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Old 01-27-2011, 12:07 PM   #1
racquethand
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Default bench test for motor and esc

Hi,

Just bought a rimfire gpmg4620 and a e-flite 40 amp pro bec brushless esc slightly used.

I would like to test them both but I have not bought a battery pack and charger yet.

Can I use a car battery to power up for a test?

Also the wire leads are very short between the motor and esc, I plan on soldering a 6 inch piece of wire between the two, is the length between critical?

Any suggestions would be appreciated.

Bill
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Old 01-27-2011, 02:29 PM   #2
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The car battery should be OK, the ESC is not going to care what the electron source is as long as it in the proper voltage range and can supply the current required.
Do you have a wattmeter? I would use a little caution on how big a prop you use for bench testing and stay toward the smaller end. The possible current draw on that motor may exceed the capacity of the 40 a EFlite if you prop it too high. Looks like the recommended ESC for that motor is a 60 amp.
I have heard that if you need to add length to the system, the best method to do that is to add between the ESC and motor as you are doing, rather than between the battery and ESC. As long as you use a wire of suitable gauge ( as least as big as the wires on the ESC) a 6 inch extension should be fine
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Old 01-27-2011, 06:13 PM   #3
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How are you planning to mount the motor for this test? (probably a bad idea to try to hold it by hand.)

Current - Ventura, HZ SuperCub-Freedom-Swift-AB3, PZ Typhoon, T-28 Trojan, Radian, AeroAce Biplane
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Old 01-28-2011, 12:17 PM   #4
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Default motor and esc

Hi, I mounted the motor and esc on a short piece of 2x4 that has a plywood vertical screwed to the end. After turning the 2.4ghz transmitter on with throttle at idle and having the 12 volts hooked up to the esc input this is what happened:
The blue light came on in the reciever and the esc gave me a long beep then 4 short beeps then 2 more short beeps.
I tried the throttle but the motor just rocked slightly back and forth. Also the servo's connected to the reciever would not work. There are 2 small wires exiting the esc that have been cut off, I can not find them in the e-flite instructions. If I turn the motor shaft by hand it seems to have resistance in places, don't know if this is normal. Should the esc start up and work or do you have to go thru all the programming that is in the instructions? How can I tell if the problem is the motor or the esc?
Thanks, Bill
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Old 01-28-2011, 12:32 PM   #5
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does your ESC look like this


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Old 01-28-2011, 12:35 PM   #6
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if it does, the 2 wires that were cut might be the,
Radio System Power On/Off Switch, you might have to hook those wires together to make it turn on, test with the prop off the motor



E-flite 40-Amp Pro Switch-Mode BEC Brushless ESC
from E-flite
With Switch Mode BEC and advanced programming

The 40-Amp Pro SB Brushless ESC with Switch-Mode BEC, and advanced programming, allows you to operate up to 7 analogue or 6 digital standard-sized servos with the BEC on any recommended input voltage.

Key Features:
Up to 40A continuous current with proper air flow, with 55A burst current (15 seconds)
5V switch-mode BEC circuit capable of 2.5A continuous current on any recommended input voltage
Drive up to 7 analog or 6 digital standard-sized servos with the BEC on any recommended input voltage
3–6S Li-Po, 9- to 18-cell Ni-Cd/Ni-MH input voltage
Finned heat sinks
Programmable motor braking
Safe power-arm mode prevents accidental starts
Programmable low voltage cut-off with settings for 3S Li-Po (9V), 4-cell Li-Po (12V), 5-cell Li-Po (15V), 6-cell Li-Po (18V), or 70% of battery starting voltage
Programmable soft start for helis and airplanes
Auto motor shutdown if signal is lost or there is interference
Programmable timing—5 user-selectable ranges for use with a large e variety of brushless motors
Programmable throttle input range (1.1–1.9ms or 1.2–1.8ms)
Heli mode for starting the motor with a low speed ratio
Utilizes new smaller Mosfets technology to save weight
Radio System Power On/Off Switch
Optional RS232 Serial Link available for programming (EFLARS232)
Pre-wired connectors—E-fliteŽ EC3 on battery input and 3.5mm female

Specification:
Brake: Yes - Programmable
Continuous Maximum Current:40A with reasonable cooling
Input Voltage:10.8V - 22.2V
Input Connector Types:13 AWG with E-flite EC3 Connector
Output Connector Types:13 AWG with 3.5mm Female Gold Bullet Connectors
Momentary Peak Current:55A (15 sec)
Dimensions (WxLxH):68x33x13 mm (2.7x1.3x.5 in)
Weight:62g (2.2 oz)
Wire Gauge:13 AWG

