Search found 777 matches

by major
Mar 31 2020 8:52pm
Forum: Motor Technology
Topic: FEMM Simulation Help
Replies: 4
Views: 87

Re: FEMM Simulation Help

If I'm reading the graphic right, you have essentially no magnetic flux encompassing current carrying conductors except for minor leakage. In other words, no interaction between flux and current.
Regards,
major
by major
Mar 28 2020 8:13am
Forum: E-Scooter and Motorcycle General Discussion
Topic: Quality of Kelly Controllers
Replies: 3
Views: 455

Re: Quality of Kelly Controllers

I've never owned a Kelly, but have seen many. I was involved with TTXGP for a few seasons back 10 years ago. Maybe half the bikes ran Kelly's. There were bits and pieces of Kelly all over tracks in NA and EU. Looking at post mortem and attempted repairs in the paddock, Kelly internals sucked in desi...
by major
Mar 18 2020 12:49am
Forum: E-Bike Technical
Topic: Phase Amps vs Battery Amps
Replies: 18
Views: 447

Re: Phase Amps vs Battery Amps

Hi guys, This issue was discussed a short time ago. 3-phase power. Here's a short study I did a while back, for a different reason, but it shows some basic formulas. https://www.diyelectriccar.com/forums/showpost.php?p=376274&postcount=9 Regards, major That post is here: https://endless-sphere.com/f...
by major
Mar 02 2020 12:15pm
Forum: E-Bike Technical
Topic: MOTOR GURU'S, CHIME IN!!!: Which of these motors has better performance?
Replies: 11
Views: 525

Re: MOTOR GURU'S, CHIME IN!!!: Which of these motors has better performance?

In picture#1, it is obvious that the rotor which is shown is not the same as the rotor in the motor due to difference in the output shaft end. Also, on the opposite end of the rotor, at the edge of the photo frame, the commutator and wire connections are just visible. The motor may be BLDC, but the ...
by major
Feb 23 2020 11:23am
Forum: Motor Technology
Topic: 75 KW Axial Flux Motor Design Help
Replies: 15
Views: 939

Re: 75 KW Axial Flux Motor Design Help

Hi ardillo, Very ambitious of you. Too much so, IMO. Suggestion is to start small, say, 0.75 kW. All design characteristic principles are the same. Just scale will save money in long run. Review APL's build thread if you haven't done so. https://endless-sphere.com/forums/viewtopic.php?f=30&t=97860 R...
by major
Jan 31 2020 12:12am
Forum: Motor Technology
Topic: APL's DIY axial-flux motor
Replies: 1017
Views: 86537

Re: APL's DIY axial-flux motor

Not ready for prime time... 3D printing magnets. Just saw this today. https://phys-org.cdn.ampproject.org/v/s/phys.org/news/2020-01-sustainable-3d-printed-super-magnets.amp?amp_js_v=a2&_gsa=1&usqp=mq331AQCKAE%3D#referrer=https%3A%2F%2Fwww.google.com&_tf=From%20%251%24s&share=https%3A%2F%2Fp...
by major
Jan 29 2020 3:25pm
Forum: Motor Technology
Topic: Motor internal temp?
Replies: 5
Views: 346

Re: Motor internal temp?

Thermal inductance is just an analog to electrical inductance. Electrical inductance has no influence on thermal behavior of electric motors to my knowledge. Forget about it.

major
by major
Jan 29 2020 9:59am
Forum: Motor Technology
Topic: Motor internal temp?
Replies: 5
Views: 346

Re: Motor internal temp?

I think it was buried in the hub motor thread but looking for results comparing sensors within the windings revealing the wire’s true temp as apposed to just the case Hi, I suspect any general or "of thumb" rule will be inaccurate for your specific application. Of course, I don't know the tolerance...
by major
Jan 23 2020 4:28pm
Forum: Motor Technology
Topic: Revolt RV-series motor review and comparisons
Replies: 286
Views: 34905

Re: Revolt RV-series motor review and comparisons

... Peak efficiency is the point where while under load the copper losses and iron losses are equal. ... Hi John in CR, I've heard this statement a number of times recently. I don't recall having ever encountered it last century when I was learning motor theory. Do you have any idea of the source o...
by major
Jan 23 2020 8:40am
Forum: Motor Technology
Topic: Revolt RV-series motor review and comparisons
Replies: 286
Views: 34905

Re: Revolt RV-series motor review and comparisons

3-phase power.
Here's a short study I did a while back, for a different reason, but it shows some basic formulas.

https://www.diyelectriccar.com/forums/s ... ostcount=9

Regards,

major
by major
Jan 21 2020 7:06am
Forum: Motor Technology
Topic: Revolt RV-series motor review and comparisons
Replies: 286
Views: 34905

Re: Revolt RV-160-SH update

I have the RV-160-SH running on a 24 fet Nucular controller now. After a bit of set up, the motor is running great. At 82v I am seeing 6 battery amps and 10 phase amps under no load. It's not the best for efficiency as that's 820 watts just to run the motor. I'm sure with 3X the original copper cro...
by major
Nov 29 2019 10:51am
Forum: Motor Technology
Topic: OSU electric motor
Replies: 2
Views: 592

Re: OSU electric motor

Thanks for the heads up Jones. Interesting. The stator coils appear to be well over half conductor length as end-turn. But then again, that portion is of larger cross sectional area so mitigating resistive loss. I wonder how they fabricate the inside out cage on the rotor. Be awfully large for a die...
by major
Nov 19 2019 8:26pm
Forum: Motor Technology
Topic: aluminum windings
Replies: 3
Views: 827

Re: aluminum windings

Warren wrote:
Nov 19 2019 4:51pm
To show this in a direct comparison, the Fraunhofer team used 250W commercial pedelec motors.

