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Old Apr 16, 2003, 12:15 PM
Ohe
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Belgium
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Mega 16/15/2 & controllers

Hi,

I just buy a Mega 16/15/2, plan to use it in a Wemotec 480 on 8 cells maybe 10…

What’s the best choice
-MGM compro TMM 40 3ph
-JETI JES 40-3p

And is it responsible to use the BEC?

Thanks
Olivier
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Old Apr 16, 2003, 01:29 PM
EDF Head
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Stavanger, Norway
Joined Feb 2000
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On 8cells the 40A ESC's will work but on 10cells the motor will most likely fry.
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Old Apr 16, 2003, 02:28 PM
Ohe
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Belgium
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Ok, I stay at 8
40A is good, but now, wich one the JETI or the MGM?
and Bec or not Bec?
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Old Apr 16, 2003, 02:58 PM
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Oliver

I'd go with the Jeti they are a quality product. BEC on 8 cells should be fine.

Bob
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Old Apr 16, 2003, 06:40 PM
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Oliver

I have two maga 16/15/2 's and fly them regularly on 10 cells (not zapped) and have no problems. Static tests indicate a max of 40A but these only done for a short time. In the air (Dynamic) the motor is pulling between 31 and 33 A. The controller I use is the Hacker Master Controller 40-3P. This controller allows you to run at the right frequency and Timing to get the best performance etc.

Hope that is of some help

Graham Chilvers (GCMDesigns) www.gcmdesigns.co.uk
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Old Apr 17, 2003, 04:56 AM
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Stavanger, Norway
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I dont have first hand data but a friend tested the 16/15/2 on 8x2600's and got 36A readings. Using smaller cells will yield less voltage though so those figures would be less. However using 10cells is borderline, spend a little more to be safe Just advice based on my gut feeling

Haldor
www.halair.com
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Old Apr 17, 2003, 10:02 AM
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istanbul, TURKEY
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Hi,

With 8 cells, at start-up draw 42 amps and drop to 38 for 1,5 minutes. If you want to use 10 cells, need to go with a 55+ ESC. At start-up draw 58 amps and stay 53 for nearly 1 minute.

I'm using 8 & 10 cells of CP-1700 standard cells with this power setup.

For 8 cells, my ESC is a Jeti-40 and I recommend making good cooling cause ESC become hot. I attached it just behind the motor for cooling; with 10 cells, I'm using Jeti-70 and work without any problem. Both of my ESC's have BEC.

Bora
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Old Apr 17, 2003, 02:56 PM
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Bora bora

What fan are you using with 8 cells 1300,1700 and 2400 I only see 30A and 7.5volts static from mega 16/15/2. This would be like flying at half throttle. with 10 cells I see 40A at first but this quickly drops to 35A.

In the air the motor will run at less current so it is quite safe to use 10 cells.

I will add that the motor gets just as hot doing static tests with 8 cells as it does with 10!!

I have static tested with 10 zapped RC4/5SC cells:-42A 9.7Volts 400W

This was done for 30 seconds the motor was warm. 110' would cause the magnets to fail.

I have had two 16/15/2 motors for 8 months now using 10 cells in the air and they are both still fine and wearing the mini impeller blades down est 40000 rpm.

Graham
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Old Apr 17, 2003, 05:37 PM
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Graham, it's wemotec minifan + standard inlet ring setup. Motor runs at open air, newer tested in a duct.

I tried a new tests tonight with 8 cells of CP-1700 pack with my 40-3P ESC and at start-up every time motor draw 41 amps then droped to 38 amps range in couple of seconds. After 70 - 73 minutes later reached to 35 amps at 8.1 volts.

With my 10 cells test in the past, at 2/3 throttle I reached 40+ and never gone further, immediately swaped to Jeti 70.

40 Amps ESC will be O.K. only for Mega 16/15/3 motors + 10 cells pack. Motor starts with 35-36 amps and drop to 30 amps.

Bora
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Old Apr 17, 2003, 05:50 PM
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Borabora

Well thats interesting the only difference is my fan is in the duct of a F-15 or F-18 and I use the hacker master controller.
The jeti 40A controllers work but don't produce as much power because you can not programme them to 16KHZ or change the Timing!!

My measurements are collected by Watt metermeasuring AMPS Volts Watts.

I have never seen more than 30A with 8 cells on the 16/15/2 motors I have.

8 cells will fly my models but 10 cells is better

Graham
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Old Apr 17, 2003, 05:56 PM
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Reston, VA
Joined Dec 1999
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Graham:
I was very curious about you running the 16/15/2 on 10 cells. It seems it would be too much. Your voltage(9.7) on 10 cells (cp1700's) at 42 amps is very low. I get 10.7 volts on my packs at 50+amps hot off the charger. On 8 cells you are getting 7.5 volts under only a 30 amp load, that is less than one volt per cell under a relatively light load. It takes over 500 watts to turn a minifan 40,000 rpm
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Old Apr 17, 2003, 06:02 PM
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Graham,

I guess we are using same controller. Jeti model, Hacker 6-12 NC Master 40-3P controller in black shrink suit I use an Astro wattmeter, I guess you use also the same Well, I changed the timing for Mega's when I got the ESC but really don't remember the exact KHZ

I just want to add one more thing, at start-up with 8 cells, 40-3P controller I see 41-42 apms, but when I use Jeti Advance 70-3P controller, motor starts with 38 apms. Well, I never understand this difference really

Bora
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Old Apr 17, 2003, 06:21 PM
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Mark

Firstly I do not claim to get 40,000rpm on 8 cells.

I think 10.7V is very high for std 10 cells are you sure these are not zapped!

To get over 1V per cell under load is not my experience have you calibrated your meter?

I am flying 10 cells all the time with the mega 16/15/2 and it does not burn out. So I dont have excessive Current in the air.

Taking measurements straight of the charger will always give you a high current because it is a static test. I really feel that static tests should only be done once if at all. As I think this is the way any motor will be damaged.

Once the model is in the air the load will be reduced by the fact the fan does not have to accellerate through the duct.

Graham
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Old Apr 17, 2003, 07:29 PM
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Graham

I am not trying to hold you to that 40,000 rpm although I thought you were estimating what you might be getting on ten cells not eight. I was just trying to put the power required in perspective

also since you have been flying this setup without problems it must work. I am just trying to figure out why there are these pretty big differences in amps and volts under load

Yes my cells are zapped but in your test:
"I have static tested with 10 zapped RC4/5SC cells:-42A 9.7Volts 400W" your cells are zapped too so the comparison is fair and my load is higher

If you look at published discharge curves for cp1700's and cp or rc2400's I think you will find that that easily hold over 1 volt per cell through most of the discharge under 30-40 amp loads.

I think Herb has measured in flight amp loads and found that fans do not unload as much as props and amp draw is only slightly lower in flight

the only other thing I can think of is that you have programed your speed control and maybe this has really improved the performance of this motor. I am just trying to learn from this. This motor cost a lot less than my Hackers an Kontronik's and if it performs this good I will try oneI have static tested with 10 zapped RC4/5SC cells:-42A 9.7Volts 400W
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Last edited by Mark; Apr 17, 2003 at 07:45 PM.
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Old Apr 17, 2003, 07:48 PM
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Mark

I will try some more tests at various throttle settings with the standard jeti 40A controller and master controller.

I can compare two mega 16/15/2 and a hacker B40 7L. The hacker is a very good motor caperble of 600-700W on 12-14 cells but weighs more than the Mega.

I think the Volts are alot higher with the mega at lower throttle's. I have noticed this before. It may have something to do with load/ controller set up?

Graham
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