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Old 01-28-2011, 12:41 PM   #7
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also the throttle might be reversed on the Transmitter, try reversing the throttle channel, Hope that helps, Chellie

BTW, you might have gotten someone elses problem ESC, test the motor with a OHM meter, the 3 wires should have the same ohm reading, and none of the 3 motor wires should show a ohm reading to ground/metal of the motor, if that checks out ok, then the problem may be the esc or transmitter being reversed, The turnigy ESC are a very good ESC, its all i use and they work great, i would use a larger that 40 amp ESC on that motor, a 60 would be better to give yourseld a little Cushion,

http://www.hobbyking.com/hobbyking/s...idProduct=2166

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Old 01-28-2011, 12:50 PM   #8
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Default How to Test Brushless Motors

http://www.wattflyer.com/forums/show...rushless+motor

hope that helps, Chellie

I may be getting Older, But I Refuse to grow Up I am Having to much Fun to Grow Up LOL
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Old 01-28-2011, 02:16 PM   #9
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Default motor and esc

After watching a few u-tube videos on esc programing I found I had put the esc plug into the reciever battery pins, instead of putting the esc plug into the throttle pins on my reciever.

When I plugged the esc into the right place my motor and radio all seem to work great. The motor goes from off to full throttle, and the servo's work as they should.

Thanks for all your help, this is all new to me as I am an old 4 stroke guy trying to learn new tricks.

Thanks again, Bill
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Old 01-28-2011, 03:01 PM   #10
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Originally Posted by racquethand View Post
After watching a few u-tube videos on esc programing I found I had put the esc plug into the reciever battery pins, instead of putting the esc plug into the throttle pins on my reciever.

When I plugged the esc into the right place my motor and radio all seem to work great. The motor goes from off to full throttle, and the servo's work as they should.

Thanks for all your help, this is all new to me as I am an old 4 stroke guy trying to learn new tricks.

Thanks again, Bill
Congrats!

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Old 01-29-2011, 01:40 AM   #11
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Originally Posted by racquethand View Post
After watching a few u-tube videos on esc programing I found I had put the esc plug into the reciever battery pins, instead of putting the esc plug into the throttle pins on my reciever.

When I plugged the esc into the right place my motor and radio all seem to work great. The motor goes from off to full throttle, and the servo's work as they should.

Thanks for all your help, this is all new to me as I am an old 4 stroke guy trying to learn new tricks.

Thanks again, Bill
Glad you got it figured out I am a OLD 2 Stroke person I switched to E Power and Love it, I am Never going back to Smelly Slimy 2 strokes Now Days, I smell much better than I did when I flew 2 strokes Take care and Have fun, Chellie

I may be getting Older, But I Refuse to grow Up I am Having to much Fun to Grow Up LOL
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Old 01-29-2011, 04:10 PM   #12
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I'm an old diesel guy! If you want to test other motors in the future you could use something like this: http://www.rcgroups.com/forums/showt...t=thrust+stand
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Old 01-29-2011, 10:50 PM   #13
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Originally Posted by Dr Kiwi View Post
I'm an old diesel guy! If you want to test other motors in the future you could use something like this: http://www.rcgroups.com/forums/showt...t=thrust+stand
Oh No, Not Diesel I converted a 2 stroke to a diesel,(Davis Diesel) talk about smelling Funny after flying, the burnt diesel smell would stink up my car and me Big Time, I got away from diesel, because i was starting to Really Smell Funny LOL, Take care and Have fun, Chellie

I may be getting Older, But I Refuse to grow Up I am Having to much Fun to Grow Up LOL
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Old 01-30-2011, 02:20 AM   #14
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"I'm an old 4 stroke guy"..."I'm a two stroke guy"...


..Why does that sound so dirty?!?!

"Give a man a plane and he'll fly for a day.
Teach a man to build a plane and he'll fly for a lifetime"
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Old 01-30-2011, 02:29 AM   #15
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Originally Posted by FlyWheel View Post
"I'm an old 4 stroke guy"..."I'm a two stroke guy"...


..Why does that sound so dirty?!?!
LOL
Because after putting your glow powered model back in the car, and getting oil all over your new pants, you WERE dirty!
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Old 01-30-2011, 12:33 PM   #16
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Default removing the bec wire to the reiever

This is the old four stroker with another question .

