R/C Tech Forums

Go Back   R/C Tech Forums > General Forums > Electric On-Road

Like Tree12Likes
Reply
 
Thread Tools Search this Thread
Old 04-26-2017, 07:29 AM   #31
Tech Elite
 
jlfx car audio's Avatar
 
Join Date: Nov 2007
Location: jackson,tn
Posts: 3,354
Trader Rating: 36 (100%+)
Default

Quote:
Originally Posted by YoDog View Post
There is really no way of relating timing/gearing to unloaded amp draw.
The only way to get any real correlation is through good'ol trial and error on the track or test pulls on a motor/chassis dyno. Some motors may draw very little current unloaded but draw way too much current with a given timing/gearing combination while others may draw more unloaded amps while being more efficient under load. You have to find the so called "sweet spot" where efficiency and power output become harmonious. The only way to do this effectively is under load. All motors will react differently, even of the same brand or model. The same analogy relates to speakers (electro-mechanical piston). You can take 2 of the same 8ohm (windings) speakers of the same size and depending on enclosure and suspension (load over RPM), they will have completely different impedance (dyno) curves throughout the same frequency/RPM range. But if you connect an ohm meter to their leads they will show the same relative impedance in a static, unloaded state. These are both electro-mechanical motors and have their own performance characteristics under load. One may be more efficient at 45Hz (rpm) and the other more efficient at 38Hz. The load will reveal these efficiencies. Without the load, you are only looking at the static efficiency of the motor vs timing.

That having been said, I'm still using the 6A method and I hate myself. Gotta get that damn dyno finished!
You are speaking my language! But I have never once thought about that, and your spot on. Any all change to a speaker box or even the interior of the car will affect impedance rise, thus affecting output at some point in its frequency response.
jlfx car audio is offline   Reply With Quote
Old 04-27-2017, 06:26 PM   #32
Tech Regular
 
roosterreagan's Avatar
 
Join Date: Apr 2016
Location: music city
Posts: 280
Trader Rating: 16 (100%+)
Default

Quote:
Originally Posted by YoDog View Post
There is really no way of relating timing/gearing to unloaded amp draw.


...That having been said, I'm still using the 6A method and I hate myself. Gotta get that damn dyno finished!
Are you building your own dyno? I'm looking at doing the same, looking for software currently. I've seen a few different ways to go about it, I like the idea of a chassis dyno but figured I'd start with easiest configuration and build from there, any suggestions on where to find this sort of info, as far as formulas and schematics? Thanks in advance, Rooster
roosterreagan is offline   Reply With Quote
Old 04-27-2017, 06:40 PM   #33
Super Moderator
 
Marcos.J's Avatar
R/C Tech Elite Subscriber
 
Join Date: Sep 2003
Location: Semper Fi
Posts: 27,054
Trader Rating: 182 (100%+)
Default

Lap times is the best dyno
Ivan Dickson and Metalsoft like this.
Marcos.J is offline   Reply With Quote
Old 04-27-2017, 06:56 PM   #34
Tech Master
 
YoDog's Avatar
 
Join Date: Aug 2006
Location: Lompoc, Ca.
Posts: 1,659
Trader Rating: 26 (100%+)
Default

Quote:
Originally Posted by roosterreagan View Post
Are you building your own dyno? I'm looking at doing the same, looking for software currently. I've seen a few different ways to go about it, I like the idea of a chassis dyno but figured I'd start with easiest configuration and build from there, any suggestions on where to find this sort of info, as far as formulas and schematics? Thanks in advance, Rooster
Something like this one. They have some great software that they use too.
Check out their videos!
RC Brushless Chassis Dyno
__________________
R-Factor RC Products
AE- TC6.1WC, TC6.2, RSD6, B5M
CRC- GenX10 WGT & Pro10 Prototype, WTF1, Xti 1/12
R-Factor RC- TC4-R, P8 PanCar
Not as Fast as I want to be but too old to Whine about it... 8-)
YoDog is offline   Reply With Quote
Old 04-27-2017, 07:03 PM   #35
Tech Elite
 
Metalsoft's Avatar
 
Join Date: Jun 2009
Location: Nashville, TN
Posts: 2,023
Trader Rating: 69 (100%+)
Default

Quote:
Originally Posted by YoDog View Post
Something like this one. They have some great software that they use too.
Check out their videos!
RC Brushless Chassis Dyno
That is really cool.
__________________
Tamiya TB03 USGT - Custom Carbon fiber Chassis - Magoo Racing Inc....
Metalsoft is offline   Reply With Quote
Old 04-27-2017, 08:31 PM   #36
Tech Elite
 
howardcano's Avatar
 
Join Date: Jan 2012
Location: Olathe, KS
Posts: 3,610
Trader Rating: 35 (100%+)
Default

Quote:
Originally Posted by roosterreagan View Post
Are you building your own dyno? I'm looking at doing the same, looking for software currently. I've seen a few different ways to go about it, I like the idea of a chassis dyno but figured I'd start with easiest configuration and build from there, any suggestions on where to find this sort of info, as far as formulas and schematics? Thanks in advance, Rooster
I can provide you with a schematic, program, and spreadsheet. You just need to make or obtain a suitable flywheel. PM me if you are interested. Here's a quick peek:

