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Half stick no more power

Old 11-04-2008, 10:22 PM
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DieHard007
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Default Half stick no more power

I've got a Piper Pawnee 40 running a EXCEED monster power 46 with a 14X10 APCe prop and a turnigy plush 80a ESC with a 5s 4000mah lipo on a Futaba 7C 2.4ghz Tx and a R617FS Rx when i throttle up i can only get half stick and from there on up to WOT there is no more power at all. but if i shut stick all the way off and push to WOT the motor revs up really high but settles back down to half throttle. is this normal.
Old 11-08-2008, 08:19 AM
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Default RE: Half stick no more power

any one have any ideals as to my problem, Thanks
Old 11-09-2008, 04:57 PM
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Default RE: Half stick no more power

Have you tried setting the cell count manually as suggested in the esc instructions?

"We strongly suggest you using manually setting method to set the cells number of your lithium battery pack. Please be careful to use “Auto detect” method."
Old 11-09-2008, 06:35 PM
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Default RE: Half stick no more power

Yes i have checked. it is on 5s detect for sure.
Old 11-09-2008, 08:37 PM
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safeTwire
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Default RE: Half stick no more power

How about the battery being fully charged? I believe they can be charged to a maximum of 4.2v per cell for a total of 21volts for your battery. Just a thought.
Old 11-10-2008, 04:06 PM
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Default RE: Half stick no more power

yes i'm fine there. they all check at 4.2v 21v total. i even tried low,med,high timing also.
Old 11-10-2008, 08:54 PM
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Default RE: Half stick no more power

The 14x8 prop is quite the prop for that motor. At the least, a four stroke 91 is usually an average/minimum choice for that prop. Is it possible that at half throttle stick, your system is delivering all it can to match the motors demand? The bleed off of power after a moment at full throttle makes me wonder if the motor is creating a demand for more current than is steadily available.
A smaller diameter prop with less pitch might do the trick.
How are all the connectors and solder joints?
Old 11-10-2008, 10:31 PM
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Default RE: Half stick no more power

diehard,

is your throttle travel adjustment at 100 % and trim set all the way down ? some times this will affect your throttle.




bassman
Old 11-11-2008, 05:16 PM
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Default RE: Half stick no more power


ORIGINAL: bassmanh

diehard,

is your throttle travel adjustment at 100 % and trim set all the way down ? some times this will affect your throttle.




bassman

you know what i for got about the throttle trim being set all the way down. i need to do that and check it again. thanks for the heads up on that.
Old 11-11-2008, 05:53 PM
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Default RE: Half stick no more power

I don't think your pack is up to it - what is your amp draw?
Old 11-11-2008, 06:21 PM
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Default RE: Half stick no more power

hmmm you would think if the pack was dropping under load that much that the LVC would kick in and shut it down completely.

could be a bad esc or battery pack i suppose. sounds like you will need to do some testing and see what the amps are at try a different escand or battery pack.





bassman
Old 11-11-2008, 06:24 PM
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Default RE: Half stick no more power

Okay, the Nitroplanes Monster Power 46 is about the same motor as an AXi 4120/14. Roughly the same size and Kv rating.

AXi's website recommends a 12x8 prop for their motor with a 5S LiPoly.

I'm thinking the 14x10 is waaaaaaay to big of a prop for that battery pack and motor combo.
Old 11-12-2008, 10:20 PM
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Default RE: Half stick no more power

ya i was going along with what other people where using, the exceed rc monster power 46 is the same spec's as a e-flite power 46. 4 or 5 cell lipos
Old 11-13-2008, 03:31 PM
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Default RE: Half stick no more power

Here is what Motocalc says for an E-flite Power 46: if you are trying to draw 100A and push 1800W into an 800W max motor... you are in deep trouble!

Motor: E-Flite 46BL Outrunner; 670rpm/V; 3.88A no-load; 0.04 Ohms.
Battery: FlightPower 3700 (20C); 5 series x 5 parallel cells; 3700mAh @ 3.7V; 0.0037 Ohms/cell.
Speed Control: Castle Creations Phoenix 80; 0.001 Ohms; High rate.
Drive System: Direct Drive; 14x10 (Pconst=1.17; Tconst=1) direct drive.
Airframe: Anything you want.

Motor Amps = 101.8
Motor Volts = 18.0
Input (W) = 1835.0
Prop RPM = 9345
Thrust (oz) = 182.8
PSpd (mph) = 88.5


Of course, your 5s 5000 pack has no hope of maintaining 18v under load, so your amp draw/watts-in will be a lot lower than this.
Old 11-17-2008, 10:39 PM
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Default RE: Half stick no more power

ok now, i got a watts up watt meter and when i throttle up to wot the motor settles down to a certain rpm at wot and the watt meter shows the battery voltage at 16.90v down from 21.0v. is this normal, it does it on both my lipo batteries. and i still get no throttle response from half stick up to wot then. i only have throttle from idle to half stick but if i close the throttle and then throttle back up i'll have response all the way up to wot, them RPM's settle back down and my voltage is down to 16.80 from 21v. with no throttle response again from half stick to wot.
Old 11-18-2008, 11:38 AM
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Default RE: Half stick no more power

Sounds as though you have two packs... parallel them and see if that changes the equation. If your voltage is dropping that much one pack can can obviously not deliver enough.
Old 11-18-2008, 12:14 PM
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Default RE: Half stick no more power


ORIGINAL: DieHard007

ok now, i got a watts up watt meter and when i throttle up to wot the motor settles down to a certain rpm at wot and the watt meter shows the battery voltage at 16.90v down from 21.0v. is this normal, it does it on both my lipo batteries. and i still get no throttle response from half stick up to wot then. i only have throttle from idle to half stick but if i close the throttle and then throttle back up i'll have response all the way up to wot, them RPM's settle back down and my voltage is down to 16.80 from 21v. with no throttle response again from half stick to wot.
What is the amp draw?
Old 11-18-2008, 08:10 PM
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Default RE: Half stick no more power

it was between 12 to 14 amps
Old 11-19-2008, 01:06 PM
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Default RE: Half stick no more power

OK this is from my watts up watt meter with my Exceed RC monster power 46 (like a e-flite power 46 same specs) a turnigy plush 80a ESC a APC-e 13x8 prop and a EC POWER 18.5v 5s 4000mah lipo at wot the stick with the 13x8 prop now goes up to almost 3/4 throttle. instead of half throttle with the 14x10 prop

7.4Wh

32.09Ap

14.66Vm

473.3Wp

0.456Ah
Old 11-19-2008, 09:16 PM
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Default RE: Half stick no more power

ORIGINAL: DieHard007

OK this is from my watts up watt meter with my Exceed RC monster power 46 (like a e-flite power 46 same specs) a turnigy plush 80a ESC a APC-e 13x8 prop and a EC POWER 18.5v 5s 4000mah lipo at wot the stick with the 13x8 prop now goes up to almost 3/4 throttle. instead of half throttle with the 14x10 prop

7.4Wh

32.09Ap

14.66Vm

473.3Wp

0.456Ah

Your pack is in trouble! At only 14.66v, you are under 3v/cell... disaster! Get a new pack or parallel two packs. Any 5s 4000 pack which is at least 10C should deliver no less than 18V under only 32A load... even if you pushed it all the way to 40A it should still, at least initially, maintain better than 16v.

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