Notices
Brushed/Brushless motors, speed controls, gear drives Discuss all aspects of brushless motors, brushed motors, speed controls (ESC's), gear drives and propellers in this forum.

Need some help...Will this work?

Old 10-21-2010, 12:18 PM
  #1  
Senior Member
Thread Starter
My Feedback: (1)
 
CGCINC's Avatar
 
Join Date: Aug 2010
Location: small town, MO
Posts: 236
Likes: 0
Received 0 Likes on 0 Posts
Default Need some help...Will this work?

Just bought this plane from Horizon.... HERE
I also bought the recommended Motor and ESC.....
40 amp brushless ESC
Park 480 Brushless Outrunner Motor
They recommend a Lipo battery from 1320 - 2100mAh and a 3 cell. (I think the 2100 they recommend is a 15c)

I'm wondering if a few of my batteries will work.......

11.1v2200mAh 20c
11.1v3200mAh 20c

I think the bigger mAh's is just longer run time?? yes/no?
Old 10-21-2010, 04:20 PM
  #2  
Senior Member
 
Join Date: Dec 2002
Location: Chattanooga, TN
Posts: 2,198
Likes: 0
Received 0 Likes on 0 Posts
Default RE: Need some help...Will this work?

Sure they will! You are correct that larger capacity (mAh) will get you longer run time. Given their C rating your packs are good for 44Amax. and 64A max. respectively... more than enough for a Park 480 (22A max cont.).
Old 10-21-2010, 06:27 PM
  #3  
Senior Member
Thread Starter
My Feedback: (1)
 
CGCINC's Avatar
 
Join Date: Aug 2010
Location: small town, MO
Posts: 236
Likes: 0
Received 0 Likes on 0 Posts
Default RE: Need some help...Will this work?


ORIGINAL: Dr Kiwi

Sure they will! You are correct that larger capacity (mAh) will get you longer run time. Given their C rating your packs are good for 44Amax. and 64A max. respectively... more than enough for a Park 480 (22A max cont.).
Ok, Thanks, I'm not so good with figuring all that out.
SO.... The motor will only pull what power it needs, right? I guess there's no way I will over power the 40amp ESC then?

I'm trying to figure this out so bare with me...... The Battery is basically like a fuel tank, A storage device?! The motor will draw power from the battery but only up to the Max continuous rating?
If that is correct and the Park 480 is a 22a max cont. motor, why would they recommend a 40amp. ESC? I've noticed the batteries have a max burst C rating.... how does that figure into all this!?!?
AND, one more question, The "C" rating.... Do you matchthe C ratingto the motors Max cont. And is it possible to have too much of a C rating? (like a company recommends a 20c and I happen to have a 30c laying around)

THANKS FOR THEHELP!!!!!
Old 10-26-2010, 10:36 PM
  #4  
Senior Member
 
jdetray's Avatar
 
Join Date: Dec 2004
Location: Napoleon, OH
Posts: 1,617
Likes: 0
Received 0 Likes on 0 Posts
Default RE: Need some help...Will this work?

I'll jump in and try to answer some of your questions. I'm no Dr Kiwi, but I'll do my best.

The amount of current required by a motor is directly related both to the characteristics of the motor itself AND to the size of the prop mounted on it. If you use a prop that is too large, a motor can easily draw enough current to damage itself, your ESC, and even your battery. You are correct to say that the motor will only draw as much current as it needs, but if the prop is too large, the motor will try to draw the current it needs to spin that big prop, even if that current exceeds the max continuous rating of the motor.

It is desireable to use an ESC with a current rating that is greater than you expect your power system will draw. Electronic components are more reliable and last longer when they are not being pushed to their maximum limits. Running components near their limits causes them to run hot, and heat is the great enemy of electronics. This applies to motors and batteries, as well as to ESCs. So it's just smart to give all of your components a safety margin.

The "C" rating of a battery lets you determine the maximum current the battery can safely provide. Multiply the battery's capacity (in Amp-hours) times the "C" rating to get the battery's maximum current.

Example Battery 1:
2200 mAh, 20C

2200 mAh = 2.2 Ah
2.2 x 20 = 44A, the maximum current for this battery

Example Battery 2:
3200 mAh, 20C

3200 mAh = 3.2 Ah
3.2 x 20 = 64A, the maximum current for this battery

Now a practical note: Battery makers often state "C" ratings that are based on ideal conditions that do not necessarily resemble the conditions under which we use the batteries in R/C flying. For that reason, many R/Cers routinely discount "C" ratings to 80% of the manufacturer's stated rating. It's just a prudent thing to do so that you are not over-stressing your batteries.

