Magnet dimensions

[RC-Monster Mike]

The Lehner motors have a very efficient winding technique as well, which is surely a major factor in their efficiency. The segmented magnets also are a factor (particularly at partial throttle, where our motors are most of the time - this is where the efficiency difference is noticed/realized with the segmented magnets). Of course gearing plays a major role in heat generation as well. There are tons of posts on the forum about heat that are ultimately addressed with gearing changes(some over geared, some undergeared).
The Lehner motors(19 series, 22 series, 15 series etc.) simply run much cooler in most environments. The Lehner basic series(which shares the windings with the 19 series, etc.) is also quite efficient and powerful, but there is a noticeable heat difference vs. the 1930 motor(which is about the same size). This indeed suggests and highlights the benefit of the segmented magnets, as the motors are otherwise very similar in construction.

[GriffinRU]

The Lehner basic series(which shares the windings with the 19 series, etc.) is also quite efficient and powerful, but there is a noticeable heat difference vs. the 1930 motor(which is about the same size). This indeed suggests and highlights the benefit of the segmented magnets, as the motors are otherwise very similar in construction. [/B]

It is not fair to compare efficiency of 5000Kv motor with 1000Kv.

Basic 4200 600 Watts @ 45 Amps 4200 145g
Basic 5300 700 Watts @ 55 Amps 5300 145g
Basic XL 2400 1300 Watts 60 Amps 2400 215g
Basic XL 2800 1300 Watts 72 Amps 2800 215g
Basic XL 3100 1300 Watts 80 Amps 3100 215g
Basic XL 3600 1300 Watts 97 Amps 3600 215g
Basic XL 4200 1300 Watts 110 Amps 4200 215g
Basic XL 5000 1300 Watts @ 125 Amps 5000 215g
1930/6 1200 Watts @ 30 Amps 3483 230g
1930/7 1200 Watts @ 30 Amps 2986 230g
1930/8 1200 Watts @ 30 Amps 2613 230g
1930/9 1200 Watts @ 30 Amps 2322 230g

I cannot see how you can compare them.

Artur

P.S. Data from finedesign

[RC-Monster Mike]

Who said anything about comparing a 5000Kv motor to a 1000Kv motor? My comparison was based on similar sized and Kv motors(1930/8 vs. xl2800 or a 1930/9 to an xl2400 for example). The basic xl series are labeled as 1300 watt motors, while the 1930s are labeled as 1200 watt motors. They are similar in size, similar in winding construction, but the 19 series have a segmented magnet(and run noticeably cooler as well).

[GriffinRU]

Originally posted by RC-Monster Mike
Who said anything about comparing a 5000Kv motor to a 1000Kv motor? My comparison was based on similar sized and Kv motors(1930/8 vs. xl2800 or a 1930/9 to an xl2400 for example). The basic xl series are labeled as 1300 watt motors, while the 1930s are labeled as 1200 watt motors. They are similar in size, similar in winding construction, but the 19 series have a segmented magnet(and run noticeably cooler as well).

Mike you forgot about current...
To get 1200W from xl2800 you need 72A
1300 from 1930/8 only 30A
And difference in losses associated with current would be by far greater then magnets.
Artur

P.S. Higher voltage applications more efficient always.

[Serum]

I really lost your point..

Well, like i stated before and before, in opposite to your theory, segemented magnets are BETTER in partitial load than non segmented. this is a reason for gettin less hot (higher efficiency) key is EDDY CURRENT

I lost your point in this discussion about this. I really don't quite understand the reason for this discussion?

It is not the TYPE of magnet. It is about the way the magnet is used in the rotor, which is segmented, that makes the higher end motors superior to the non segmented.

Their really is no way around it, listen, the magnet is heated up somehow. Daniel and my point of view is that it is because of the eddy currents.

1 percent of a 1500 watt setup is 15 watts of lost, so it really DOES matter. 15 watts is enough to solder with..

So based on your 'theory' it doesn't matter if you have or don't have got a segmented magnet.

Go tell the main producers of high end motors. They all use segmented magnets.

they all do use segmented magnets.

Here are some simple facts to get a high as possible efficiency;

smallest airgap possible, strongest magnet available, square or hex winding wire to use as much copper as possible, in order to replace air/isolator with copper. the highest setup voltage as possible.

