ES DIY Motor Challenge

[liveforphysics]

For specific power, even some dirt cheap RC motors are in the 4.6kw/Kg range. This is with a KV of 130, which easily enables the reduction to be accomplished in a single stage reduction. My own bike is an example of this.

Your motor isn't made to direct drive a rear wheel, you must also incur the losses from power transmission to the rear wheel. The drive train loss between a single stage of 4:1 or a single stage of 10:1 is in the fractional percent area. This is way more than compensated by the broad range of >90% efficiency from the RC motor vs the much heavier and lower efficiency alternator motors.

[liveforphysics]

But this contest isn't about specific power. We thought about that, and it would come down to whom ever was willing to spend the money for the greatest ceramic bearing technology, and the windings would be the solid milled bar 1/2 turn type, and the KV numbers would likely hit the 5 digit range. It would end up with motors that have incredible specific power, but minimal practical use for an EV.

This is why our contest is about specific torque. I'm shooting for my motor to have a KV in the 30's. It will be as near to silent as any air cooled motor can be, and it will work great for driving the wheel of a bicycle with a simple single stage reduction.

I assure you we are making motors as practical as any for EV use.


If you can come up with something under 3Kg, it would be great to have you enter. Nothing else drives a point home like winning.

[Miles]

Randy,

I do understand about drive losses, thanks. I've structured the challenge in this way to allow for a wide variety of motor types/sizes, without it getting too complicated. It's a motor challenge thread. Others seem to get the idea, I don't know why you have such a problem with it....

Why are you worrying about the higher speed motors that, according to you, won't be able to generate the specific torque required?

Entering an optimised PMA motor in the Challenge would be the best way to demonstrate your competence.

I'm not going to allow this topic to degenerate into another one of your soapbox threads.... Put up or shut up

[enoob]

Please tell is how to compare over all performance of a ebike motor/drive system short of running a ebike wheel on a calibrated dyno
How will this "motor challenge" be judged?
By only rating a motor will not give you the overall performance of the drive system in all conditions.
Quietness and reliability has also been overlooked IMO.

Have you read this entire thread ?

DYNO testing of the motor . must make specified torque

performance of the drive system is not the contested . despite the wonders of a dual drive setup does every ebike HAVE to run the same drive. ? i may choose to have the winning motor run in a friction drive setup on the back tire with my drill as a backup.

i dont care about quietness, i want loud, and reliability is something that comes with practical use to discover weak points and reworking to make better. was your first version of an altermotor the one we see now ? or was there a magnet issue that got addressed ? i seem to have read something about that.

[bigmoose]

This is a GREAT thread and a GREAT IDEA! Just like the Centennial Challenges the big guys do... all we need is "someone" to pony up a $1,000,000 prize for the winner. **2

I was wondering if the person entering the motor should supply his/her controller of choice with it when it goes in for dyno testing? Perhaps also some standard battery voltages should be identified for the test so the tester/judge has a chance at having the right power supply.

PS: I'll throw in $20 bucks towards the top prize. This should be great fun to watch!

[Thud]

On Topic:

Laser tach finally arived! (slow boat from China has graphic meaning to me now!)
The Dyno patterns are in proccess & I am looking foward to showing it off.

off topic:
Previously, my favorite word to say aloud was: "phenominal" (with the tricky p-h on the front, it just feels good to say it!) but lately I have been evaluating a new word.
The new word on the top of the list is "Dynomometer"
It has an additional sylible & a hard consanent on the end that gives it "phenominal" closure.

Try it, I think you will enjoy it far more than the previous thread drift....
Dynomometer, Dynomometer, Dynomometer,

(20 bucks will get a lot of kudos!!! too generous bigmoose, Thank you Very much)

[bigmoose]

Thanks Thud!

I'll think with you on the dyno if that is OK? What max torque & max RPM are you going to design to?

[Toorbough ULL-Zeveigh]

Dy-No-Mo-MOMETER!!

JimmieWalker2.jpg (9.01 KiB) Viewed 780 times

[jscoot]

John,

Like I said, larger motors do have an advantage. That's the reason for the 3kg limit. This is the non-hub motor forum

0.5kg to 3kg should be the range that most people want to work within?

A important aspect of having a 5 kg limit would be to enable people to take advantage of reasonable priced high quality magnets, rotors, stators, and housing with a rather large selection to configure a optimal kv and efficiency for a project that most anyone can get involved with to make a powerful bike motor that will progress to the most economical and easiest way to get there high performance ebike on the road. This type of building block system can be tweaked in many ways including stamped silicon laminations and custom thin multi wire stator windings to reduce end turns and have more copper on the stator. Several rotor and magnet arrangements are available for less than it would cost to just to purchase the magnets on your own. If you are thinking of how to get the most efficient bang for the buck the easiest way with tested reliability, this is defiantly it.

