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Old 09-23-2011, 04:32 AM   #496
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Hi,
I got a Octa 4.5 X12 and it draws big amps... On the motor checker it cuts out saying amps too high!!!
I tried different rotors and sensor is fine. Motor never ran hot, not even close to 80 Celcius... ??? Bearings also replaced... Have a SpeedPassion ver. 2 that does the same?
It's only run 3 weekends so any suggestions?

Thanks

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Old 10-03-2011, 06:12 AM   #497
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Default LRP x12 17.5

Is there anybody out there using the LRP x12 17.5 with a boosted ESC?

Any tips for running it compared to other motors? Bigger pinion, hotter, timing?

Ben
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Old 10-09-2011, 04:50 AM   #498
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I recently purchased an Extreme BMC-01 brushless motor checker. After using it for the first time today, I found the results somewhat confusing. The motor checker has 8 throttle positions, and presents the rpm, kV and Amps for each Throttle Position.

The following image shows the test results for three separate LRP X12 17.5T motors.



The old motor was only used at one race meet as it slowed considerably in the last race heat. I think I either over geared it or over boosted it, causing it to get too hot.

The other two motors are brand new, never been raced. When I tested 'New Motor 1' and compared it to the old slow motor I noted that across the throttle range the rpm and kV are similar, but the Amps drawn by 'New Motor 1' are significantly higher, and double at Throttle Position 8.

Then when I tested 'New Motor 2', I expected that it would be almost identical to 'New Motor 1. However, 'New Motor 2' draws significantly more Amps than 'New Motor 1', and the Amps drawn at Throttle Position 8 are more than double.

Does this mean that one of the new motors is a dud? Note that I don't have time to test them on the race track yet.

Does drawing more Amps at a set Throttle Position mean that the motor is using more power and hence, is a better motor?

Any help with my understanding of these results would be appreciated. Thanks.
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Old 10-09-2011, 09:41 AM   #499
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First check the play on the new motor 2.
I had 2 13.5 LRP X12 motors here that where shimmed incorrectly(they where very thight) and did run high rpm but took a lot of amps.
Shimmed it correctly and the amps went down and the RPM was raised a bit.
Your old motor has a bad rotor in it due to the heat(almost no magnetic field).
Replace the rotor in the old motor and it will run ok again(try on of the rotors of the new motors).
When you shim the rotor in the housing, be sure that the sensor side is as close to the sensorboard as possible.
This will result in a faster motor.

regards Roy
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Old 10-10-2011, 08:38 AM   #500
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Thanks for your advice Roy. I checked the end play on both the new motors, and they seem about the same. Hence, I did a 5 minute run in on each motor on the test bench. Now I need to take the motors to the track to compare their relative speeds.

I actually have two old and slow motors, for which I bought a new 12.5 mm Works Team rotor for each. It took me a while to devise a method to get the new rotors in place ... those magnets are strong.

On one of the old motors, with a new rotor, the test bench gave a current draw of 2.6 Amps at peak revs, which is about half way between the two new motors. It will be interesting to see how this 'refurbished' motor performs compared to the two new motors. This old motor also had the solder melted off one of the internal connections. That is, where the three wires connect to the 'wavy' metal ring inside the can at the pinion end. I soldered it back on.

The second old motor had two out of the three internal connections unsoldered. I presume that the solder melted when the motor got too hot. Installing the Works Team rotor into this old motor was harder than the other old motor. Subsequently, I found after completing the assembly that I cannot turn the rotor by hand at all. The rotor appears to be jamming against the stator somehow. Hence, I gave up with this motor.

I am still not quite sure what the test bench results mean in practice, but the 'impression' that I am getting so far is described below. But note this is only my intuition so far, as I haven't been able to find any meaningfull data on the internet. If my intuition is all wrong, please don't hesitate to tell me.
  • Need high revs.
  • Need high kV (thousands of revs per volt)
  • Don't want low Amps drawn. eg: 0.8 Amps at full throttle is too low, perhaps indicates that the rotor magnet strength is gone.
  • Don't want Amps drawn being too high as this may indicate high rolling resistance within the motor due to dodgy bearings or something rubbing.
  • Perhaps want the Amps drawn at full throttle to be mid-range, say 1.6 Amps to 2.6 Amps.