https://www.greencarcongress.com/2019/1 ... -ifam.html
My BS detector is ringing off the hook. Any data or white paper showing verification testing method?

major
by major
Nov 07 2019 2:46pm
Forum: Motor Technology
Topic: APL's DIY axial-flux motor
Replies: 1017
Views: 86537

Re: APL's DIY axial-flux motor

Hi APL, I'll refer you to a thread on end-turns mentioned before. This post in particular. There could be iron inside the solenoid coil. Makes no difference on the magnetic path outside the coil. ... BTW, I used the term "core" when addressing Ampere's Law because of the motor context. It is actuall...
by major
Nov 05 2019 9:39pm
Forum: Motor Technology
Topic: APL's DIY axial-flux motor
Replies: 1017
Views: 86537

Re: APL's DIY axial-flux motor

... I think the answer is that these coils are normally used on motors without permanent magnets where torque comes from reluctance (Swichted Reluctance Motors) and so the entire winding, no matter in which direction it goes, contributes to torque. ... here is the source: https://things-in-motion.b...
by major
Oct 24 2019 8:57pm
Forum: Motor Technology
Topic: Same debate again, motor windings!
Replies: 96
Views: 5418

Re: Same debate again, motor windings!

Punx0r wrote:
Oct 24 2019 5:28pm
sn0wchyld wrote:
Oct 24 2019 4:57pm
end turns are still contributing to usefull flux
Are they?
No.

Been through this on this forum before. I'm not too familiar with this forum search feature. Some recent white papers on the subject show negligible results. Or study Ampere's Law.

Regards,

major
by major
Oct 11 2019 10:51pm
Forum: Battery Technology
Topic: Lithium Batteries Shipping Rules Discussions
Replies: 291
Views: 76247

Re: Lithium Batteries Shipping Rules Discussions

Well, not necessarily. I am the recipient of the package so how can I be responsible for the sender not putting a sticker on the box? The sender is the one who ships the package and is responsible for following the law and rules. The recipient has no control over that. I am stating my opinions base...
by major
Oct 11 2019 7:10pm
Forum: Battery Technology
Topic: Lithium Batteries Shipping Rules Discussions
Replies: 291
Views: 76247

Re: Lithium Batteries Shipping Rules Discussions

My understanding is you abide by the law or risk prosecution meaning fines and jail time. I would not expect a warning or mere confiscation.
by major
Sep 22 2019 12:31pm
Forum: General Discussion
Topic: 48v Ebike battery powering cordless 40v chainsaw or trimmer?
Replies: 14
Views: 1644

Re: 48v Ebike battery powering cordless 40v chainsaw or trimmer?

Hi, I've hacked a number of battery powered tools. A lot of older ones which used nicad/nimh. I've gone over voltage on a number tools without problem. A DeWalt screwdriver originally used 7.2V. Never ran better than now with 12V Lithium. I think my vacuum sweeper was like 16V nicad, now 19.2V Lithi...
by major
Sep 20 2019 4:35pm
Forum: Battery Technology
Topic: When to charge the acid battery properly?
Replies: 82
Views: 2941

Re: When to charge the acid battery properly?

borko444 wrote:
Sep 20 2019 12:13pm
Now after 19 km.
The battery is 77 volts.
Batteries average 12.83 Volts.
Check out the video.


[youtube]https://www.youtube.com/watch?v=z5l998v24Ao[/youtube]
Nice job dude. Like it. Easy to measure. Easy to equalize charge when needed. Good luck.

major
by major
Sep 20 2019 1:07pm
Forum: Motor Technology
Topic: Controllers - do they only manage duty cycle?
Replies: 4
Views: 426

Re: Controllers - do they only manage duty cycle?

Hi,
All that the controller can really do is switch. That is to turn on and turn off the switching devices, mosfets, IGBTs, or whatever. Everything else is just figuring out when to do it.

And I = V/Z is valid at stall, otherwise you must include a generated voltage in the equation.

Regards,

major
by major
Sep 11 2019 12:38pm
Forum: Battery Technology
Topic: When to charge the acid battery properly?
Replies: 82
Views: 2941

Re: When to charge the acid battery properly?

... And don't be confused by the the difference between equalizing the 6 internal cells that make up one 12v battery, and balancing the 6 whole batteries in your 72v string. The first is done automatically by a good charger, but not the second. Hi Voltron, Can you support your underlined statement ...
by major
Sep 11 2019 12:05am
Forum: Battery Technology
Topic: When to charge the acid battery properly?
Replies: 82
Views: 2941

Re: When to charge the acid battery properly?

Here's a paper on lead acid charging explaining the algorithm including float and equalization stages. You should check with your particular battery manufacturer for his charging recommendation.

https://chargetek.com/images/pdfs/equal.pdf

major
by major
Sep 10 2019 5:22pm
Forum: Battery Technology
Topic: When to charge the acid battery properly?
Replies: 82
Views: 2941

Re: When to charge the acid battery properly?

Most lead acid battery chargers take care of balancing series strings by using a float or equalization voltage after the bulk and absorption portions of the charge algorithm. With a good quality charger, this should be enough. With most lead acid batteries you get a 6 cell (12V) jug (case) with does...
by major
Sep 10 2019 7:45am
Forum: Large EV General Discussion
Topic: For an electric kart, what is the relationship of torque and power?
Replies: 5
Views: 1503

Re: For an electric kart, what is the relationship of torque and power?

Power = speed times torque.

Watts = Radains per second * Newton meters
(w = rad/s * Nm)

or

Horsepower = Revolutions per minute * pound feet / 5252
(hp = RPM * lb.ft./5252)

Relationship is true for all rotational power including karts.

Regards,

major