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Old 10-03-2003, 09:36 AM   #1
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Default How to maintain a motor

Hi, I am new to RC and used to play 1:12 for a while. Now, I just got my 1:10 XRAY and using 12-13 turn motor. I found the lifetime for both commutator and brush are much shorter than I used to play 1:12. Is this normal? For example, I have a 12 turn motor and I need to cut the comm every 3 pack of batteries. It doesn't seem the motor is overheat thou.
I still remember I could run my 1:12 for at least 6-8 pack of batteries before I need to ask somebody to cut the comm for me.
Also, should I install the "DIODE" to the motor? Does it help to reduce spark? I do apply quite a lot of break during the run. Thank you!
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Old 10-03-2003, 10:05 AM   #2
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touring cars are more weight and since it's not direct drive drivetrain they wear more on the comm/brushes therefore you need to cut it more. Mod motors especially. If you go to run a stock motor, you'll see less drop off in performance than a 10-12 turn since stock is 27 turn with fixed 24 timing.

I'm assuming by diode you're talking about a Schottky diode. This is used for forward only ESC's. The benifit to using them is that it offers more consistent braking, more efficient motor operation and allow cooler operation of electronic speed control.

Hope this helps.

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Old 10-03-2003, 10:10 AM   #3
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Thanks, no wonder I noted my ESC is a bit warm after each run. I didn't have this problem before when I ran my 1:12, because I install the schottky-Diode on my motors. Thank you! By the way, doesn't anyone knows any motor maintainence guide webpage?
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Old 10-03-2003, 02:38 PM   #4
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what ESC are you using?
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Old 10-03-2003, 05:36 PM   #5
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What exactly does the Schotky DO? Does it eliminate reverse voltage from the collapse of the magnetic feild? I belive this is called "Fly-Back".
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Old 10-03-2003, 05:47 PM   #6
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Default How to maintain a motor

Assuming you ran 4 cells in the 12th scale car and are now running 6 cells in the touring car.....you are putting more voltage to the motor and therefore drawing more current through the speed control causing the heat that was't there with 4 cells. The extra voltage will also increase the RPM's the motor turns during your race causing more wear on the comm and brushes.

Good Racing
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Old 10-03-2003, 07:11 PM   #7
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Default Re: How to maintain a motor

Quote:
Originally posted by proguy
Assuming you ran 4 cells in the 12th scale car and are now running 6 cells in the touring car.....you are putting more voltage to the motor and therefore drawing more current through the speed control causing the heat that was't there with 4 cells. The extra voltage will also increase the RPM's the motor turns during your race causing more wear on the comm and brushes.

Good Racing
I ran 6 cells on my 1:12....yes, it was "very" fast. I was the only one who ran a 6 cells 1:12 on my local track.
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Old 10-03-2003, 07:18 PM   #8
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Quote:
Originally posted by John Fontaine
what ESC are you using?
LRP Quantum competition
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Old 10-03-2003, 07:31 PM   #9
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I thought 6 cells was against the rules?
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Old 10-03-2003, 07:33 PM   #10
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Quote:
Originally posted by Smartazz07
I thought 6 cells was against the rules?
Oh, I am not into any race, just bashing on the track only.
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Old 10-03-2003, 10:19 PM   #11
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Quote:
Originally posted by discus18
By the way, doesn't anyone knows any motor maintainence guide webpage?
Team RCV has got everything you'll every want to know about motors and tuning
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Old 10-03-2003, 10:43 PM   #12
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Quote:
Originally posted by discus18
By the way, doesn't anyone knows any motor maintainence guide webpage?
http://www.motortuningsecrets.com/tunestockmotor.html
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Old 10-04-2003, 12:04 AM   #13
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Quote:
Originally posted by ChrisO
Team RCV has got everything you'll every want to know about motors and tuning
OK, I have to pick one big huge nit with a bit of information on that page:
Quote:
Question: You made a comment that your theory for the electrical flow through a brush to the comm, was primarily around the edges of the brush.

<snip>

BJ's Answer: I didn't exactly say the current transfers only by the edges. I believe I said it likes to travel that way. Kind of like path of less resistance and all that.

<snip>
It's just not true. Current flows at the edge of a conductor only at very very very high frequencies, in the MHz and GHz range, and it's one of the reasons why Coaxial cables are made the way they are. The specific phenomenon is called skin effect, and is used to sell a lot of insanely expensive speaker cables to folks who don't know any better. It doesn't happen at DC. For low frequencies (<100kHz) you want lots of copper, because the cross sectional area of the conductor is all that really matters.

I'm not sure why the hole works either, but it sure ain't because the charge want to move to the outside...

-dave
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Old 10-05-2003, 03:21 AM   #14
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Quote:
Originally posted by dpaton
OK, I have to pick one big huge nit with a bit of information on that page:

It's just not true. Current flows at the edge of a conductor only at very very very high frequencies, in the MHz and GHz range,
-dave
most speedos work at 4 MHz
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Old 10-05-2003, 09:56 AM   #15
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Quote:
Originally posted by TC3
most speedos work at 4 MHz
Actually, most speedos run at around 4kHz, which is a lot (three zeros) slower, and well out of the skin-effect region. Also, you know those big caps that all the latest and greatest ESCs have on them? They turn the PWM output into nice, relatively clean, DC.

As a point of note, if skin effect mattered, the area that would carry the majority fo the charge would be about 1/3 the thickness of a human hair. When dealing with skin-effect. any amount of conductor other than the skin area is just fine. There's no loss, it just doesn't carry much of the total current.

If it really came into play, we'd all use coax to hook the ESC to the motor. There's a reason we don't...



-dave
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