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04-08-2012 03:17 PM  9 years ago
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Jgatorman

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Birmingham, AL

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Experts Please Help. Conflicting Information!
Experts please help. I have a CC HV 160 with a scorpion 500kv and a 530kv, 130 tooth main gear and a 13 tooth pinion and my max head speed is not as high as I would like to try. With the 530 I am maxed out at 2025 headspeed and of course much less with the 500kv motor. I have been given conficting information on the subject of increasing head speed while still running the govenor at 95%. First I was told (by a friend) no problem just increase the nominal voltage in the software to up from 3.7 volts per cell(I changed to 4.0v)and your headspeed will increase proportionally and it did in the software and in flight (used tach). However I have also been told that this is not the proper way to increase head speed and the correct way is to increase the pinion size, by tricking the software into believing you are running 4.0v nominally per cell vs 3.7 is actually taking the esc's govenor way over the 100% efficiency mark and causing the govenor not to have any headroom once the voltage drops below 4.0 nominal volts per cell. He stated this would not harm the ESC but it would not function properly either.

Can someone please enlighten me on this subject and the functionality of nominal voltage in the CC software?

The reason for my question is that I have a Ballistic with the helical main gear and pinion size is limited to 12 and 13 tooth. limiting me to 2025 rpm with the 13tooth pinion and the 530kv motor.

Thanks
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04-08-2012 08:07 PM  9 years ago
Jgatorman

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Anybody?????
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04-08-2012 08:35 PM  9 years ago
bkervaski

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(I'm the second friend)

Not really "conflicting" information -- straight from Castle Creations -- the nominal voltage for a lipo is 3.7 per cell, period. Faking it out and setting it to 4.0 makes the numbers in the software look good but doesn't really do anything but help you limit (or eliminate) the governor's effective headroom.

... unless you have some new magic lipos that stay at or above 4.0 volts the entire time ...

You could also just turn the governor off and use your pinion and flat throttle curves to manage your headspeed, Matt Botos is experimenting with this and is having positive results.

Ultimately, you need a different pinion or motor:

http://www.readyheli.com/headspeed-calculator.html

Op is currently running a 130T main and 13T pinion, 12S.
Team Synergy Factory Specialist / Scorpion / Thunder Power / Byron's Fuels
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04-08-2012 08:37 PM  9 years ago
GyroFreak

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While I am not an expert, the 2nd way you stated is true. What cell count are you using ? Since you are pretty much stuck with your current pinion setup, can you go up one cell count ?The case against politicians simply is that when they legislate for all men, they always omit themselves
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04-08-2012 08:41 PM  9 years ago
rapidity

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That's a new one on me. You either have to increase the voltage, 12S to 13S, or increase the KV, buy a new motor, if you want to stick to the helical gearing.
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04-08-2012 08:49 PM  9 years ago
rapidity

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Castle max is 12S, you need a different motor. Cheapest way would be to go back to the original gear and up the pinion.
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04-08-2012 09:22 PM  9 years ago
Jgatorman

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Thanks for the responses. I still would like to know exactly what is occuring when I increase nominal voltage per cell up from 3.7 to 4.0 which provides the desired higher heasdspeed. Does raising the nominal voltage increase the govenor efficiency to the point where the govenor is no longer able to function properly? If not then what is actally occuring? I am trying to understand the relationship in the softare and what is occuring in the esc and govenor when you raise nominal voltage which in turn increases the max head speed while still having the software state 95% efficiency.
I hope I am making my question clear. I have used the method of raised nominal voltage per cell without any noticable repercussions in flight (at least not that I was aware of). I am no longer using that method however I am trying to understand why it seemed to work?
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04-08-2012 09:31 PM  9 years ago
bkervaski

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I still would like to know exactly what is occuring when I increase nominal voltage per cell up from 3.7 to 4.0 which provides the desired higher heasdspeed.
Nothing, just makes the CastleLink desktop software spit out more attractive numbers resulting in you upping your headspeed with a false sense of what your governor headroom is.
Does raising the nominal voltage increase the govenor efficiency to the point where the govenor is no longer able to function properly?
This is going to depend ... based on your numbers, with the 13T at 2050 your ESC has to operate at 97%, which leaves only 3% for the governor to function. With the 12T it's at 105% so the governor would be ineffective.

Castle says 95% is the "sweet spot".

The 14T pinion at 2150 the esc needs to run just under at 94.3%, so if you're desired headspeed was 2150, the 14T would be perfect.

You can learn how all this relates by experimenting with MrMel's headspeed calc and see how they translate to the ESC by loading up CastleLink in demo mode (not connected to your ESC).
Team Synergy Factory Specialist / Scorpion / Thunder Power / Byron's Fuels
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04-08-2012 09:43 PM  9 years ago
Jgatorman

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I am not debating any of your statements Bill I am just curious why it seemed to work. Actually I completely agree with you and and I am flying at 3.7 volts per cell in the software as we have previously discussed.
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04-08-2012 09:45 PM  9 years ago
bkervaski

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I am not debating any of your statements Bill I am just curious why it seemed to work
It's not a debate, it's just math.