Now all I need to do is test all three remaining motors, which I need to do soon as we have a race meet this Sunday. I use plugs for the three leads between the motor and the ESC. Hence, I can easily and quite quickly test multiple motors in one session.
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Old 10-13-2011, 07:47 PM   #501
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I'm running the lrp spx8 speedo with the lrp x12 3.5t motor. I'm running a 4s setup, do you see problems with the motor overheating or the esc overheating. I would be gearing down to give the motor less stress.
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Old 10-13-2011, 10:41 PM   #502
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Greetings!!!

I am running a X12, 17.5 "blinky" mode (using a SXX Stock Spec, software version 4.4) in a touring car. Am unsure of how to gear the car. I heard that this motor has a lot of top end power and should be geared for acceleration instead of top end speed. Is this correct?

How should gearing change using the 4 dot insert compared to the stock insert? Am not concerned about track size, just need to know how the inserts affect the gearing.

Thanks
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Old 10-14-2011, 12:07 AM   #503
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Quote:
Originally Posted by Three View Post
Greetings!!!

I am running a X12, 17.5 "blinky" mode (using a SXX Stock Spec, software version 4.4) in a touring car. Am unsure of how to gear the car. I heard that this motor has a lot of top end power and should be geared for acceleration instead of top end speed. Is this correct?

How should gearing change using the 4 dot insert compared to the stock insert? Am not concerned about track size, just need to know how the inserts affect the gearing.

Thanks
im using the same combo and uses 2dot insert and is gearing 4.0 on a 25x15meter track :-) stock insert is 4dot but fewer dots gives more timing and therefore more topend :-)

steven
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Old 10-14-2011, 06:13 AM   #504
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Originally Posted by StevenOlsen View Post
im using the same combo and uses 2dot insert and is gearing 4.0 on a 25x15meter track :-) stock insert is 4dot but fewer dots gives more timing and therefore more topend :-)

steven
This motor makes a LOT of torque with lower timing, so sometimes the 4 dot (with more torque) will give you more speed because it'll pull a larger pinion than any other insert will with more RPM!

4.0/4 dot is the place to start with gearing. Adjust gearing with temps, then fine tune with timing inserts.

Have a high amp draw fan blowing on your motor.

X12s like it hot.
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Old 10-14-2011, 06:29 AM   #505
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I am using the X12 13.5 with the factory settings on the motor in combo with a Tekin RS with timing,boost and all.
Have a FDR of 7.92 and it's reving up to just about 3 quarters of the straight.
This motor is mind blowing fast.
A lot of torque out of the corners and all the speed you can dream off.
Temps at the end of a 8 minute heat is about 60 tot 65 degrees celcius
Running it in a TRF416X at this circuit http://www.youtube.com/watch?v=0y00uwKLjoA
Don't look at the speed in the clip as this was in 2009 with 5 cells and 10.5
What i am driving is faster and there is still more improvement for a faster time( personal best is 21.555 fastest time 13.5 boosted 21.2)

regards Roy
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Old 10-14-2011, 07:59 AM   #506
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So the motor should be geared for top end speed when using lower timing?
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Old 10-14-2011, 09:00 AM   #507
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Lower timing= more torque= bigger pinion=lower FDR
High timing=more RPM=smaller pinion= higher FDR
Top speed can be the same on both FDR but on a big track you want more top RPM and on a small tech track you wan't more torque out of the corners.

regards Roy

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So the motor should be geared for top end speed when using lower timing?
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Old 10-14-2011, 03:56 PM   #508
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Thank you. That was what I needed to know. Now if I could just learn how to drive.
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Old 10-16-2011, 02:45 PM   #509
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Played with gearing today (both pinion and spur gears) and motor still seems flat. No acceleration kick or top end. Not sure of what else to try.
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Old 10-16-2011, 02:48 PM   #510
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The old or the new motors?
You sure there is nothing wrong with the ESC??
Or sensor cable/board?

regards Roy

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Played with gearing today (both pinion and spur gears) and motor still seems flat. No acceleration kick or top end. Not sure of what else to try.
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