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&Item=300381762269&Category=121837&_trkparms=algo%3DLVI%26its%3DI%26otn%3D2

[amberwolf]

At 5Kg I could just use my brushed PMDC 4-pole wheelchair motor, which thru the gearbox (an additional 3 or 4 kg) has enough torque to rip itself off my bike, destroy chains, and yank wheels out of dropouts.

3Kg makes that kind of challenge a lot tougher, *and* it gives back 4.4 pounds that one can use for batteries, cargo, or stronger bike frames.


FWIW, I could probably lighten up an F&P BLDC motor to fit in 5KG, but I don't know what kind of torque it would have. 3Kg is more interesting--there's no way I could cut that much weight off of it so it means trying to think of something even more efficient.

More efficient means better use of the very limited power we can carry, and can mean having to carry less of it to do the same work. So I'm all for a lower limit to this challenge, as it makes for more usable results.

[jscoot]

For specific power, even some dirt cheap RC motors are in the 4.6kw/Kg range. This is with a KV of 130, which easily enables the reduction to be accomplished in a single stage reduction. My own bike is an example of this.

Your motor isn't made to direct drive a rear wheel, you must also incur the losses from power transmission to the rear wheel. The drive train loss between a single stage of 4:1 or a single stage of 10:1 is in the fractional percent area. This is way more than compensated by the broad range of >90% efficiency from the RC motor vs the much heavier and lower efficiency alternator motors.

Including the higher RPM spinning losses of a higher kv motor and the difference of a 4 to 1 vrs a 20 to 1 reduction what is your estimate of total losses % wise between the two if the slower higher torque motor has the same efficiency but over a broader range?

[Thud]

Hello,

Jscoot, just so we are on the same page here, this is the critera the participants of this DIY motor challange are subordinating to:

Miles wrote:
Over 4Nm continuous torque per kg of motor weight.

Less than 3kg in weight.

No energy input other than that to the motor itself.

Capable of practical use on an electric bike.

go ahead & ask clarifying questions if you are participating.
By my count you have linked that e-Bay seller 3 times now.
It is starting to look like an agenda.
(if I want comercials I will sign off the computer & turn the tellevision on.)

If you feel that stongly about PMG/motor conversions, please start a thread & call it "The Worlds greatest e-bike motor for the money!"(or something to that effect.)

At the very least, a builder/experimentor (DIY guy) would build a nicer looking case for the off the shelf parts to add individualality to them, Then submit them to this thread & see how they compair.
Thank you. Todd

[jscoot]

At 5Kg I could just use my brushed PMDC 4-pole wheelchair motor, which thru the gearbox (an additional 3 or 4 kg) has enough torque to rip itself off my bike, destroy chains, and yank wheels out of dropouts.

3Kg makes that kind of challenge a lot tougher, *and* it gives back 4.4 pounds that one can use for batteries, cargo, or stronger bike frames.


FWIW, I could probably lighten up an F&P BLDC motor to fit in 5KG, but I don't know what kind of torque it would have. 3Kg is more interesting--there's no way I could cut that much weight off of it so it means trying to think of something even more efficient.

More efficient means better use of the very limited power we can carry, and can mean having to carry less of it to do the same work. So I'm all for a lower limit to this challenge, as it makes for more usable results.

I suspose so but it also limits a cost effective easy way to get more efficient drive system motors on the road fast! OK I'm done here. Good luck to the few that will be involved in this project.

[amberwolf]

I suspose so but it also limits a cost effective easy way to get more efficient drive system motors on the road fast!

No, it doesn't. It only limits this particular challenge to a more efficiently powerful lighter motor.

There's nothing wrong with spreading the news about PMA motors anywhere you like that's appropriate, and if you have a design that fits within the limits of this challenge, you can show how to build one here in this challenge thread, too.

So I'd say start a thread (or continue one if you already have one) and show how to build them all the way from several ways to acquire a core unit, to how to take several different kinds apart, to how to modify them as needed, rewinding them where needed, etc., all the way up to how to mount them to the bike and build a drivetrain for them for most efficient use.

Then *that* will get more of them on the road fast.

If you sell them premade, then make a thread for them on the for sale section and that will get them on the road even faster if they're cheap enough.

[enoob]

) i like that ignore option aka: foe list

gives me time to stay cool .

This is how you do it Jcoot. may want to cruise this thread randy as it will either excite you or threaten you depending on your real motivation here viewtopic.php?f=28&t=14264
at this point im all in for less $ than what it would cost me to assemble a motor from your links. INCLUDING the gear reduction . making my version easier to bolt on to just about any bike out there. in my humble opinion.

after weigh in this morning INCLUDING my completely untested 4:1gear reduction unit , that is now built into the motor i am at 6.8 pounds . this includes the stock steel stator yet to be replaced if possible with a coreless version . im just gonna pretty it up this afternoon , add some more speed holes and it should lose a little weight still . so ill spend a little time seeing what would be involved in stacking another rotor and stator , see how much that will weigh in at.

Thud the version ill send you will not include the gear reduction ill just include a shaft collar to slip a sprocket onto.

which brings me to the pertinent point for the thread . how or what should i do to the output shaft to best facilitate testing on your end thud ?

