Grey coating is an insulator, to prevent circulating currents through the bearings from any slight imbalance in magnetic field in the motor. there is a single bearing that is grounded ( the shiny one) to prevent charge build up on the rotor and a flash over to the frame, but the rest have to be insulated so they do not have a shorted turn through the frame that can cause a high circulating current through the bearings that rapidly erodes them through arcing. There are current paths for this current via things like the output shafts and the selector forks, but they probably assumed that, being long thin wall section steel assemblies, this long path would both keep the current low enough not to cause any major extra wear, and also the long output shaft would be mostly self cancelling field wise as well. A lot of larger electric motors handle this with one end having coated bearings, or they make them with ceramic bearing balls inside, or just make both sides with insulated bearing mounting frames, and provide a grounding carbon brush assembly to handle shaft grounding. Drawback of the coated bearing is that you have to ensure that there is absolutely no damage to the coating on the outside and the side facing the frame, so that there is no metal to metal path. However, depending on the exact coating applied, this coat can be both insulating and tougher than the steel of the bearing itself. grey would point to a spray on ceramic coating, probably vacuum deposited before final bearing assembly or applied as a plasma coating.

@WeberAuto

5 жыл бұрын

Fantastic information! Thank you very much! The Nissan Leaf gear reduced uses brushes for shaft grounding. Have a great day!

@ClockworksOfGL

5 жыл бұрын

SeanBZA - Those early Tesla Model S drive failures everyone was talking about a few years ago? That was the far end bearing being eroded by current leakage. There was already a brush grounding the shaft to the case, but it was insufficient. Apparently, the Model S induction rotor pumps out a lot stay voltage compared to a permanent magnet motor.

@WeberAuto

5 жыл бұрын

I wondered if that was the problem with the Tesla bearing failures. Thank you!

@dennislyon5412

5 жыл бұрын

WeberAuto - the Tesla motor issue would seem to have been addressed more recently than would have occurred during the design phase of the Bolt EV powertrain, although we don’t know when Tesla knew of the issue/solution with their motors, and started working on a solution. Unless there was some information sharing between OEMs and suppliers that occurred, I’d think a similar outcome from this issue affecting 2 or perhaps multiple OEMs would be unlikely. This is where information sharing as EV powertrains evolve would benefit us all in the long run. There’s no sense in having ALL OEMs encounter - and learn from - the same failures.

@WeberAuto

5 жыл бұрын

@@dennislyon5412 Thanks for your feedback, I it makes sense to share that type of information if we want to promote the success and reliability of this powertrain type.

My university days are long behind me but I spent 3 hours on 2 videos, without stopping. You give great presentations.

I'm a mechanic of internal combustion engines and you just introduced me to the future of automobiles. I'll remember you to my grand kids years from now when they start to learn to fix their own EVs. Thank you, Sir.

I'm almost retired but want to take this man's classes and start my career all over again!

I had been an auto mechanic for many years. I developed multiple sclerosis which is slowly leaving me dependent on my wheelchair more and more. Watching this video, was amazingly awesome. It gives me hope that even though I'm more dependent on my wheelchair, it doesn't leave me nearly as helpless as I had once thought. Thank you.

@WeberAuto

5 жыл бұрын

Thank you very much! Best wishes

I will never disassemble one of these motor units, but found the whole thing riveting. I cannot begin to understand how engineers design and manufacture this and other precision machinery, it is all beyond my feeble brain. