Search found 202 matches

by thepronghorn
Apr 02 2019 4:04pm
Forum: Motor Technology
Topic: Need help with motor contactor!
Replies: 2
Views: 137

Re: Need help with motor contactor!

The 12V rating for that contactor is for the coil. It looks like the contactor itself is rated for 900VDC which should be plenty for your 400VDC battery.
by thepronghorn
Mar 27 2019 4:54pm
Forum: Motor Technology
Topic: Serious FOCer (84V VESC 6 based controller)
Replies: 58
Views: 3159

Re: Serious FOCer (84V VESC 6 based controller)

So I take it looking at your renders there are no bus bars in this design, you'll be using direct connection at each FET set to positive and ground? Yes this is the case. Also the legs of the FETs will be bent to where each cable comes in to the board to help make a solid connection. This eliminate...
by thepronghorn
Feb 28 2019 4:11pm
Forum: Motor Technology
Topic: Air gap, magnet shape, and voltage questions
Replies: 12
Views: 645

Re: Air gap, magnet shape, and voltage questions

Simple models suggest that a motor is most efficient when its copper losses and iron losses are equal. Roughly, copper losses are proportional to square of current while iron losses are proportional to square of speed. I'm not exactly sure how your hydraulic load cell works, but perhaps you are runn...
by thepronghorn
Feb 25 2019 1:25pm
Forum: Motor Technology
Topic: Why never see metal cast around wound stators?
Replies: 67
Views: 2332

Re: Why never see metal cast around wound stators?

I think it's an interesting idea. Are you trying to increase heat conduction from the windings to the inner core of the stator or to the end caps of the motor? Fwiw, I don't think zinc cast inside the stator core where the windings are will significantly hurt eddy or hysteresis losses. As has been p...
by thepronghorn
Jan 23 2019 3:11pm
Forum: E-vents
Topic: Sea Otter Classic 2019, April 11-14, Monterey California
Replies: 15
Views: 850

Re: Sea Otter Classic 2019, April 11-14, Monterrey California

only bikes operated by the following systems may race: Bosch, Brose, Shimano, or Yamaha
:(
by thepronghorn
Nov 15 2018 9:44pm
Forum: E-Bike Build Threads / Photos & Video
Topic: Neu 8057 6kW left hand drive hardtail with vesc and encoder
Replies: 59
Views: 5193

Re: Neu 8057 6kW left hand drive hardtail with vesc and encoder

Can you go into more detail or show some more pictures of your bottom bracket and mounting plate setup? I had the same idea of mounting a motor in front of the bottom bracket and driving the rear wheel directly on the left side. Specifically, it looks like you are running an ISIS bottom bracket? Is ...
by thepronghorn
Oct 29 2018 4:02pm
Forum: Electric Aircraft
Topic: practical range
Replies: 7
Views: 735

Re: practical range

Beautiful picture. The Tetons are one of my favorite national parks.
by thepronghorn
Oct 19 2018 1:41pm
Forum: E-Bike Non-hub Motor Drives
Topic: My RC Mid Drive with Single Stage Reduction
Replies: 225
Views: 12889

Re: My RC Mid Drive with Single Stage Reduction

Would using a 60kV motor such as this one: https://alienpowersystem.com/shop/brushless-motors/aps-5065-outrunner-brushless-motor-60kv-1800w/ potentially open up higher voltages or simpler reductions? Nope, changing Kv does nothing to change a motor's torque capability, it only changes the voltage/c...
by thepronghorn
Aug 29 2018 2:44pm
Forum: E-Bike Technical
Topic: Kv * turns = constant?
Replies: 10
Views: 564

Re: Kv * turns = constant?

Markz, ProxRB is not messing up the turn count thing. He's just recognizing that spinning faster and gearing down to the same speed results in more torque capability. ProxRB, you don't necessarily need to increase Kv to increase speed. You could also increase your battery voltage. Besides being able...
by thepronghorn
Aug 27 2018 1:38pm
Forum: E-Bike Technical
Topic: Kv * turns = constant?
Replies: 10
Views: 564

Re: Kv * turns = constant?

First, I'll define my variables just for clarity's sake. Kv: rpm/volt Kt: torque/amp Rm: motor phase resistance P: power I: current V: voltage w: angular velocity T: torque Yes Kv is proportional to the inverse of turns. A 200Kv, 4 turn motor will be 100Kv if wound with 8 turns. Rm is proportional t...
by thepronghorn
Aug 07 2018 4:25pm
Forum: Motor Technology
Topic: Minimising rotor losses
Replies: 94
Views: 4120

Re: Minimising rotor losses

larsb wrote:
Aug 07 2018 3:44pm
This paper explained a lot to me on the harmonic losses, when they occur and some of the compromises in motor design:
Slot pole Combinations Choice for Concentrated Multiphase Machines.pdf
Very good read. Thanks for posting that!
by thepronghorn
Jul 26 2018 5:53pm
Forum: Motor Technology
Topic: Minimising rotor losses
Replies: 94
Views: 4120

Re: Revolt RV-series motor review and comparisons

Lol I spent like four hours reading and writing this post, so hopefully we can get this useful conversation moved to its own topic. I have read all the posts and links in this thread, and I think we all agree on a lot of things and disagree on just one thing. Agreements Different motors have differe...
by thepronghorn
Jul 25 2018 6:06pm
Forum: Motor Technology
Topic: Minimising rotor losses
Replies: 94
Views: 4120

Re: Revolt RV-series motor review and comparisons

My comments and conclusions from this article: "Reducing PM Eddy Current Rotor Losses by Partial Magnet and Rotor Yoke Segmentation" Regarding magnet segmentation right up front this article says this which basically maens magnet segmentation is not ever going to be something any manufacturer will ...
by thepronghorn
Jul 20 2018 12:37pm
Forum: Motor Technology
Topic: Minimising rotor losses
Replies: 94
Views: 4120

Re: Revolt RV-series motor review and comparisons

"..It's actually increased stator hysteresis losses not stator eddy losses from higher electrical frequency." @thepronghorn:As the frequency is one of the factors in below formula i doubt that you are correct. (It's from Wikipedia). Eddy current losses are proportional to the square of the frequenc...
by thepronghorn
Jul 19 2018 1:46pm
Forum: Motor Technology
Topic: Minimising rotor losses
Replies: 94
Views: 4120

Re: Revolt RV-series motor review and comparisons

... Of course that means you have a motor with 200 poles to eliminate the eddy currents. Clearly there has to be a middle ground between ridiculous magnet counts and minimizing eddy losses. I think this may be the reason why hubs and outrunners have lots of magnets. This may be the place where eddy...
by thepronghorn
Jul 18 2018 3:29pm
Forum: E-Bike Non-hub Motor Drives
Topic: RC motor on swingarm
Replies: 6
Views: 613

Re: RC motor on swingarm

I = 0.5*M*R^2 Inertia is directly proportional to mass but proportional to the square of radius, so moving mass closer to the pivot point will decrease inertia a lot. Your example of replacing a 4kg hub motor with 2kg of motor at let's say 1/2 the radius results in (1/2 the mass)*(1/2 the radius)^2 ...
by thepronghorn
Jul 18 2018 11:57am
Forum: E-Bike Non-hub Motor Drives
Topic: Castle LINK programming kit - is it necessary/worthwhile with CA V3?
Replies: 11
Views: 522

Re: Castle LINK programming kit - is it necessary/worthwhile with CA V3?

Yes definitely get the Castle Link. The CC ESC needs some settings adjusted out of the box.
by thepronghorn
Jul 12 2018 6:35pm
Forum: E-Bike Non-hub Motor Drives
Topic: Dave's 80:1 RC mid drive kit build log
Replies: 1374
Views: 170190

Re: Dave's 80:1 RC mid drive kit build log

Drive unit weight: 7.5lbs Dimensions: 100mm diameter, 120mm length Engine: Neutronics 3215, 225kV Controller: Castle Talon 120, custom mount/heatsink, QS-8 main battery connect Performance (calculated w/ 120A phase): 135ft-lbs crankset torque 400RPM crankset 48t cog: 216ft-lbs wheel torque, 21mph 4...
by thepronghorn
Jul 05 2018 7:03pm
Forum: General Discussion
Topic: Why Is 18650 So Popular?
Replies: 11
Views: 742

Re: Why Is 18650 So Popular?

I'd say they still sell 1000+ tool packs for every Tesla that gets sold. Most of the tool packs aren't sold to average consumers for occasional use, they're sold to trades people that burn through these packs at a rate of several per year. Not sure about that... 2000 Model S and X last week = 16 mi...
by thepronghorn
Jul 05 2018 5:30pm
Forum: Motor Technology
Topic: Revolt RV-series motor review and comparisons
Replies: 191
Views: 10357

Re: Revolt RV-series motor review and comparisons

Generally it's easiest to measure the width of 10 or 20 lams. The specs we need to characterize the performance of a motor are phase resistance, speed constant (aka Kv, rpm/volt is a common unit), and losses at no load at two different voltages. The page below discusses how to measure them all. http...
by thepronghorn
Jul 05 2018 3:26pm
Forum: Motor Technology
Topic: Revolt RV-series motor review and comparisons
Replies: 191
Views: 10357

Re: Revolt RV-series motor review and comparisons

Like madin88 said, measure the Rm, Kv, and no load losses at two different voltages, and then we will be able to compare these two motors performance wise (inductance would be nice as well for an indicator of the "controllability" of the motor). You have already covered their mechanical design fairl...
by thepronghorn
Jun 29 2018 8:27pm
Forum: E-Bike Build Threads / Photos & Video
Topic: My Sun Trip Bike, Back to Back Tandem Trike with Rowing Generator, Pedals, +Solar
Replies: 334
Views: 31323

Re: My Sun Trip Bike, Back to Back Tandem Trike with Rowing Generator, Pedals, +Solar

Did anyone else spot the super soaker water squirt gun strapped to the trike? What's it for?
by thepronghorn
Jun 27 2018 2:29pm
Forum: Battery Technology
Topic: DC/DC converter 72v to 36v?
Replies: 5
Views: 315

Re: DC/DC converter 72v to 36v?

Many 36V controllers will not appreciate being fed 84V from a full 72V pack. 63V rated capacitors are pretty common in them. Do some research first. .... I think you're talking to me here? That's why I said to use a 72V controller. If you're talking about my last sentence, I guess I should clarify ...