Brushless Motor Brands
 

Hello,

I'm sorry for what will to many of you be a basic post. For two years I've raced a brushless E-Maxx very competitively. I've done alright and I thought I knew everything one needs to know about brushless but today I feel like I was only really understanding a fraction of what I should know.

I know that during the heat of summer, my motor temps were a bit high and thus I figured that during my winter rebuild, I may replace my motor...a quick look at the RC Monster Brushless motor page is what has me questioning my grasp of this tech. I've always run Feigao motors, a 9L or 10L on 14 cells. Someone suggested maybe looking at a 7XL or 8XL as a cooler alternative. I found that RC Monster is moving to BK motors - that's cool. I've read they are similar to the Feigao's but with slightly better bearings. The I clicked on Lehner...

I've spared no expense with my E-Maxx. I purchased my brushless based on another guy running at my track. He gave me the part nums and I ordered it. I've not really thought much about it till now. What are these Lehner motors? I generally believe that you get what you pay for...the Lehner 1940/1930 motors are 2.5x the cost of the Feigao/BK motors - are they that much better? Why?

Then there are the XL Lehner motors...I assume the number is KVolts...so XL3100 is 3,100 RPM per volt.

Why are the XL's so much less $ than the 1940/1930?

Which is the ultimate Brushless Motor on 14 cells? Why? I guess one more mystery is once you know KV, what is the difference between say a 2400KV Feigao vs BK vs Lehner 1940 vs Lehner 1930 vs XL2400 (if one existed).

Aside from heat issues, I've been quite happy with my 10L & 9L motors. Now that I've seen there are other motors for much more $ I can't help but wonder why and what I'm missing.

Hopefully some of you Brushless-Whizzes out there can shed some light on this for me.

Thanks in advance.

DM

well the advantages to the xl's are the longer can which will provide much more torque than your 9 and 10l which will allow you to gear up thus run a lower kv motor to draw less amps and get better runtime. the lehner 19 and 22 series motors are motor expensive because of higher quality, tighter tolerances and segmented magnets which will give you more power and higher efficiency which in turn give more runtime. on 14 cells, runtime not being a issue i would go with a 6xl for shear speed but if runtime was an issue i would go with a 9xl which you can gear alot higher to have almost the same overall power but have more runtime. but yes, the 6xl will give you more speed. i would personally stay away from the lehner xl basics because they wont have as much torque as your 9 or 10L and will run somewhat hot.

The lehener 1930 and 1940 motors are great. They run cooler and more efficent than a feigao. I was going to race a 1930 10t against a feigao 8L. They seemed about the same speed and power. had same gearing on the trucks but the 8L was running 14 cells to my 12. I was getting about 5 min(17min total) more run time out of it. The windings are built out of different material in the motors to. I posted a pic in the magnet dimesions thread.
To me for the money the lehner rocks in the 19 and 22 series.

Thanks very much guys..the fog is lifting...I don't see this "22 series" listed anywhere on the site - are these "E-Maxx" size motors? Also, what is the difference between the 1930 and 1940 motors?

Thank you,

DM

the 22 series motors are very big, and would almost definately require a larger motor mount. The 1940 is slightly longer than the 1930, hence it has slightly more torque but a lower kv rating.

I run a lehner BASIC XL2000 on 18cells, and although it is very powerful it tends to run slightly hot. Personally I think that the bk wanderer motors are the best in terms of value for money. Personally, if I was running a 14cells set-up I would go for an wanderer 8XL, or if I had the money a 1940 in the 2400kv range (a 1930 will run hotter than a 1940)

a 1930 10t qith 13 cells on it runs 115 f.

Ok, something here isn't adding up...if you check the "charts" the 1930/10 is 2090 k/v and the Feigao 8L is 3072 k/v. Do the math and you should see a theoretical RPM of 51609 for the 8L vs 30096 RPM for the 1930/10 - now if the gearing was the same I don't see how the 1930 could be about the same speed and power. Maybe the 1930 was quicker off the line but once moving the 8L should be much faster.

Oddly I want the 1930 to be a better choice here, I just wonder if you can explain why...

Thanks,

the 1930 are rated under load. The 8l are done not under load. I wouldn't think it was that big of difference. I own one and think that they under rate the kv.

Got it...thank you for that info...if the 1930/10 is like an 8L i can't imagine how insane a 7 or 8 would be...

DM

I have the 1930/8 and the 1940/8 in different trucks. they both are absolutely awesome motors. In a full 5 minute race with 5s Lipo, the little 1930 was around 150 degrees(pretty warm outside, too). It is similar in size to the Feigao "s" motor, too, so this temp is a testament to the greater efficiency of the high end Lehner motors. I don't have much of a preference between the two, actually, but a heavy truck looking to maximize runtime and minimize temps should consider the 1940 motors the "cream of the crop" IMO.

Yeah their efficiency on partitial load is much better too. (they get less hot because of this too)

Still, there should be a difference between the 1930 10t and the feigao 8l. To compare kv's of lehner motors vs. feigao motors, multiply the feigao kv by .9 to get the lehner equivalent. Kv drop under a typical load is actually quite small and you would need a huge load to make a 3000kv motor to drop to 2000 kv under a load. Rpm drop per amp is no-load kv times motor resistance. It doesn't matter how many volts are applied, rpm drop per amp is a constant. Lets take the 8l for example and say your running it on 12 cells. 3072*.0076 = 23.3 rpm drop per amp. In the worst case senario, let say the motor is drawing 60 amps. At 14.4 volts the motor is still pumping 2974 kv under that load. Voltage drop of the batteries will will make the motor spin slower. The person with the lehner 1930 10t probably had better batteries.

Well if one motor is drawing 60 amps and the other is drawing 30 amps. The voltage drop is going to be less and the rpm will be higher. Then you have to figure in efficence and the lehner beats the feigao out on that. Now for you figures I don't think is right. A 7xl wanderer is 2145 and the feigao is 2382. That is a bigger difference than you posted. the 8l is feigao 3072 and the wanderer is 2765.

rpm/volt is constant(load rated). It doesn't change. Only the voltage will actually change(voltage drop=rpm drop). The 8L is similar in loaded rpms to the 2800xl Lehner motor, actually. Given the same gearing and setup, it will for sure be faster than a 1930/10 motor(unless the amp draw lowers the voltage to offset the rpm difference, but this would require pretty crappy batteries)