R/C Tech Forums - View Single Post - The Homebuilt Dynamometer (Dyno)Thread!!!
__________________
Howard Cano
When race results are re-calculated using the IOF (Index Of Fun), I always win.
1993 ROAR 1/8 Pan National Champion
howardcano is offline   Reply With Quote
Old 05-12-2017, 05:06 PM   #37
Tech Addict
 
silden's Avatar
R/C Tech Elite Subscriber
 
Join Date: Dec 2012
Location: Los Angeles
Posts: 678
Trader Rating: 12 (100%+)
Default West Coast R/C Works Dyno Controller

Quote:
Originally Posted by YoDog View Post
Something like this one. They have some great software that they use too.
Check out their videos!
RC Brushless Chassis Dyno
The mechanical part of the dyno is great, but I don't like the the suggested software. The
The software isn't as stable as it should be. You have 3 different software programs running at the same time. This isn't the fault of McPappy he tried to find a doable solution with available stuff on the market today.
I have one of the dyno's and tested the software intensively.
After a week of trail and error I decided to design and test my own standalone dyno controller. The controller is still in beta testing and I currently wait for the updated pcb to come from the factory. The controller can be setup from a display or through the BT app. The device logs the motor RPM, battery voltage and amp draw with 200hz. The controller is designed to work with chassis and motor dyno's.


Let's talk about timing....-img_1488.jpg

Let's talk about timing....-img_1486.jpg

Let's talk about timing....-img_1487.jpg
__________________
West Coast R/C Works
West Coast R/C Works Shapeways Store
LRP America
Ulti Tires
BlackFriday 25% Promo Code: BFCM25

Last edited by silden; 05-12-2017 at 05:19 PM.
silden is offline   Reply With Quote
Old 05-12-2017, 05:09 PM   #38
Tech Addict
 
silden's Avatar
R/C Tech Elite Subscriber
 
Join Date: Dec 2012
Location: Los Angeles
Posts: 678
Trader Rating: 12 (100%+)
Default

Quote:
Originally Posted by howardcano View Post
I can provide you with a schematic, program, and spreadsheet. You just need to make or obtain a suitable flywheel. PM me if you are interested. Here's a quick peek:

R/C Tech Forums - View Single Post - The Homebuilt Dynamometer (Dyno)Thread!!!
Howard,
Can you may give me some insight in to the use of the Resistors inline of the motor wires? Isn't that affecting the speed controller/ slowing down the motor trigger on each phase? I'm not criticizing your design. I like to lean from your knowledge.

Thank you
Denis
__________________
West Coast R/C Works
West Coast R/C Works Shapeways Store
LRP America
Ulti Tires
BlackFriday 25% Promo Code: BFCM25
silden is offline   Reply With Quote
Old 05-12-2017, 05:57 PM   #39
Suspended
 
Join Date: Feb 2011
Posts: 6,262
Trader Rating: 1 (100%+)
Default

I am sorry to say guys but the best dynos are still the ones that measure the power at the wheels of your Rc cars, and will show you in realtime what your total car setup(not just the motor) is putting on the ground... Motor timing's effect on power at the wheels should be what we strive to measure...I know these dynos are expensive, but that's life....
bertrandsv87 is online now   Reply With Quote
Old 05-12-2017, 06:04 PM   #40
Tech Addict
 
silden's Avatar
R/C Tech Elite Subscriber
 
Join Date: Dec 2012
Location: Los Angeles
Posts: 678
Trader Rating: 12 (100%+)
Default

The Controller I'm developing is usable with chassis and motor dynos as well.
both types of dynos are telling you the power been delivered by the motor.
The chassis dyno can help you to find the right gearing, but the motor only dyno makes it easier to find the right timing first.
__________________
West Coast R/C Works
West Coast R/C Works Shapeways Store
LRP America
Ulti Tires
BlackFriday 25% Promo Code: BFCM25
silden is offline   Reply With Quote
Old 05-12-2017, 06:55 PM   #41
Tech Elite
 
howardcano's Avatar
 
Join Date: Jan 2012
Location: Olathe, KS
Posts: 3,610
Trader Rating: 35 (100%+)
Default

Quote:
Originally Posted by silden View Post
Howard,
Can you may give me some insight in to the use of the Resistors inline of the motor wires? Isn't that affecting the speed controller/ slowing down the motor trigger on each phase? I'm not criticizing your design. I like to lean from your knowledge.

Thank you
Denis
The resistors are for test only; I used them to simulate a heavier flywheel until I finally got one. The only effect they have is to reduce the motor's torque and therefore power, much the same as winding the motor with much finer wire. That's nothing one would want to do for actual motor testing!

If you (or anyone else, for that matter) would like the documentation for the design, send me a PM. The electronics and code for the data acquisition is done, along with a spreadsheet to do the calculations.

It might be an excellent starting point for you, or simply give you some ideas for your project.
__________________
Howard Cano
When race results are re-calculated using the IOF (Index Of Fun), I always win.
1993 ROAR 1/8 Pan National Champion
howardcano is offline   Reply With Quote
Reply

Similar Threads
Thread Thread Starter Forum Replies Last Post
ROAR STOCK motors.... rule changes regarding BRUSHLESS Joel Lagace Electric On-Road 164 08-28-2007 09:07 PM



Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools Search this Thread
Search this Thread:

Advanced Search

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 On
Pingbacks are On
Refbacks are Off



All times are GMT -7. It is currently 10:53 PM.


Powered By: vBulletin v3.9.2.1
Privacy Policy | Terms of Use | Advertise Content © 2001-2011 RCTech.net