It didn't work, you were just running a higher head speed because the software said you were within the limits.

When you correctly adjust for the 3.7v per cell, the software showed you the right percentage, so you lowered your headspeed accordingly.

Keep in mind that lipos don't discharge at a flat voltage, there is a curve (4.2 all the way down to 3.0) and 3.7 is the nominal voltage.

... and you can see within the first 30 or so seconds you're already below 4.0v per cell.
Team Synergy Factory Specialist / Scorpion / Thunder Power / Byron's Fuels
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04-08-2012 10:52 PM  9 years ago
rapidity

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What you'll prob see is the headspeed decay as the batt voltage gets lower. With a proper setup gov the headspeed will be the same throughout the flight as voltage decreases.
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04-09-2012 01:05 AM  9 years ago
Band1086

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What you'll prob see is the headspeed decay as the batt voltage gets lower. With a proper setup gov the headspeed will be the same throughout the flight as voltage decreases.
This is exactly right. With the proper set up you will not see a difference. To make this work right you need to be governed at least 15% below nominal(3.7/cell) battery voltage. What head speed are you looking for?
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04-15-2012 08:09 AM  9 years ago
misskimo

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Voltage through the esc is a constant voltage, the signwave you see is kinda square wave, The top part of the wave thats straight is your throttle %. The lenth is measured in m seconds, the reason its square is fets, They open and close, the longer they stay open the more juice or rpms you get through that phase or that set of windings,
If the throttle % of the wave has lets say a 1 inch measurement for 100% throttle on a graph. And you drop it 25%. Then your max m second measurement will be alittle less than 3/4 of an inch on your graph.
So govern below that 75% will result in heat or very bad efficiency that can damage esc, batteries or motor.

Tony
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04-15-2012 06:13 PM  9 years ago
rexxigpilot

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Voltage through the esc is a constant voltage
Tony, that's not quite accurate. While it's true that the motor speed is controlled by the ESC varying the pulse width to change the average voltage, when the battery voltage drops, so does the peak output voltage from the ESC.

bkervasky already told the OP what he needed to know and the OP stated it in his original post. You are just fooling the software by inputting 4.0V per cell instead of 3.7V. Your headspeed will drop when the battery voltage minus the resistance and other losses are not sufficient to maintain the set headspeed even with the ESC's FET gates open 100% of the time.

BTW, the efficiency is not what is being changed by the governor. The power level or time the FET gates are open is being changed to try and maintain the desired headspeed. It's all about average voltage with respect to time. Once you are at 100% power, you are running at the voltage supplied by the battery less the losses.

Bottom line, leave the setting at 3.7V and keep the throttle percent less than about 90% for consistent headspeed with the CC ESC. If you don't care about a drop in headspeed at the end of your flight or consistent headspeed, then go ahead and exceed 90% throttle or just turn the governor off.
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04-16-2012 11:05 AM  9 years ago
Richardmid1

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Jgatorman,

How are you flying this heli?

Even hard 3D and im guessing its FBL you don't need more than 2000rpm.
60% of the time, it works every time!
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04-17-2012 04:41 AM  9 years ago
steve9534

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yakima, wa.

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Gatorman
I'm not privy to any inside information on the Castle software, but it's possible to make a few presumptions. The speed of the motor and consequently the HS is controlled by the length of the output pulses and their voltage. Longer output pulses and higher voltages naturally correspond to faster motor speeds. The waves that Tony and Rexxi are referring to are (I presume) what they are seeing on the oscilliscope. The height of the wave corresponding to the voltage and the length to the time. What I'm presuming is that the percentages Castle gives you are percentages of the theoretical maximum length of time for the output pulses to give maximum motor speed/power. The percentages are likely on the conservative side and thus you can get numbers greater than 100% depending on the particular setup. What looks to be happening in your particular instance is that the voltage of the output pulses (and consequently the height of the waves that Tony is seeing on his scope) is controlled by the input voltage that you are setting on the controller. This just seems to be an oddity of the Castle programming that what they are calling the input voltage, really affects the output voltage. Raising the input voltage seems to be increasing the output voltage which works as long as the input voltage is above 4.0 volts/cell. Once the battery voltage drops below that, then the output voltage will be whatever the input voltage is minus any losses in the system. I'm guessing that the HS is greater at the beginning of the flight, but tails off after the first minute or so as the battery voltage drops??? I haven't really played too much with the governor function on my Castle controllers and just set the controller to give 100% across the board while flying. I did this after reading some info here that the gov function didn't really work all that well anyway. There is some drop off in power and HS towards the end of the flight, but it's not really a huge problem. Hope this helps. steve.
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04-17-2012 07:50 AM  9 years ago
misskimo

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Yeh, Back years ago i ran my castle at 100%. Back then we had only 25c batteries, and yeh! Its not a bad flight, I also ran 100% on 14s ion back in 2005, Like rex said. Its correct, its not really constant but its trying to be, the average isnt 3.7 though,
but with 65c , Thats a whole different ball of wax, my guess if your flight time is 5 full min, and you use 65 to 75% of your battery, that 3.7 is going to be on the low side,

T
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