[jscoot]

I suspose so but it also limits a cost effective easy way to get more efficient drive system motors on the road fast!

No, it doesn't. It only limits this particular challenge to a more efficiently powerful lighter motor.

There's nothing wrong with spreading the news about PMA motors anywhere you like that's appropriate, and if you have a design that fits within the limits of this challenge, you can show how to build one here in this challenge thread, too.

So I'd say start a thread (or continue one if you already have one) and show how to build them all the way from several ways to acquire a core unit, to how to take several different kinds apart, to how to modify them as needed, rewinding them where needed, etc., all the way up to how to mount them to the bike and build a drivetrain for them for most efficient use.

Then *that* will get more of them on the road fast.

If you sell them premade, then make a thread for them on the for sale section and that will get them on the road even faster if they're cheap enough.

More than likely Miles motor will still be more efficient and reliable for overall use than what motor builds end up being made for this challange.

[TylerDurden]

Draper:

The parameters for the challenge are set.

Get in the game, or get lost.

[Thud]

enoob said,

how or what should i do to the output shaft to best facilitate testing on your end thud ?

Just make it round & I will adapt it to the input shaft of the...... DYNOMOMETER.......
(god I love saying that!)
I will figure out some way to mount it solid & get the readings on it.

No reductions will be tested unless they are integral to the design. (we will leave reductions to another challange thread of someones creation)

[liveforphysics]

Jscoot- I really don't see how you think those converted alternators can compare. You've got thick lams with poor copper fill and big flux gaps, stator teeth done in a grouped series arrangement that gives loads of end losses and weird flux patterns, and it's all put together in a package designed around being bolted to a 400lbs engine where adding weight doesn't make much of a difference.


My motor will be matching the KV of these motors, likely around 1/5th the weight, and easily half the inefficiency of these alternator/motor conversions.

It's like if were all working on building fighter jets, and you keep bringing up an E-bay link to a semi-truck you're selling. Semi-trucks are neat I guess, and even poor efficiency heavy motors have a place in the world somewhere, but I don't see how it applies to this thread.

If you can put something together under 3Kg, it would be great to have another entry in the competition.

[Miles]

No reductions will be tested unless they are integral to the design. (we will leave reductions to another challange thread of someones creation)

It certainly wouldn't be fair to allow any type of torque multiplication to be included in the testing, integral or not.....

If it's not possible to easily disconnect a reduction we could just divide the output torque by the reduction ratio....

[jscoot]

Jscoot- I really don't see how you think those converted alternators can compare. You've got thick lams with poor copper fill and big flux gaps, stator teeth done in a grouped series arrangement that gives loads of end losses and weird flux patterns, and it's all put together in a package designed around being bolted to a 400lbs engine where adding weight doesn't make much of a difference.


My motor will be matching the KV of these motors, likely around 1/5th the weight, and easily half the inefficiency of these alternator/motor conversions.

It's like if were all working on building fighter jets, and you keep bringing up an E-bay link to a semi-truck you're selling. Semi-trucks are neat I guess, and even poor efficiency heavy motors have a place in the world somewhere, but I don't see how it applies to this thread.

If you can put something together under 3Kg, it would be great to have another entry in the competition.

I guess I could enter this motor after putting two of these Ceramic bearings in at a Low Price: $129.00 each. This motor produces over 4 nm of torque startong with a 7 watt 10 rpm spin that you can not stall using thick lether gloves and your hands at 50 watts with the most hand load you can put on the 5/8 shaft. It runs nice and smooth for ebike use up to 60 volts, beyond that you will go too fast. Right now it freespins at 37-39 watts on 52 volts at 3300 rpm. Another motor I have with a kv of 40 will be better for a higher torque test.
It will be interesting to see what difference new bearings will make.

[jscoot]

No reductions will be tested unless they are integral to the design. (we will leave reductions to another challange thread of someones creation)

It certainly wouldn't be fair to allow any type of torque multiplication to be included in the testing, integral or not.....

If it's not possible to easily disconnect a reduction we could just divide the output torque by the reduction ratio....

Unless you did a dyno test for the gearbox for all rpms and loads and added the weight together then deducted the inefficiencies for each rpm and load that the motor was dyno tested at then what you said would be fair. I thought the rules only included the motor ? Why not 5 Kg motors if you allow gearboxes/motors? are the rules changing already?

[Miles]

I thought the rules only included the motor ? Why not 5 Kg motors if you allow gearboxes/motors? are the rules changing already?

Randy, try to understand what I've written before you reply.

[Thud]

I will clarify:
NO reductions will be tested.

I thought someone may get cute & incorperate a planitary mainshaft reduction, totaly intergrated into the "motor"
Definitaly NOT in the spirit of the Challange. (no Kudos for you)

Anyhing submited with a reduction on it, will be subjected to the furnace, poured into ingots & used as the trophy to the leader of the challange.

[Miles]