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Old Jan 23, 2013, 11:59 AM
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There is a margin particularly at the start but a significant one.
if the 65c batt holds .7 more vdc under load then that would equate to 1500+ more rpm at the start of the run............yes! it is significant, how the run ends is significant also. the 65c pack will be ending with a voltage of 3.4-3.5vdc per cell and the 30c pack will be down to 3-3.2 volt per cell.....thats a big diff
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Old Jan 23, 2013, 12:58 PM
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Jcdfrd: but as you know volt/amp at top end isn't a linear rpm result. So the spread starts to diminish. You can calc the rpm with KV and Volts but it seldom gets to that rpm. So that .7V, while there becomes less significant in end result. If you must have it cause you are looking for speed records or max pull out, sure you do everything you can to be in your favour. However, the average flier won't see it up front, but will on the tail end and life cycle.

And I suspect the margin aren't high enough to really note if done with like brands and types between C ratings. If you want to get accurate numbers someone would have to get all the same brand e.g. current Nano, in its various C ratings run in the same conditions.

And as I said at the beginning of the conversation there is a slight increase but when you watch the end results on the same model same drive train, the C rating isn't making the difference up front. On the tail end of the run it does. That's the advice to pilots question, do I "need" to get a 65C battery or what will do. The answer how do you intend to fly and what can you afford? As long as its a light high C with known decent performance, it is a better investment. But if you are just interested in mixed flying and not looking for hard ballistic or 3D, then 40C will do.
Just be conscious of the weight because the tail end of the battery run of a high C battery can be undone by its extra weight.

So as said from the start, its there but its not some huge leap and it can change from brand to brand and batch to batch. Thus why you can see good numbers from a quality lower C battery performing as well as a low quality higher C battery. The C ratings are a marketing cheats where they use as much wiggle room as they can from the ingredient of the batch formula. Thats where its not just a IR number because theres ways to cheat that but still be poor at delivering energy.
So you are better off finding a brand that is doing well, than just think High C rating must do better. That's why I created that battery list with everyones videos with all their batteries. For the first minutes or so they all start out looking the same. So if a new pilot isn't looking to 3D and doesn't want to spend top $ he can get a shorter window of similar performance but will experience drop off sooner.
But they do need to understand the drop off, when it happens and when they keep pushing the chemistry of their battery of a lower C, how its doing so by pushing into the peak rating and potentially boiling the battery.... and not always just boiling since there are other ways to break down a compound other than heat.

A 25C is going to see a measure of difference to a 65C. But 30C to a 45C, or 45C to a 65C between brands it get less discernible.
And since we typically keep recommending 40C and up, the spread is less significant when you are discussing performance before the capacity drop off.

In parallel we're also trying to explain why those who still try to use 25C with demanding EDFs can't just say it flew just as good when considering the life cycle of the battery. [Whiskey] showed the new Nano 25C to perform very well, but I suspect it will be short lived unless Turnigy came up with something different in the new Nano formula, which again can be as significant as a slightly higher C rating.

Sorry if this prattles on cause I can't see everything I've posted till I've posted it. Got to get the phone replaced.
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Old Jan 23, 2013, 01:18 PM
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As you folks know I have been looking for a power source to use my servo tester when assembling the 35. It was suggested to me just to use a BEC to power the tester. I solderd one today on to the wiring that will be going into my Raptor. I think this set up will work ok with the tester wont it?
VID00452 (1 min 16 sec)
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Old Jan 23, 2013, 03:00 PM
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Jcdfrd: but as you know volt/amp at top end isn't linear. So the spread starts to deminish.
To I don't think the margin is that high enough to note. You can have as much variation with like batteries or brand as you would between C ratings.

If you want to get accurate numbers someone would have to get all the same brand in its various C ratings run in the same conditions.

And as I said at the beginning of the conversation there is a slight increase but when you watch the end results on the same model same drive train, the C rating isn't making the difference up front. On the tail end of the run it does.

But that tail end advantage can also be deminished by the added weight of the heavier C rated battery and can have an even greater variation with brand and batches.

So as said from the start, its there but its not some huge leap.
I would add it why you see good numbers from a good quality lower C battery vs a low quality higher C battery. The C ratings are a marketing cheat so you are better off finding a brand that is doing well than just think its a High C rating so it must do better.
That's why I created that battery list with everyones videos with all their batteries. For the first minutes or so they all start out looking the same. So if a new pilot isn't looking to 3D and doesn't want to spend top $ he can get a shorter window of similar performance but will experience drop off sooner.

