13LikesLet's talk about timing....
04-26-2017, 06:29 AM
#31
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! 
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! 
04-27-2017, 05:26 PM
#32
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
04-27-2017, 05:56 PM
#34
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
Check out their videos!
RC Brushless Chassis Dyno
04-27-2017, 06:03 PM
#35
Something like this one. They have some great software that they use too.
Check out their videos!
RC Brushless Chassis Dyno
Check out their videos!
RC Brushless Chassis Dyno
04-27-2017, 07:31 PM
#36
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
R/C Tech Forums - View Single Post - The Homebuilt Dynamometer (Dyno)Thread!!!
05-12-2017, 04:06 PM
#37
West Coast R/C Works Dyno Controller
Something like this one. They have some great software that they use too.
Check out their videos!
RC Brushless Chassis Dyno
Check out their videos!
RC Brushless Chassis Dyno
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.
Last edited by silden; 05-12-2017 at 04:19 PM.
05-12-2017, 04:09 PM
#38
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!!!
R/C Tech Forums - View Single Post - The Homebuilt Dynamometer (Dyno)Thread!!!
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
05-12-2017, 04:57 PM
#39
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....
05-12-2017, 05:04 PM
#40
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.
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.
05-12-2017, 05:55 PM
#41
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
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
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.
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