Infraction data log help

[LibertyMKiii]

I’ve got it set at no smoothing. ?

Nope, I’ve got the gearing set the same for both runs at 35/34. But I’ll double check just to make sure!

Based on Robert's comments I would recommend setting the log's gearing setting at 34/34 so we can see accurate numbers.
Setting it this way will show the motor RPMs instead of the center spool RPMs.

 

[The Donut Man]

Thanks Robert that is very helpful, and I appreciate the background on why it is this way.

This is a game-changer for my data. I just switched one of my logs over to 1/1 gearing and my max RPM went from ~36k to 43,813 RPM. My minimum voltage in the run is 20 volts which, when multiplied by motor kv yields (20.0 V) X (2200kv) = 44,000 RPM. This means that if my motor's kv is actually 2200, then I'm only 187 RPM shy of the no-load RPM. This is important because it shows how much the motor has to give and it'll be obvious once it really gets taxed by higher gearing. I had always thought that for a 2200kv motor, 8S was necessary to break 40k RPMs but that's not the case!

 

[robert@castle]

This is a game-changer for my data. I just switched one of my logs over to 1/1 gearing and my max RPM went from ~36k to 43,813 RPM. My minimum voltage in the run is 20 volts which, when multiplied by motor kv yields (20.0 V) X (2200kv) = 44,000 RPM. This means that if my motor's kv is actually 2200, then I'm only 187 RPM shy of the no-load RPM. This is important because it shows how much the motor has to give and it'll be obvious once it really gets taxed by higher gearing. I had always thought that for a 2200kv motor, 8S was necessary to break 40k RPMs but that's not the case!

Take off your pinion and give it full throttle while logging to see your max unloaded RPM to calculate your motor's actual KV. There is quite the variance in KV even in motors that claim to be the exact same thing because there is a lot of variables that are very hard to control in production. KV can also change after the motor is made, the magnets can get slightly weaker causing the KV to rise. So it's not a bad idea to check unloaded KV every so often. It's also a good way to listen to the motor bearings and check they are not going bad.

Another thing to keep in mind if you are comparing several "identical" motors is that torque is inverse of KV. For example, if you had three 1717-1650KV motors that tested at 1625,1640, and 1670KV. The 1625KV motor will have the most torque. So while the 1670kv motor will have the most unloaded RPM, it may struggle to get as much RPM in vehicle as the 1625KV motor because it has less torque to overcome the load. You might need to gear down a tooth to reach as high of a potential speed with the motor.

 

[LibertyMKiii]

This is a game-changer for my data. I just switched one of my logs over to 1/1 gearing and my max RPM went from ~36k to 43,813 RPM. My minimum voltage in the run is 20 volts which, when multiplied by motor kv yields (20.0 V) X (2200kv) = 44,000 RPM. This means that if my motor's kv is actually 2200, then I'm only 187 RPM shy of the no-load RPM. This is important because it shows how much the motor has to give and it'll be obvious once it really gets taxed by higher gearing. I had always thought that for a 2200kv motor, 8S was necessary to break 40k RPMs but that's not the case!

Thanks for brining up the gearing stuff by the way. I had no idea it was changing the results in the data.
It is a game changer indeed.

Take off your pinion and give it full throttle while logging to see your max unloaded RPM to calculate your motor's actual KV. There is quite the variance in KV even in motors that claim to be the exact same thing because there is a lot of variables that are very hard to control in production. KV can also change after the motor is made, the magnets can get slightly weaker causing the KV to rise. So it's not a bad idea to check unloaded KV every so often. It's also a good way to listen to the motor bearings and check they are not going bad.

Cool ? now I can sell off my SkyRc motor KV tester!

 

[jondilly1974]

My mind has been blown in this thread many times ?

 

[The Donut Man]

I’m just really grateful that there are others in the speed run game who are willing and happy to show their data logs and talk through them. A year ago I had to look really hard to find this kind of info!

 

[Notoriousone]

When I change the gearing/poles in the Castle link software, the only thing I see that changes is my RPM. What else are you guys seeing change? Each time I download data from the ESC and analyze it in Castle link I set the gearing, KV, and pole count for the motor. Attached is my run of my Hobao Hyper VTe. It hit 132mph, my PB. On this car I was running 34/34. The thing I wonder about with this is the motor temp of 196degrees, I don't know how it got that considering I wasn't running a sensored system and it had no motor temp sensor..