I was told to remove the connection between the esc and the reciever on my e-flite 40 esc. And to use a battery pack plugged into the reciever to power the servo's and reciever. The reason to do this was that the bec circuit could overheat and fail because of servo draw causing complete loss of control to the plane. This way if there was a esc failure you could at least glide the plane down to land it. I would like to know how many of you have seen this happen in the past ? Also I am considering buying a lipo 2200 4s battery , I am thinking the higher voltage will draw less amps thru the esc. what is a good charging current for this pack, and how long does it take to recharge. I will be using a imax b6 to charge.2 The next plane I am interested in building is the stevens groove 480. Can this plane be safely flown in a ball park ? Thanks, Bill
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Old 01-30-2011, 06:47 PM   #17
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Originally Posted by racquethand View Post
This is the old four stroker with another question .

I was told to remove the connection between the esc and the reciever on my e-flite 40 esc. And to use a battery pack plugged into the reciever to power the servo's and reciever. The reason to do this was that the bec circuit could overheat and fail because of servo draw causing complete loss of control to the plane. This way if there was a esc failure you could at least glide the plane down to land it. I would like to know how many of you have seen this happen in the past ? Also I am considering buying a lipo 2200 4s battery , I am thinking the higher voltage will draw less amps thru the esc. what is a good charging current for this pack, and how long does it take to recharge. I will be using a imax b6 to charge.2 The next plane I am interested in building is the stevens groove 480. Can this plane be safely flown in a ball park ? Thanks, Bill
It would be a good idea if you don't have one to beg, borrow, or buy one of those wattmeters such as the Astroflight Whattmeters, and actually measure the watts, volts and current going into your motor.

These electric power systems are different that the glow engines. Going from three cells to four cells on your battery with the same propeller can cause the power input to your motor to nearly double. And that could let the magic smoke out of your motor.

www.motocalc.com predicts that your motor will burn up in short order on four cells, and a 9X4.5 prop.
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Old 01-31-2011, 12:13 PM   #18
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Default bench test

Hi Kyle,

The previous owner had this set up in a ugly stick, he tested current draw with a 10x7 prop and read 32 amps.

I have been reading the electrifly power recommendations for a outrunner brushless motor and they stated the following: typically picking a higher voltage battery pack will result in a power system that consumes less current. You can substitute voltage in picking a power set up and the higher the voltage the lower the current draw. Thats why I thought it would be better for me to use a 4 sell lipo instead of a 3 sell.

I am new to all this and hope I can learn as much as possible before spring.

Thanks for your help, Bill
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Old 01-31-2011, 05:28 PM   #19
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Originally Posted by racquethand View Post
Hi Kyle,

The previous owner had this set up in a ugly stick, he tested current draw with a 10x7 prop and read 32 amps.

I have been reading the electrifly power recommendations for a outrunner brushless motor and they stated the following: typically picking a higher voltage battery pack will result in a power system that consumes less current. You can substitute voltage in picking a power set up and the higher the voltage the lower the current draw. Thats why I thought it would be better for me to use a 4 sell lipo instead of a 3 sell.

I am new to all this and hope I can learn as much as possible before spring.

Thanks for your help, Bill
Yup, that is true, for a given amount of wattage (horsepower) a higher voltage allows the use of lower current. The formula is watts equals volts times amps. And horsepower equals watts divided by 746, so 200 watts/746 is about 1/4 hp.

BUT, that is assuming you are buying a motor that is designed for the higher voltage. Or, putting on a smaller propeller that allows the motor to spin faster without exceeding the motors maximum current rating. Problem is, with a smaller propeller turning at much higher RPM, you could actually wind up with lower performance on a slow flying model. Big slow turning props on slow flying models just seems to work better.

Going from 3 cells to 4 cells on the same motor and same propeller can result in pulling nearly double the wattage out of your battery pack. And if the battery pack/ESC/motor can't handle it, you can damage your battery pack/ESC/motor.

One of those computer programs such as www.motocalc.com allows you to put in your motor, a propeller (or a range of propellers), an ESC and battery (Or a range of batteries from 2 cells to 4 cells or what ever) and give a prediction of the motor RPM, current, voltage, watts, and a lot of other stuff.)

And this program will warn you if you're getting close to burning anything up, even before you buy any of the power system parts. Its free for 30 days, and $39 after that. Playing with a lot of the numbers in this program will show you a LOT of stuff, at little cost. Then, when you find a power system that looks good on your model, you can buy what's needed for your setup. Or, select the proper propeller for your existing setup, and be fairly close. That is, unless the manufacturer of your motor is way the heck off in their motor specs. Not to uncommon for those cheap China motors.
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