# Advancing a motor



## major (Apr 4, 2008)

Matej said:


> Hello,
> There are already a few conversations on the topic, but there does not seem to be a clear consensus.
> I am curious how far the brushes may be advanced before it is too much. In one thread, someone warned not to exceed 10 degrees, while in another, a person stated it is perfectly fine to advance more than 20 degrees.
> 
> ...


Rule of thumb: You lose 2% of your torque per amp per degree.

I would think 10° is as far as one needs to advance. Be sure your reference is neutral. 

Above applies to 4 pole non interpole motors.

major


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## Matej (Dec 4, 2015)

Thank you. The motor I have is actually 5-pole. May I ask what will need to be done differently?

Out of pure curiosity, how much are Warp motors advanced from the factory?


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## major (Apr 4, 2008)

Matej said:


> Thank you. The motor I have is actually 5-pole. May I ask what will need to be done differently?
> 
> Out of pure curiosity, how much are Warp motors advanced from the factory?


Motor poles always come in pairs, North and South, like magnets. Undoubtedly it will have one brush holder per pole.

Unsure about factory advance for motors. 

major


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## Matej (Dec 4, 2015)

Sorry for the misunderstanding, I meant five terminals, not poles.


Judging by how the terminals on Warp motors are offset, I wonder if it may be assumed that is how far they are advanced, or if it is purely a design coincidence.


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## dcb (Dec 5, 2009)

that information is easily available with a google search:
https://www.google.com/webhp?source...UTF-8#q=warp+9+netgain+timing+advance+degrees

returns netgain faq
http://www.go-ev.com/PDFs/005_008_SU_NGT_FAQ.pdf

search that doc for "degrees" finds:

```
9. How do I know how much to advance the timing on a motor?
All new WarP Motors have pre-drilled holes that allow the commutator end-bell to be removed and
the brushes repositioned in a neutral, or an advanced position, either CWDE or CCWDE. The
WarP, ImPulse , and TransWarP Motors are each advanced ~12 degrees. The WarP 8 motor
is advanced ~10 degrees. The amount of advancement is based upon the width of the brushes, the
number of commutator bars, the diameter of the commutator and various other factors that are
monitored when the motor is run on a dynomometer.
```


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## Matej (Dec 4, 2015)

Thank you for posting that. Good to have the information all in one thread.


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## Matej (Dec 4, 2015)

A related question, if I may.
According to the Warp documentation dcb posted, advancing the motor is generally beneficial above 96V.

So, for example, if I want to run a Warp9 at around 80V, would it actually be better to set the timing to the neutral position?
By better I mean, will I get more torque and power at 80V in neutral timing?

And what if I decide to up the voltage to run it at the threshold of 96V? Will it still perform better neutrally timed, but be more prone to possible damage?

Finally, how is RPM affected by neutral versus advanced timing? At 80V, will the motor spin faster neutrally timed or advanced?

Thanks for any insight.


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## major (Apr 4, 2008)

Matej said:


> A related question, if I may.
> According to the Warp documentation dcb posted, advancing the motor is generally beneficial above 96V.
> 
> So, for example, if I want to run a Warp9 at around 80V, would it actually be better to set the timing to the neutral position?
> ...


I'd leave it advanced unless it will be run in reverse rotation. We used to advance all large unidirectional motors not having interpoles. And brush advance is a form of field weakening so it does increase RPM at lighter loads. At moderate loads it will be only a few percent and likely not noticed at heavy loads.

major


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## galderdi (Nov 17, 2015)

I have advanced my ADC 9 inch to 10 degrees. 

It is running great however it is currently reversing through a gearbox. I am planning to implement a reversing contactor. I will put throttle limits in place to ensure I can't accelerate in reverse so fast that it will start arcing.

But it got me thinking. Maybe I should bring it back towards neutral. 

On dead neutral it did arch something fierce mid way through the revs. So then I advanced it and no more arcing. But I didn't try it at an angle in between.

I am only running a maximum of 172v anyway. So I wonder if a smaller advance angle would give a better compromise?

0 degrees = great torque, great reversing, terrible revs/arcing
10 degrees = OK torque, great revs, terrible reversing
Maybe 5 degress would = good torque, good revs and good reversing 

A quick side note: I will be accelerating fairly hard in reverse as my motorsport requires reversing during the time trials. But I figure reverse of around 70% of forward would be fine. Any more than that would be impossible to control in reverse anyway.

Any suggestions? There is a third set of predrilled holes but I don't think they are at 5 degrees looks more like 3 degress to me.


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## major (Apr 4, 2008)

Hi gald,

Only 172V? I doubt you ever apply near that to the motor. Anyway, years ago, and maybe some today, motor manufacturers would advance unidirectional motors like forklift pump drives a standard 4.5°. Those were used at 24-72V. When applying similar designs to hobbyist EVs the 4.5°shift was used up to 96V although some guys ran higher V. Unknown if they adjusted advance.

Commutation is such a black art I can't say when you'll arc or zorch. Gut feeling is 4 or 5° would be a good try. 70% current limit in reverse will undoubtedly arc. Is it tolerable? ?

Split brushes also called dual wafer might help. Careful that an arcing event doesn't strip the comm film and cause dusting/rapid brush wear.

Good luck and go fast (or quickly),

major


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## galderdi (Nov 17, 2015)

Thanks Major. Confirms what I was expecting to hear.

I would prefer to avoid the arcing entirely but I'll see how I go. The great news is that I have a few options up my sleeve.

Firstly I do two main forms of motorsport:
Khanacross is only run forwards, so I can advance my timing the full 10 degrees for those.
Motorkhana sometimes requires reverse, so then I will reduce the advancing to avoid arcing. But I can also still run in a slightly higher gear (lets say 2nd) which will also avoid arcing. Plus I will have the restriction in place when in reverse. 

It sounds like for reverse I should try the middle option which I think is 3 degrees. If that doesn't work I may need to drill another set with slightly more advance.


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