Thing is as I've said I agree to a point. A 25C is going to see a measure of difference to a 65C. But 30C to a 45C, or 45C to a 65C between brands it get less discernable.
And since we typically keep recommending 40C and up, the spread is less significant when you are discussing performance before the capacity drop off.
In parallel we're also trying to explain why those who still try to use 25C with EDFs can't just say it flew just as good when considering the life cycle of the battery. NC showed the new Nano 25C do very well, but I suspect it will be short lived unless they come up with sometthing different in the new formula, which again can be as significant as a slightly higher C rating.
Sorry if this prattles on cause I can't see everything I've posted till I've posted it. Got to get the phone replaced.
well one thing that is for sure there are so many variables to the equation that I can see both opinions being correct depending on setup.....this is the problem
I have an example of where going from 45c 4500 nano's 12s in our race Habu32 produced 170+mph speed runs then upgrading to 65c 3300 nano's 12s produced a considerable faster Habu32 with speeds in excess of 200mph. the batteries packs weighed the same the difference was 5k more rpm. here is what a 200mph Habu32 on 65c packs looks like....enjoy!
Team Habu Burners 65C Speed Run #2 (3 min 36 sec)
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Old Jan 23, 2013, 04:49 PM
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well one thing that is for sure there are so many variables to the equation that I can see both opinions being correct depending on setup.....this is the problem
I have an example of where going from 45c 4500 nano's 12s in our race Habu32 produced 170+mph speed runs then upgrading to 65c 3300 nano's 12s produced a considerable faster Habu32 with speeds in excess of 200mph. the batteries packs weighed the same the difference was 5k more rpm. here is what a 200mph Habu32 on 65c packs looks like....enjoy!
Ok. J. There is an accumulated advantage making it more obvious as your cell count goes up. And then flying 1minute balls to the wall on a well tuned machine, where its most visible for a Higher C rated batts that has an even wider burst gap....and assuming these are the same battery formulas, an approximate 30mph increase is impressive.
What battery packs were they, the 45C to the 65C on which fan? Not that I double you and I assume the 170+ and the 200 was read from the same vario or gun to note such a spread.
May be some where in there, there may be factors why it translates less obviously to a simple dirty setup like the Su trying to fly 3D and not just straight speed passes.
Was that with the CS cut down to 80? or Tams?
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Old Jan 23, 2013, 05:40 PM
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yes max that was the point I was trying to make, diff setups will do diff things, a finely tuned setup can take advantage of more available power from a batt whereas a lesser quality or mismatched setup will show little to no gain and possibly even the smoke hehe!
the batteries are nano techs the edf unit is a TJ80 12s PnP wemo pro cut down to 80mm
the speeds are dopplered from the vid and really the important part is 5k more rpm whether or not that translates into mph is upto the airframe and pilot but that is a huge diff from only changing a battery.
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Old Jan 23, 2013, 06:28 PM
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K fair enough. You wouldn't happen to collect voltage data with those as well?
For you to get an extra 5K rpm even with a 12S that's an even wider voltage spread since your kv would be lower to push 12S thru it.
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Old Jan 23, 2013, 06:37 PM
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This is a interesting post regarding batteries and performance. Although I don't know anything about EDFs, I do know quadcopters. My f450 naza showed GREAT improvement when I changed from a 3cell lipo to a 4cell nano. It flew faster and preformed markedly better.
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Old Jan 23, 2013, 06:40 PM
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hehe, that is Voltage and a 33% rise in it... which then also causes higher current, so total Power goes up a LOT.
Not quite the same as the same battery cells/voltage... but different C's and construction etc. Which are not changes in the order of 33% volts increase, or 50% Power resultant increase.
More like 3% to 10% max range.
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Old Jan 23, 2013, 06:45 PM
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This is a interesting post regarding batteries and performance. Although I don't know anything about EDFs, I do know quadcopters. My f450 naza showed GREAT improvement when I changed from a 3cell lipo to a 4cell nano. It flew faster and preformed markedly better.
3s to 4s is a whole different topic of what's being discussed. When you increase the voltage of the battery being used 3s to 4s of similar mah regardless of C rating or brand you will see a big performance boost when using a high cell count.
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Old Jan 23, 2013, 07:06 PM
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Ya Gold. That approach isn't always available as an option because with EDF we're already running above the motors limit in many cases and thus can't just add another 4V without risking cooking some motors.

It always been understood that higher C ratings aren't generally enough to push most setups over the burn line. But that just depends on how close you already are.

I've never heard if anyone has tried the stock setup on 7S to know how far above its 60amp max it can go.
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Old Jan 23, 2013, 07:11 PM
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I would use 7S or 8S on lower KV to get more efficiency.
But there are no motors for CS10/12 to run that.... in the required power range (1200W area)
My 7S 5000 is the same weight as the 6S 5800..... and the 90A ESC's can do 7S (but the Amps won't go up anyway... they will go DOWN).... so it just needs a 1800kv 28mm motor (pair).....

Oh!! I think Leopard actually do have some sub 2000kv 28mmx60mm can motors..... (need the 1840kv area)

http://www.leopardhobby.com/proviewe...=1&gid=71&pt=3
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Old Jan 23, 2013, 07:30 PM
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3s to 4s is a whole different topic of what's being discussed. When you increase the voltage of the battery being used 3s to 4s of similar mah regardless of C rating or brand you will see a big performance boost when using a high cell count.
Sorry please excuse my ignorance! I guess I was just trying to contribute. I will keep my mouth shut! I will learn more that way. LOL
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Old Jan 23, 2013, 07:47 PM
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Hehe Goldsworthy....
What you can do is...... whenever you THINK you know something, say "I think....", "I heard...." , "I believe...."etc.
As an 'out' for the fact that you MIGHT be incorrect. And if you are right, it doesn't alter anything.
And then even if proven wrong... just say "Oh ok, my mistake, thanks for that"... rather than take anything ever as a personal attack (even if it was! LOL).... because it is likely you DID learn something, thus fine to thank them for that anyway. hehe

There are only 1,234,456 things to know about electric model aircraft, so expect to NOT know quite a LOT of things! hehe
PS: Nothing in your post was actually wrong... just an incorrect analogy or comparison.
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Old Jan 23, 2013, 07:53 PM
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Thanks! I wish you folks lived closer to Tucson Arizona I have a large liquor cabinet plum full of 1st quality expensive booze I would be glad to share!
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