 

[The Donut Man]

When I change the gearing/poles in the Castle link software, the only thing I see that changes is my RPM. What else are you guys seeing change? Each time I download data from the ESC and analyze it in Castle link I set the gearing, KV, and pole count for the motor. Attached is my run of my Hobao Hyper VTe. It hit 132mph, my PB. On this car I was running 34/34. The thing I wonder about with this is the motor temp of 196degrees, I don't know how it got that considering I wasn't running a sensored system and it had no motor temp sensor..

The only thing the gearing ratio changes is the RPM, so for your 34/34 run the graph shows the actual motor RPM. To recap what Robert said, you always want a 1/1 ratio in the software to reflect the RPM at the motor. As for motor temp, I have no idea. I would count it as unreliable data since we don't know its source, but it could be interesting to compare it to external can temperatures. Congrats on the PB by the way! You have me by 1 mph right now

 

[Mr.Duke]

Take off your pinion and give it full throttle while logging to see your max unloaded RPM to calculate your motor's actual KV. There is quite the variance in KV even in motors that claim to be the exact same thing because there is a lot of variables that are very hard to control in production. KV can also change after the motor is made, the magnets can get slightly weaker causing the KV to rise. So it's not a bad idea to check unloaded KV every so often. It's also a good way to listen to the motor bearings and check they are not going bad.

Another thing to keep in mind if you are comparing several "identical" motors is that torque is inverse of KV. For example, if you had three 1717-1650KV motors that tested at 1625,1640, and 1670KV. The 1625KV motor will have the most torque. So while the 1670kv motor will have the most unloaded RPM, it may struggle to get as much RPM in vehicle as the 1625KV motor because it has less torque to overcome the load. You might need to gear down a tooth to reach as high of a potential speed with the motor.

This is highly valuable information and knowledge that you’re sharing and I’m extremely thankful that you’re part of the group, shedding light on key components for what it takes to make successful speed runs for these machines and how to decipher the information in these logs ?

 

[LibertyMKiii]

@robert@castle
Since we are getting into setting of the logs, what impact to the data does the motor KV selection have?

 

[jondilly1974]

Hoping it's OK to add to the discussion here OP.

Here is my data from my 115mph Infraction run yesterday. TP 4050CM 2300kv MMX8S 27/34

 

[LibertyMKiii]

Hoping it's OK to add to the discussion here OP.

Here is my data from my 115mph Infraction run yesterday. TP 4050CM 2300kv MMX8S 27/34

View attachment 104533

View attachment 104532

I know the car caught air and landed up side down but 84k rpms?

 

[rotauq]

84k rpms is ridiculous, but so is 11.8 kW on a 4050 can. Motor timing must be set real high.

 

[jondilly1974]

Default timing 10

 

[LibertyMKiii]

Default timing 10

This sort of goes back to my concerns about RPM Accuracy in the logs.
Was the smoothing turned off for this log?

2300kv * 33.3V (maybe less voltage at that time) = 76,590 rpm
The logs would indicate you have a 2500+ kv motor

 

[jondilly1974]

I am looking at the data again and it keeps giving me different values. I put in 1:1 gearing 2300kv 4 poles as Robert said to do. Smoothing is off. Now when I open the data it gives me different values each time? ?‍

Here is the entire log for two runs with 1:1 2300 4

And here is the data with 29/34 2300kv 4 poles

The first pass was the 115mph run in my video. The second pass was 116mph and ended in the field.

115 zoomed

116 zoomed

And here is todays pass of 127mph that ended in the field as well

1:1 2300kv 4 poles

 

[LibertyMKiii]

Those last 2 logs seem to be the only ones with correct RPM values.
Hopefully today's field trip didn't damage anything? It seems those cars have an off-road bias lately

 

[jondilly1974]

Those last 2 logs seem to be the only one with correct RPM values.
Hopefully today's field trip didn't damage anything? It seems those cars have an off-road bias lately

Just bent the splitter as always. A little heat will get it straight again.

 

[Mr.Duke]

Looks like each time the esc cut power due to low voltage
Get rid of the value in that table to avoid it kicking on and fluctuating full power at the top of those pulls

 

[rotauq]

Looks like each time the esc cut power due to low voltage
Get rid of the value in that table to avoid it kicking on and fluctuating full power at the top of those pulls

Looking at the voltage drop curve it might actually be perfectly matched to the max amp draw the batteries can take. Last few percentages of the throttle in could be a tiny bit smoother to delay the amp draw/voltage drop. Not that i can do better, definitely nice throttle control on the third run. That's seems to make the difference between 115-116 and 127mph