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how to choose ESC?

Old 08-17-2011, 06:06 AM
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Q8Helper
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Default how to choose ESC?

hi

im new with electric rc airplanes i dont know how to choose the best ESC

now i have motor A4120/7 kv610 and 3 battries all of them 3s two of them 3300 mah 11.1v one 5000 mah (i dont know what all this numbers means)

as i heared before with this motor i need 4-6s lipo .. so i wil connect 2 battries to be total 6s

now in this case what will be best ESC how to choose?

thanks
Old 08-17-2011, 06:31 AM
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exeter_acres
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Default RE: how to choose ESC?

I'm sure there is some whacky formula... but if this is the motor

http://www.bphobbies.com/view.asp?id...1&pid=B2171400

it says it is rated for a max of 55A... so me? I'd get a quality 60A ESC that can handle the cells that you want to use.
Old 08-17-2011, 06:41 AM
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BuschBarber
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Default RE: how to choose ESC?


ORIGINAL: Q8Helper

hi

im new with electric rc airplanes i dont know how to choose the best ESC

now i have motor A4120/7 kv610 and 3 battries all of them 3s two of them 3300 mah 11.1v one 5000 mah (i dont know what all this numbers means)

as i heared before with this motor i need 4-6s lipo .. so i wil connect 2 battries to be total 6s

now in this case what will be best ESC how to choose?

thanks
The ESC you choose depends upon the Voltage you use and the amount of Current your motor draws. Both Motor and ESC are rated for Current and Voltage. Fully charged LiPos are 4.2v per cell, so 6S would be 25.2v. The amount of Current you need depends upon what Diameter and Pitch Prop you use. The larger the Prop, the more Current you will need.

Your batteries are rated as to how many C they can handle during Discharge. One C represents the rated capacity of the battery. In your case, a 5000mah (5a) battery equals one C. If your batteries are rated for 30C Discharge, then your batteries can handle a Discharge Rate of 150a. There are usually Continuous and Burst ratings marked on the battery or in it's specs.

A good starting point is either a Manufacturer's recommendation or a review by someone who has flown the aircraft in question and has some specs that worked for them. Having a Wattmeter will allow you to measure the Current, Voltage, and Power, while the engine is running, to ensure that you do not exceed the specs. If you find that the Current is too high, you can reduce the Size or Pitch of the prop. If the Current is too low, you can increase the Size or Pitch of prop. If you find that at Max Current, you do not have enough Thrust, then you need to Increase the Voltage and/or use a larger ESC or Motor.

The Castle Creations ICE series of ESC's have a Data Logging feature so you can connect it up to a PC or Laptop and look at a number of different parameters over the previous 20min of runtime. Since most Wattmeters can only handle 70-100a, I have had to rely on the data from the ICE ESV for my larger 50v motors that draw in excess of 140a. I burned up my Wattmeter by not paying attention to this.

Regarding LiPo voltage, Nominal Voltage is 3.7v per cell, so a 3cell LiPo starts at 11.1v but charges to 12.6v. Usually you do not want to Discharge LiPos to more than 3.3v per cell. The ESC you choose is most likely Programmable and the Cuttoff Voltage can be set to what you want or be Automatic.

Many ESC's have a Voltage Regulator, called a Battery Eliminator Circuit (BEC), that splits off one voltage to the Receiver and another voltage to the Motor. If you use high end Digital servos, that draw a lot of Current, sometimes you need to either use a separate Receiver battery or an External BEC that is wired into the Motor Battery. It all depends upon your aircraft. Many ESC's have BEC's that can only handle 5a or less of Current.
Old 08-17-2011, 08:20 AM
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JIMF14D
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Default RE: how to choose ESC?

Well you can pick a 60 amp ESC to match the motor but finding out what really matches the plane and the batteries you have takes a little more work.

If you want to get a real feel for this stuff download the program called Motocalc from the net. You put in your planes details (wing span, wing time, model type, weight etc) and then you can put in the motor and battery configuration want to use along with a prop size. Run the program and it will give you estimates of motor current, run time, speed and recomendations.

If you have a plane but no motor ideas, just plug in the info and MotoCalc will give you a list of dozens of recommended motor and prop combos.

Free for 30 days, after that you can pay $39 and register it to use it forever.

If you are serious try it out. You will learn alot and probably pay for it quickly by not burning up motors, esc, batteries and in some cases Ihave seen, actual planes inflight!

Have fun.
Jim D.
Old 08-17-2011, 09:05 AM
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rmh
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Default RE: how to choose ESC?


ORIGINAL: Q8Helper

hi

im new with electric rc airplanes i dont know how to choose the best ESC

now i have motor A4120/7 kv610 and 3 battries all of them 3s two of them 3300 mah 11.1v one 5000 mah (i dont know what all this numbers means)

as i heared before with this motor i need 4-6s lipo .. so i wil connect 2 battries to be total 6s

now in this case what will be best ESC how to choose?

thanks
STOP- and do some studying before you go further - The size of power supply(batts and motor) can be deadly if you screwup

as a basic approach NEVER put a prop on the motor till the plane is firmly anchored and you are behind the prop arc - these setups will reach full power in under one second.
batt sizes and prop loads mean everything here - read up before you screw up. There ain't no instant formula.
Old 08-17-2011, 03:58 PM
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Default RE: how to choose ESC?


ORIGINAL: exeter_acres

I'm sure there is some whacky formula... but if this is the motor

http://www.bphobbies.com/view.asp?id...1&pid=B2171400

it says it is rated for a max of 55A... so me? I'd get a quality 60A ESC that can handle the cells that you want to use.

If Tthe above is the motor it suggests (Use this motor with 4-6 cell Li-Poly packs and 11-13 inch props on planes up to 8 lbs flying weight. We suggest propping for around 800 watts continuous. Manufacturer suggests a 12 x 8 prop on 5 cells or 13 x 11 on 4 cells. )

Old 08-17-2011, 07:41 PM
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Default RE: how to choose ESC?

Jeff Here, It all depends on what your flying. Weight, prop size. Just need a little more info. I will help the best I can. I work and I am not perfect by any means. BUT all I fly is electric. I have a FRENZY, Lancier, Seawind, Electrastar, and well you get the idea. I have a few.
emails [email protected] I check it every day. But sometimes only once a day. Don't have a Smart Phone yet.
May All Your Landings Be Smoooooth!!
Old 08-18-2011, 04:41 AM
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Q8Helper
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Default RE: how to choose ESC?

thanks all for your great support

Jeff, wellmy plane isExtra 330L EPhttp://www.channel4models.com/catego...l-ep-artf.html





i just got ESC platinum pro 120A HV-OPTO new..

but can it be used normal with my moto A4120/7 kv610 with the 3s batteries?

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