Motor heat

[keithbradley]

Keith. I am in the same mind set as Doug. One thing to remember is we set-up our boats for Oval not SAW. They run from 2- 4 minutes all out. I may be off here but there is a difference in Oval and SAW when it comes to can size. Oval we like more mass to dissipate heat. SAW from my observations like high RPM. so smaller can size and low winds.

Just to clarify, I wasn't implying that doug was doing anything wrong, just agreeing with him that he is indeed using large motors that are capable of far more than he demands, and I believe that is his intention.

I don't really agree with the assessment of SAW vs. oval, but either way I didn't mean to imply disagreement, just adding to the conversation.
For the record, I run all out too. Outside of sanctioned SAW events, I run hard. I'm not a one pass and bring it in guy.

[T.S.Davis]

For the record too, TP makes a great motor. Especially for the price.

Sean, sorry man. Feels that way too. Only one of us wont be moving into a van down by the river.

You know where we live. Stop by any time.

[DPeterson]

Interesting comparisons between SAW and OVAL. I too would lean toward small can high rpm for SAW and large can normal rpm for OVAL. I own a German SAW record and a US OVAL record. Both in the days of NIMH's. In those days the heat issue was with cells. Cooked a bran new expensive 12 cell nimh pack getting the OVAL record. Not much heat in the motor. Along came 2P Lipo and the heat instantly went towards the motor and esc. Had a couple multi thousand dollar days learning this.

Also interesting is that there is widespread knowledge that exists in the Hobby to control heat and or premature melt down of a motor and we don't utilize it.

Doug

[keithbradley]

My 8s and 10s boats run 3040, 3060 and 3080 motors.

That's not unreasonable, although I can't think of many situations where I would run a 3080 on 8s...doesn't mean it's not right for you, I just can't think of any application I would use it in. I set up my 73" 50lb Mystic with twin 3080s on 14s and if anything the 3080s were overkill, but an awesome display of power nonetheless.

It should be noted that I run almost exclusively twin powered boats. When I said I use 2260s in some 8-10s boats, this would only be for certain applications. I WOULD run one in a (smaller) 8-10s single motor boat too (If I for some reason wanted to build a single), but not in something large/heavy/wet. For example, the big, wide 40 something inch cats you guys would run in T-cat require a good amount of power to move and I wouldn't choose a single 2260 in one of those. My HPR 135 was I think an easier hull to push and I ran twin 3040s in that, although twin 2260s would be quite capable also.

So, I totally understand why you would run a 30 series motor in many HV applications.

[keithbradley]

Interesting comparisons between SAW and OVAL. I too would lean toward small can high rpm for SAW and large can normal rpm for OVAL. I own a German SAW record and a US OVAL record. Both in the days of NIMH's. In those days the heat issue was with cells. Cooked a bran new expensive 12 cell nimh pack getting the OVAL record. Not much heat in the motor. Along came 2P Lipo and the heat instantly went towards the motor and esc. Had a couple multi thousand dollar days learning this.

Also interesting is that there is widespread knowledge that exists in the Hobby to control heat and or premature melt down of a motor and we don't utilize it.

Doug

I understand your logic in using a larger motor than needed for oval, but I don't see what is to be gained by using a smaller can for a SAW application. Perhaps you won't see the same cumulative heat build up because runs are short, but you will see heat generated much faster, and in an overloaded motor current spikes possibly much higher than a proper motor would produce. In experimental setups I've seen well over 1000A spikes on MGM logs. These are very short spikes that occur between the poles when a motor is overloaded; short enough that most logging ESCs and loggers don't even pick them up. They are, however, still quite potentially damaging to both the motor and ESC.

It's almost an absolute that a SAW boat will run comparatively higher RPM, but again I don't see why this would lead you to run a smaller, less powerful motor. If anything I would suggest a larger motor as power demands will be substantially higher.

FYI... If you don't agree, that's fine; I'm interested in hearing why. I enjoy intelligent discussion and think everyone usually benefits from it.

**Also, I think the motor you choose has a noteworthy effect on the longevity of your ESC as well. There is a significant difference between running a 2-pole Lehner motor and a 4-6 pole TP motor, for example.

[Peter A]

**Also, I think the motor you choose has a noteworthy effect on the longevity of your ESC as well. There is a significant difference between running a 2-pole Lehner motor and a 4-6 pole TP motor, for example.

Can you explain, simply due to my lack of knowing here. Are you saying that 2 pole motors are better on esc's than 4 or 6, or Lehners generally and why?

[photohoward1]

Keith would you agree that 2 pole Motors are easier on the controllers?

[keithbradley]

Yes. I think a large portion of ESC failures with 4 pole/6 pole motors are a result of stress from inaccurate commutating due to weak BEMF and/or higher frequency.

[keithbradley]

Keith would you agree that 2 pole Motors are easier on the controllers?

I would agree that Lehner 2 pole motors are.
Feigao is however not on my friends list.

[ray schrauwen]

I would agree that Lehner 2 pole motors are.
Feigao is however not on my friends list.

You got burned by a Feigao huh? Or the Feigao got burned...

Did you put a pair in one of those little twin cats or something? I'm curious on this...

Hacker USA is gone, they were nice but, quite the price jump from Feigao. Might as well go Lehner then.

I forgot over time that 2 pole motors are easier on esc's. I got all goofy when all the cheap 4 pole motors came out.

[DPeterson]

Keith - The preference for a small can for saws would only be an assumption on my part today. I have put zero thought into it. I guess maybe because of the weight savings?

I took all my Lehners out of storage yesterday to look at them again. I miss them. Can't believe I am even remotely involved in those other ones.

It looks to me that any and all of the lower cost 4 poles are way better quality than any of the 6 poles. Is there such a thing as a 2 pole low cost motor?

I always wondered about the relationship between esc's and the various motor poles. More info here would be most beneficial.

Doug

[ray schrauwen]

1. It looks to me that any and all of the lower cost 4 poles are way better quality than any of the 6 poles. 2. Is there such a thing as a 2 pole low cost motor?


Doug

1. TFL makes a 6 pole motor. Are they not close to TP Power quality? I ran an SSS in my 40" mono and it never broke a sweat for 3rd in Q-mono and Q-offshore. Steve sold out dang quick on the SSS 4074 2200kv 6 pole motors....??

2. Cheapada chepo right here: http://www.hobbyking.com/hobbyking/s...er_2200kv.html

[Darin Jordan]

If you start mixing pole count, you might as well bag it and just run P... Definitely no longer "Limited".

And, just to be realistic about things, you've already created a one motor spec class. By your own admission and "on water testing", plus my own experience with FE motors, the current motors have been made obsolete with this new motor choice.

Might want to just keep it at the TP motor for now.

[ray schrauwen]

Lets just see what happens in the middle of summer. Heat does strange things...

If you start mixing pole count, you might as well bag it and just run P... Definitely no longer "Limited".

And, just to be realistic about things, you've already created a one motor spec class. By your own admission and "on water testing", plus my own experience with FE motors, the current motors have been made obsolete with this new motor choice.

Might want to just keep it at the TP motor for now.

[Jeff]

If you start mixing pole count, you might as well bag it and just run P... Definitely no longer "Limited".

And, just to be realistic about things, you've already created a one motor spec class. By your own admission and "on water testing", plus my own experience with FE motors, the current motors have been made obsolete with this new motor choice.

Might want to just keep it at the TP motor for now.

And yet another thread derailer. Thread is motor heat not spec motor rules. There is already a thread about that.

What is it with you guy's lately?