Do we need 6-8poles motors for 1/8 ep?

[Unsullied_Spy]

Originally Posted by littlegiant

Does a 2 pole motor accelerate or deccelerate quicker than a 4/6/8 pole motor?

2 pole motors do spool up faster, yes, but generally speaking a 4 pole motor can pull taller gearing so in a way they cancel each other out.

[littlegiant]

Originally Posted by Unsullied_Spy

2 pole motors do spool up faster, yes, but generally speaking a 4 pole motor can pull taller gearing so in a way they cancel each other out.

Thanks for answering my question.

Is the difference very obvious? Do you have any experience with 6 or 8 pole motors?

[Unsullied_Spy]

Originally Posted by littlegiant

Thanks for answering my question.

Is the difference very obvious? Do you have any experience with 6 or 8 pole motors?

No prob.

I notice a difference between 2 pole and 4 pole, yeah. It isn't huge, but if you're drag racing the 2 pole will most-likely take the cake. I love the feel of the 4 pole motors in my trucks, they spool up fast enough to flip it over (in some cases even do a standing backflip) and the torque is insane. The only 6 pole motor I've ever run was in a boat and the added torque was nice. I've since gone to a larger 2 pole motor and I'm not convinced that the bigger 2 pole motor is any better.

[_paralyzed_]

Originally Posted by superek4

My lhs was saying he is testing some boat motors 6-8poles about 1900kv can run 1hr non stop wo burning.

I am skeptical

Keep in mind boats have active cooling. People had great success with kb45's in boats, I burnt mine up in 10 mins in an e-maxx

Originally Posted by littlegiant

The brushless esc manual will often state a max rpm for 2/4/6/8 pole motor

The max rpm for a 2 pole will be higher than a 4 pole and so on....

So an eight pole may be limited to a small max rpm value depending on the esc.

every esc has an rpm limit. A 100,000 rpm limit on 2 poles will be 50,000 limit for 4 poles and 25000 for 8 poles and so on..................

[jsr]

Most of the rpm limits I've seen for multi-pole motors doesn't matter as we won't hit those rpms in our application. To answer the original question, no, we don't need 6-8 pole motors as 2-4 poles do just fine for our 1/8 trucks. But I don't think 6+ poles will be a bad thing in our application. It just takes someone to try it out. The benefits probably wouldn't be big enough to say one is better than the other. Just more options to choose from.

[florianz]

higher pole means more work for the esc, and could (but must not)cause damage to the esc (in few cases), or at least gets hotter; I have read about that problem especially with some (german) flyware-motors (multi-pole up to 8). unless it's a high quality 2 pole motor, 4 pole motors have less problems with partial load, which is typical for our cars (boats mainly have full speed).

important for the use of higher pole motors is the right timing, in general they require higher timing (depending on esc, motor). timing also can prevent from cogging. when I run my losi 4 pole xcelorin on low timing, I have a little cogging, which disappears with a bit higher timing. and I just love the torque of that motor.

I think, any new good and affordable motor and more diversity is just good for that hobby.

[snellemin]

Tashpop use to run a Mega motor in his onroad conversion. That thing was an animal. He could do a 4 wheel burnout all day long.

Here's a vid of his ride @ 35seconds into the vid

http://www.youtube.com/watch?v=_gjWzlmtJLc

[SpEEdyBL]

What is with this "higher pole motors have more torque"?

For the millionth time, that isn't true at all. If you have two rotors of the same exact size, they both have the same amount of magnetic material, and thus the same maximum magnetic force. Each pole has to be that much smaller in order for there to be that many more poles. right?

[_paralyzed_]

Originally Posted by SpEEdyBL

What is with this "higher pole motors have more torque"?

For the millionth time, that isn't true at all. If you have two rotors of the same exact size, they both have the same amount of magnetic material, and thus the same maximum magnetic force. Each pole has to be that much smaller in order for there to be that many more poles. right?

its not about the magnetic force- 4 poles fire twice as much per rotation as compared to two poles, that is why they have more torque. Like a 2 stroke versus a four stroke

[suicideneil]

Left...

what is the true advantage of multi-pole BL motors ovewr 2 poles motors, besides the handling partial load better ( I believe Pdelcast mentioned this once when the were designing the MMM motors too )?

[zeropointbug]

well a 4 pole I know can be a touch more powerful over a 2 pole for a given motor mass, and rpm.

the thing about 2 poles spooling faster, what does that even mean? I really don't know what you are talking about, I hold a 4 pole motor in my hand and WOT it hits max rpm in milliseconds, then do the same with a 2 pole, same amount of time. It makes no difference. And if there were to ever be a difference, it would be controller software, not the motor.

I think there is alot of rumors and myths that got started about this kind of stuff, one person says it, then another, pretty soon people speak it like it's the truth. no offense.

[snellemin]

You don't see dragracing(2 seconds and less) being won by 4 pole or higher motors. Some are experimenting with smaller 4 poler motors and having some success. But this is mostly due to the smaller diameter rotors.

I read this on rcgroups not too long ago, posted by murdnunoc
" high pole motor spins slower at max frequency because the motor turns a smaller amount for each pulse. A two pole motor will spin much faster for a given frequency of pulses because each pulse pulls the magnets a farther angular distance."

[_paralyzed_]

^^^^I'm willing to bet those 2 polers have twice the kv(rpm/v) as any 4 poler available.

What was stated above about frequencies may be correct, but it still comes down to kv and voltage as to how fast a motor will spin.(but not how quickly)

The "max frequency" thing has me wondering. Do we ever "max out" the pulses from an esc? Maybe BrianG or Pdelcast can answer that one. Regardless, a 2 pole would be twice as fast as a 4 pole, but at operating frequency that would be milliseconds.

So, in conclusion, maybe "on paper" per the "max frequency" theory a 2 pole would spin quicker, but in the real world human reaction is slower than the advantage so it's a wash.

Maybe snellemin's experience in the real world of r/c drag racing says it all, but the kv's would need to be the same to make an a/b comparison.

Hopefully someone with answers will chime in.

[snellemin]

I'll take my GTP for example.

With the C50 Hacker, I can accelerate faster then a 4 pole Neu counterpart. , Based on my experience topend is the same in both. The 4 poler can pull taller gearing, but at the cost of amperage. Not so good for me as I use A123 cells in 1P format.
So for equal topend under load, my C50 4000kv motor is equivalent to my Plettenberg 3000kv motor. But the Hacker can get to the finish line a bit faster. That if I don't blow tires up.

Speedruns I can go with either 2-4 pole motors as I'm limited by the 60k motor rmp. 1/10 scale motors I can push a bit further, especially with the Lehner basic, LT motors, and c40 hackers.

[_paralyzed_]

did you try a 4000kv neu?

gotta be apple 2 apple........