josh
     
  7. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    100C at a C of 10900 should be scary. I've no idea how to test it without destroying some part of the the Pacific Northwest. I think the proof of these batteries will be in a GPX file. I think the problem is one of sustained versus burst and what "burst" actually means. If we're talking a picosecond or a millisecond that's perhaps plausible...the wires won't know what hit them.

    I won't ask about the light pole if you don't ask about the tree. ;)

    Andy.
     
  8. Josh Lambeth

    Josh Lambeth Well-Known Member

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    How about we both share the stories... and video? Ok ready go!

    Well if your copter goes boom.. with 1000+ I might know about it here in phoenix before you post online... ;)

    Josh
     
  9. Jon Fredericks

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    Andy - any update from MaxAmps on doing custom lipos for us that need 'mo flight time?
     
  10. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    Hi Jon. Yeah...check here.

    Thanks
    Andy.
     
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  11. Jon Fredericks

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    Talked to Mark at Thunderpower today, and told him many of us are looking for a little more beef. They are going to look into it.
    Not sure about other's experience with TP, but we've had good success with their 7800 4s, and also running (2) 5400's in parallel for a good endurance/weight combo.
     
  12. Morgan Friedland

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    I give two thumbs up for TPs. I have some the 7700 4s packs and they are great. Don't go below 14.1 though as they will "fall off the cliff" and drop to 13.0 in about 15 seconds!
     
  13. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    The QC6200's have their own version of The Cliff at around the same voltages. Scary!

    Andy.
     
  14. Nick Kolias

    Nick Kolias Moderator
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    Just to add a little more to the discussion, that cliff effect voltage drop is well known and universal with lithium chemistry batts. If you look at a typical discharge graph of a LiPo it's very apparent. One of the big advantages of LiPo's is the relatively consistent voltage under load but when the batt is close to depleted it's game over quickly thereafter. I do think you need to go a bit below nominal voltage to get the full, useful capacity of a pack. 14.1 or 14.2v is a good, safe cutoff IMO.

    nick
     
  15. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    I agree with you, Nick, although I think I need to do some more timed hover just-out-of-ground-effect flights to see, for a given battery/payload what The Cliff looks like and how much flight time there is between fly mode and plummet mode.

    Wouldn't like to be too far from home and be on the wrong side of The Cliff.

    Not that I have ever done the screaming, fast'n'low, approach and landing, you understand. :rolleyes:
    And who says copters don't have a landing roll....

    Andy.
     
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  16. Nick Kolias

    Nick Kolias Moderator
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    Yeah, for sure. LiPo's are a little like the Big Gaffer- they both have hard outs when they're done! :D :D
     
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  17. Josh Lambeth

    Josh Lambeth Well-Known Member

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    HAHAHA Thats awesome!
     
  18. Sandor Kruise

    Sandor Kruise New Member

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    WARNING about using Maxamps 11000 mah packs..

    we had the same issue here
    these packs work wonderfull on a S800
    however shoving them inside a CS will be dissapointing.
    i mailed Max amps about this and infact they say it is rated 5C only!!
    this is truly a weird answer.
    i asked to ship all our new batteries back , they wont have it.
    so i got about 40 packs brandnew useless unless you have a S800
    here is the email:




    Josch i am suprised to see that if we use 60 amps in the hover
    The voltage drop to below 22 volts.
    This is not ok , I was under the impression that the true 45C was really 45C
    But it looks more like 45Amp.
    Same problem occurs for the 5S batteries.
    I got now also a problem with a customer who replaced his zippys 8000 30C to Maxamp 11000 45C and he has same flight time
    And the weight is the same.
    What is wrong? I can use these batteries only on our DJI S800 since that thing wont use more then 35 -40 amps.
    If this is the best they can do , I have no choice other then returning them at this stage.


    answer :

    Choosing the best battery for a given application is not always easy. Sometimes, much testing has to be done beyond just crunching numbers and hoping it is going to work. I’ll try and explain what I mean by that below.



    We base our packs off of its max burst capability and not the constant C rating many other companies use. The reason for this is that in our main market, RC cars, the burst rating capabilities are far more important than the constant. I know this can be confusing when comparing packs, which is why I always recommend testing a pack first before ordering large quantities. A solid constant amp draw for our 11000Mah packs would be around 5C. This pack is designed for a low continuous amp draw whereas our higher rated packs can handle more power and hold much higher voltage under load.



    The usable Mah of a cell in your application is based on voltage under load. You are not normally going to use the full 11000 or 8000mah of any given pack because of where the voltage cutoff is set. Determining runtime solely by Mah is not a viable option as the capable discharge voltage under load will drastically affect the overall available runtime based on initial voltage drop down to the cutoff voltage. The longer the battery pack can hold voltage before it hits cutoff, the better. This is the key measurement that should be used to determine the best battery pack for your application.
     
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  19. Tristan Twisselman

    Tristan Twisselman Active Member

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    2 TP 6s 6600 25c Batteries are usually cool to warm depending on weather. Flight time with 5 lb camera is about 12 minutes, 14 minutes with 1.5lb camera and if I remember correctly 17 minutes before I added Downlink and camera. As far as changes, I just picked the correct motor kv for 6s and an appropriate esc for my needs when building my CS8. I mount the batteries on the original battery tray side by side. I have thought about trying the 6s7800 but already have 2 sets of the 6600s and dont want to have balance issues with using two different sets batteries.
     
  20. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    I'd like to pull together some entries for the FAQ section that summarize the changes (if any) that one needs to make to convert a C8 from using 4S packs to 6S packs.

    I was wondering whether I might impose on those of you who are flying 6S either to post messages that give a series of bullet item answers to:

    1. What batteries you fly with: e.g. 2 x Thunderpower 6S 6600 25C.
    2. Typical flight times and the cameras (see Twister773's great summary above.
    3. What changes you needed to make (if any) to a standard configuration Cinestar 6 or 8 to fly 6S.

    Again, just brief answers (which may include: "Did not change a thing, just put the batteries on there.")

    If it's easier, click on my name to the left, above the Flight Squad logo, and Start a Conversation and send me a message. I'll then collate the answers and add them to the FAQ.

    Thanks in advance, folks!
    Andy
     

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