Lehner Power Ratings Help
 

So what's up with Lehner rating their motors at the same power at the same amperage for all of the winds in a series? Like this:

1940/6 - 1400W @ 50A
1940/7 - 1400W @ 50A
1940/8 - 1400W @ 50A

And so on down the line. It would seem like this contradicts the properties of electricity. You need more voltage to put the same amperage through a higher impedance. And thus with a constant amperage there would be an increase in power output as the impedance increased. I want to upgrade my Rustler to a 1940, but, I really don't want to have to cram an 8s LiPo in there too! Not to mention a controller that can handle the voltage. Help?

Maybe the power rating is how much the motor can dissipate and the current is the continuous amperage of the wires themselves?

Or maybe someone simply got carried away with the cut-n-paste feature. :)

You're right though, if those figures mean what they say, each motor has a resistance of 0.56ohms. To get 50A and 1400w, you'd need 28v...

I think your right about the cut-and-paste thing. I've been reading lots of posts on this forum about people running 1940/50 series motors at 5s or 6s and I'm thinking to myself: "They can't be getting full power from that motor! Can they?".

You're right, we usually aren't getting the full power from these motors.

Each motor version (# turns) in a series, such as 1950 has the same peak power that is able to be extracted from them. It's just a matter of what configuration you want to run, higher voltage/lower amperage requirements, or lower voltage/higher amperage requirements. However, the higher voltage/higher turn setups USUALLY can extract a little more power than vise-a-versa, because of higher resistance losses, and hence more efficient.

One thing I notice with the Lehner motors is that the lower turn motors have great efficiency at higher torque's. Whereas, the higher turn motors have great efficiency at lower torque's, and slightly less efficiency than lower turn motors at higher torque's (a couple % points); BUT, overall the rpm range, they have a better average efficiency. It kinda depends on the application really. :030:

Keep in mind, the motor can only produce as much power as the batteries can handle. 1400 watts isn't possible without batteries that can deliver it. Thats not something most batteries can do. Besides, with good enough batteries, you can get over 1400 watts out of the motors, even though they may only be rated for 1400. Make sense? Just keep in mind that its only a rating, or guideline.

Keep in mind that most of this stuff is over my head, but I read someplace that the amp draw ratings of a motor are supposed to be the maximum constant draw of the motor when you apply the maximum voltage to the motor. The maximum voltage is the highest voltage that you can apply without exceeding the maximum rpms. The wattage rating of the motor, from what I understand, is what the motor is capable of producing with a capable power supply.

Well you can get a minimum of 50A from a 20/25C 2480mAh LiPo. So That shouldn't be an issue unless you are poor and would rather eat dinner than buy new batteries. And I'm sure you could put tons more power into them if you wanted but I'd rather not blow a $300 motor.

I always figured the wattage ratings are just a very rough guidline to help you choose a motor from the range,not a measured specification in any way.the lehner motors can pull an awful lot more peak power than those figures anyway.

Yeah I figured it was a constant power rating, but it's that constant amperage rating that is confusing to me. I want to get the maximum power from the motor, so if necessary I will cram 8s' worth of LiPo into my Rustler.

Yeah,i see what you mean,i don't know where the @ 50A comes from,where does it say that?

btw,you don't want 8s lipos in a rustler,with a stadium truck and brushless,power is simply not a limiting factor regarding speed,eg you will have issues to work out with just a 1930/8 on 4s,like keeping it in one piece and on the ground,aerodynamically a stadium truck is already an aeroplane at those speeds.

Well I have a Novak HV 6.5 in it now on 4s LiPo and I would say it does an easy 40 MpH with 19/87 gears, maybe 45. And with 1" of ground clearance I have no problem with control. I mean it doesn't flip over it just spins out repeatedly if I corner to hard. How much power would you actually get from that 1930/8 on 4s? The HV puts out 400W already. I got the motor information off of the Fine Design page. Yep I said the "F" word.

Tons,trust me.more than a rustler that you could still call a rustler can use.With smaller systems than that,the power available is already not a limiting factor in any way with regards to speed or acceleration.you need wings front and back and you need to be prepared to break it alot when you venture that far above 60mph with a lightweight stadium truck,they produce a lot of lift.60mph already looks quite quick with one but is pretty easy to achieve.I use a 1920/10 on 4s in a xxxt sometimes and that will hit over 60mph,drop in a 1930/8 in the same truck and you start to wish it had less torque.
This thread is very worth checking out if you haven't already,http://www.rc-monster.com/forum/showthread.php?t=6165,impressive stuff for a little buggy that's meant to go 20mph round an offroad track.

Did I mention it's primarily aluminum, I have an RCM-RC chassis, and I turned the transmission around? It weighs almost 8 pounds with everything. I need new pictures...

Is that chassis longer than stock?that would help a lot too if you're looking to hit some big numbers.

