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Old 07-24-2013, 05:03 PM   #16
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I started working on a dyno last night. I had a fantom laying around and I was looking thru my stuff and found a ko propo positive negative adapter to abc to run a brushless motor that they gave away in Vegas one year. I soldered it to the dyno power wires and threw in a brushless motor . Hit run and it ran the motor showed a screen with rpm but no amp draw or other info . Anybody have any idea if I can make this work to show the amp draw and watts .
I'm not sure exactly what the Ko propo "adapter" is, but I've done this using an ESC and a servo tester. The Fantom seems to have a problem with amp draw readings, generally reading too low to be believable. With 8.5 & 10.5 motors, it produced believable efficiency numbers, but when I dropped down to 17.5's it reported efficiency of 170%. The power, torque & RPM numbers are useful, just not amps (and efficiency, since it's calculated by amps). I think that maybe it's a timing problem. It's not collecting amp draw data at the same instant as the RPM data, possibly because the higher-turn motors reach top speed so quickly. Very few data points to calculate from. Maybe the optional steel flywheel would fix this, but I haven't got one to try.

Another problem with some ESCs is the "wake-up" time. Many ESCs need a second or two after power comes on before they will respond to throttle input, but the dyno gives up, shuts down and displays a fault message before the ESC starts. Some ESCs also need to see neutral before they will arm. The old Novak GTB works fine, but most others don't.
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Old 07-25-2013, 06:15 AM   #17
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The issue with a Fantom is that it is time based. I use it but the amp readings won't be spot on. The issue is that the ESC pulses the power to a brushless motor and the computer takes readings a specific time slots. The wake up of a ESC is why you need to have it powered before starting the test and it needs to go to full throttle as fast as possible. Radio system response can be an issue but with practice you get the hang of it. I get reasonably repeatable numbers on motors tested on multiple pulls. If I had a choice I would use a TurboDyno but I already owned the Fantom.
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Last edited by old_dude; 11-12-2013 at 11:04 AM.
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Old 07-25-2013, 08:40 AM   #18
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The Fantom dyno was designed for brushed motors but it works well for brush less as long as you have a good ESC with no wakeup time. The Tekin RS works good. Best way is to power a servo controller with a receiver pack. Calibrate the ESC and set throttle to full, then run the dyno.

Th key thing to dynos is using the same one and test all your variables and as much as possible.
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Old 07-25-2013, 04:31 PM   #19
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http://www.hobbytalk.com/bbs1/showth...brushless+dyno
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Old 07-25-2013, 08:49 PM   #20
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So it looks like I may try to find a CE Turbo Dyno. Someone at my track uses one and it seems like the way to go. I need a dyno type that places a load on the motor being tested. I also like the mcpappys idea and may try to build something similar.
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Old 07-25-2013, 09:38 PM   #21
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I thought the ko part that has a red and black wire going in and a b c coming out to run it would be alright . It runs reads rpm the exits . I'm going to try a speed passion dyno mounted to the fantom for weight and run it the way no I just need a speedo
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Old 11-11-2013, 04:31 PM   #22
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Quote:
Originally Posted by AARON YOUNG View Post
I started working on a dyno last night. I had a fantom laying around and I was looking thru my stuff and found a ko propo positive negative adapter to abc to run a brushless motor that they gave away in Vegas one year. I soldered it to the dyno power wires and threw in a brushless motor . Hit run and it ran the motor showed a screen with rpm but no amp draw or other info . Anybody have any idea if I can make this work to show the amp draw and watts .
Put a Amp Draw Meter in line with it would prob be the easiest.
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Old 11-12-2013, 08:20 AM   #23
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I bought a McPappy in 2012. Flywheel was included. Nice piece of kit I must say. I did make up various collars etc on my lathe to help with the different layouts. Bought an Eagle tree datalogger, sensors and digital readout panel.

Just an opinion but whilst results were interesting, personally I did not think they were really all that helpful with regard to on road circuit racing, for me at least. One of the reasons I felt was because the way electric motors make their power is rather load dependent and this varies a lot around a circuit, and from circuit to circuit.

I did read a lot of helpful posts by John Stranahan some years back. He makes a very good case for oval racers to use the dyno however.

As I had the gear, I placed the Eagle Tree system in the car and went out on the track with it. Now that was a revelation. Gives a good insight into how boost affects current draw, and therefore how much you can use, and how quickly it can be applied before it just turns to heat. This is good to know.

When you have enough data to correlate into something meaningful it is possible to interpret the readings from an ordinary motor tester very effectively. So I just use an Extemerc tester from RCMarket or whatever (quite cheap) and a Fantom Facts Machine Jr gauss meter these days. TBH I hardly ever touch the settings now. The rules mean that overall motor performance is very similar between brands once you're in the sweet spot.

Sadly for me tuning the car and driving it are much more important to laptime

Last edited by hana166; 11-12-2013 at 08:33 AM.
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Old 11-12-2013, 11:10 AM   #24
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What you observed is very true. I have always said that on-road racing is chassis and driver in near equal parts with 20% or so saved for the motor/gear/battery combo. On the oval it is more like split between the motor/gear/battery and the chassis with about 20% saved for the driver. Those numbers vary based on opinion but the order is close to true.
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