The "burst" rating of a battery is a way of saying that you can treat the battery as if it has a higher "C" rating if you do so only for short periods, a few seconds at a time.

It is fine to use a battery with a higher "C" rating than your power system needs. Based on the "80% Rule" mentioned above, it's actually a very good idea. The only penalty you pay is that a battery with a higher "C" rating will often weigh a bit more than a similar battery with a lower "C" rating. For most airplanes, the extra weight isn't a concern, but it's something to be aware of.

In summary, don't run your electric flight components near their maximum limits, and don't believe everything the battery makers tell you!

- Jeff
Old 10-26-2010, 10:40 PM
  #5  
Senior Member
Thread Starter
My Feedback: (1)
 
CGCINC's Avatar
 
Join Date: Aug 2010
Location: small town, MO
Posts: 236
Likes: 0
Received 0 Likes on 0 Posts
Default RE: Need some help...Will this work?


ORIGINAL: jdetray

I'll jump in and try to answer some of your questions. I'm no Dr Kiwi, but I'll do my best.

The amount of current required by a motor is directly related both to the characteristics of the motor itself AND to the size of the prop mounted on it. If you use a prop that is too large, a motor can easily draw enough current to damage itself, your ESC, and even your battery. You are correct to say that the motor will only draw as much current as it needs, but if the prop is too large, the motor will try to draw the current it needs to spin that big prop, even if that current exceeds the max continuous rating of the motor.

It is desireable to use an ESC with a current rating that is greater than you expect your power system will draw. Electronic components are more reliable and last longer when they are not being pushed to their maximum limits. Running components near their limits causes them to run hot, and heat is the great enemy of electronics. This applies to motors and batteries, as well as to ESCs. So it's just smart to give all of your components a safety margin.

The "C" rating of a battery lets you determine the maximum current the battery can safely provide. Multiply the battery's capacity (in Amp-hours) times the "C" rating to get the battery's maximum current.

Example Battery 1:
2200 mAh, 20C

2200 mAh = 2.2 Ah
2.2 x 20 = 44A, the maximum current for this battery

Example Battery 2:
3200 mAh, 20C

3200 mAh = 3.2 Ah
3.2 x 20 = 64A, the maximum current for this battery

Now a practical note: Battery makers often state "C" ratings that are based on ideal conditions that do not necessarily resemble the conditions under which we use the batteries in R/C flying. For that reason, many R/Cers routinely discount "C" ratings to 80% of the manufacturer's stated rating. It's just a prudent thing to do so that you are not over-stressing your batteries.

The "burst" rating of a battery is a way of saying that you can treat the battery as if it has a higher "C" rating if you do so only for short periods, a few seconds at a time.

It is fine to use a battery with a higher "C" rating than your power system needs. Based on the "80% Rule" mentioned above, it's actually a very good idea. The only penalty you pay is that a battery with a higher "C" rating will often weigh a bit more than a similar battery with a lower "C" rating. For most airplanes, the extra weight isn't a concern, but it's something to be aware of.

In summary, don't run your electric flight components near their maximum limits, and don't believe everything the battery makers tell you!

- Jeff
Thanks for all that... Helps a lot!
There are so many variables to this stuff....
Old 10-27-2010, 12:50 PM
  #6  
Senior Member
 
Join Date: Dec 2002
Location: Chattanooga, TN
Posts: 2,198
Likes: 0
Received 0 Likes on 0 Posts
Default RE: Need some help...Will this work?


Thanks for all that... Helps a lot!
There are so many variables to this stuff....

As long as you have "n + 1" equations for "n" variables you'll be able to solve the problem! Or just ask Jeff!
Old 10-27-2010, 02:04 PM
  #7  
Senior Member
 
jdetray's Avatar
 
Join Date: Dec 2004
Location: Napoleon, OH
Posts: 1,617
Likes: 0
Received 0 Likes on 0 Posts
Default RE: Need some help...Will this work?

No! Just ask Phill!

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are On


Thread Tools
Search this Thread

Contact Us - Manage Preferences Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service

Copyright © 2024 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.