The lower the KV, the less current a motor can handle (since it's made for higher voltages and has got a higher internal resistance)

the motors with different KV's from the same serie take different currents. (lower KV, higher current) their 40A rating is simple rubbish.

It would also only draw so much current, no just current handling.

I think if you want some nice power ratings, then check out Lehner's motor power examples page. Quite a few power setups, most of their winds, most voltage setups, etc.

They have one page their where the 3060 motor is putting out 15,000 watts @ something like 94%, and peak efficiency is 95% somewhere around 10,000 watts. CRAZY.

I am going to be getting their 3080 motor for a project of mine soon, probably a 3080/20 turn at 52.8 volts.

Your 3080 project sounds like it would be for some type of personal conveyance, such as a bike or something. I thought about experimenting with things like that, but my disposable income is not that high...

Brian, must have seen where he posted what he was gonna do with it, no?

I guess not... :dft001:

Brian, have you heard about the Segway 'concept centaur'? :eek:

I am waiting for a reply back from Lehner email... to see if it has enough 'mass' to the motor to power it(duty cycle). But seeing as it's so efficient, it should be no prob with water cooling.

I plan on using A123 batts for a 52.8volts, with 23Ah cap (16s10p). But i asked them if they knew of a higher voltage controller (Jazz Power 63v) that I could use with say ~100 volts. The whole thing should weight between 100 - 120 lbs, maybe more. I want to use maybe 8,000 watts from the 3080, again maybe more. :005:

It's a fairly simple build I think...

160 A123's!? You plan on building a custom pack yourself? If so, thats gonna be alot of soldering. :eek:

ZPB: Yeah, I saw that a while back. I figured your project would be something like that. My project wouldn't be that extensive (having the gyros so it controls somewhat like the segway); just BL drive. I figure a mountain bike or something along those lines would be good too, and light.

Squee: And can you imagine the balancer harness?! :dft002: :005:

Yup, and that's an undertaking I'm willing to take... :027: :002: What have I got myself into...

Brian, my build of the centaur is a much simpler version than Segway's, mine will NOT have gyros and such, and indeed 6? CPU's?

Also, I plan to use internal BMS (battery managment system), you don't use external balancer connectors.... LOL, imagine that, 16 cell balancer connector.

Anyways, it is a 27,600 watt (true) continuous pack, with voltage droop (2.5v/cell), and 30C cont. factored in. :018:

It will be something! Hopefully it can wheelie on demand! :017:

Cheers

What do you plan to use for a controller?

I think he is gonna use the Jazz 63V.

Yes, either the Jazz Power 63v (which is very well built BTW), or I'm going to use dual 2500 watt hub motors meant for electric moped (scooter). That will get rid of gearbox, cleaner setup, and the controller might be more durable, and up for the challenge. I'll see... should be pretty cool though.

I know i talked you into that esc; But it has got no proportional brake, and i think these are a must on these gyro controlled things..

no no, I'm not using any gyro controlling, i said that in a previous post. Really, how would I even go about doing that?! :032: :030: :024:

Yah, was it you Serum that mentioned this esc? I definatly won't be using motor breaking, i'll be using high end mountain bike disc brakes, very powerful, and precise.

I would like to use the Jazz Power in my next brushless setup, and run like 12s LiPo or something, with a 20+ turn 1940/50. That would be cool... literally

BrianG, You were correct with your first statement. No need for second.

It would be incorrect to report max current at max. power.
Maximum Power and Maximum Current do not exist at the same time!

Check my program and lots of things will become clear...

holy crap the 7Xl has crappy efficiency... :mad:1

I does put things into perspective, comparing a 1940 with 94+% peak eff., and 92% peak power eff.

I'm afraid to fire up my 7Xl now.... I still don't have my truck built (parts arrive mid-this-week)

Griffin: That makes sense. It's just too bad that information wasn't explained better at the various motor sites. I bet lots of people are making incorrect assumptions about the ratings of these motors.

ZPB: Just because the 7XL isn't as efficient as a higher quality motor, it's still better than a brushed motor. Besides, you pay a hefty sum for the good stuff. I guess it's up to the end user if a high-end motor is worth about triple the price for ~10% difference in efficiency. If you plan to run hard all day long with no breaks in between, then maybe you'd be better off with a high-end motor. For typical R/Cers, the 7XL is perfectly fine. I just give my 10XL 5-10 minute breaks between runs.

Yah, that's true... it's really a heat matter.

Seeing as how much current my 7XL will be able to draw, my big@$$ heatsink :005: should sure come in handy. I have a plan for a really good layout on the FLM chassis, I just hope there is the room for it.

flm chassis? your own idea is gone?

Frick...yah. :024: It was going to cost to much, I don't have enough money to spare right now; it was over $600 for it.

BUT, rest assured, I will get something machined someday. I would like to make it a better design, one that will take the tranny, and slipperential.

Maybe something for the Revo instead?