Your theory/quote is wrong on the 1930/8 too buddy....

here is the thing, it has got a KV of 2615.

max rpm is 60000 (not the most efficient RPM range to begin with, but i niglect this)

60000/2615=22.94 volts.

1300 watts at 22.94 volts= 56.67A.

[Papa]

getting out the popcorn....:rolleyes:

[RC-Monster Mike]

Those numbers are meaningless, Artur(72A and 30 amp). The watt output is simply a function of voltage x amperage x efficiency. You don't necessarily need 72 amps to get the power from a 2800xl motor, nor will the 1930/8 produce 1200 watts at 30 amps unless it has serious voltage(40 volts to be exact - not counting efficiency losses!). I am talking real life here, not the information you can read and interpret many different ways.
Many people read those amp numbers and get the wrong idea. They are mostly meaningless for this discussion.
My comparison is based on a similar Kv motor, with a similar size and a similar winding construction in a similar application with the segmented magnets being the primary difference. The results are simply that in the r/c car application where partial and varying throttle is used, the segmented magnets simply perform noticeably better. The non segmented rotor may show similar efficiency on paper, but in partial load applications, it is simply not as efficient as a segmented rotor. The non segmented magnet will produce high efficiency when used at their optimum amp draw and voltage (when used in an airplane at a constant throttle, for example, there is little benefit to a segmented magnet), but as you already mentioned, the efficiency is not linear and is/can be significantly lower than their stated values in a car/truck application.

[Serum]

that power of the 1930/8 would need 1300/30=43.33 volts. at this voltage the 1930/8 would turn around with a 113000 rpm..

Needless to say, that it will die and burn..

[RC-Monster Mike]

Originally posted by Serum
that power of the 1930/8 would need 1300/30=43.33 volts. at this voltage the 1930/8 would turn around with a 113000 rpm..

Needless to say, that it will die and burn..

Exactly my point...the posted "amp values" on Chris's site are meaningless for this discussion. I used 1200 watts to get 40 volts (using the info from this post, the 1930 has a 1200watt rating vs. the 1300 watt rating of the basicxl), vs. your 43.34 volts and 1300 watts(I actually had this typed out, but changed it based on the 1200 watt posted power output already discussed in regards to this motor). The point is that the "current losses" is not relavent in this discussion.

[GriffinRU]

I would like to see someone soldering car battery posts with 15W :)

Anyone how much power requires to heat up 250g chunk of copper from 70F to 100F?

Motor specs are "meaningless" only in case if you do not know what it means.

My point here is that better or more efficient magnet (magnet is the same, but one piece v.s. segments – what I called magnets types. Maybe wrong definition.) of course better choice but lets be realistic and not be confused with something which we don’t know for sure.

As I stated before segmented or not, maximum contribution is 1%. With bigger motors it is makes perfect sense to make it segmented but with smaller ones – you know the answer.

Artur

P.S. If I am correct Finedesign CURRENT specs are for maximum efficiency but that might not correspond to maximum or rated power.

Maybe we should calm down and analyze what we have?

Actually I have a better idea, lets build dyno and check...

[Serum]

Well....

the 15 watts won't heat up the copper, but the magnet right? i thought we were talking about magnets?

Motor specs are "meaningless" only in case if you do not know what it means.

that is what i am beginning to think as well..

Who gave you this information on the 1 percent gain in efficiency?

Like Mike and I said before, it is about the efficiency in the partial load, somehow you don't seem to understand.

You don't seem to understand what this is about. 1300 watts of 30A is impossible with that 1930/8.

I don't want a needless discussion about this, but please stop spreading this inaccurate information like it's a scientific funded fact.

Now can we please get back on topic?

[Dafni]

Wow, what have I started here? Interesting, boys. But everything that matters for me are real life experiences from people who know lots of different setups. I learned myself that those "amp-calculations" are totaly useless for us.

It's also interesting to see how some discussions reveal personalities ;) Entertaining, for sure.

peace, lads
DAF

[Serum]

reveal personalities

i thought you allready knew about my darkside Daniel? ;)

Papa, would you please be so kind to share some of your popcorn?

[Papa]

Popcorn comin' your way.....;)

[Dafni]

:L: yeah, I know you Rene. Was not particulary directed at you or anybody else, just a general remark ;)

Does anybody here run one of those Aveox motors?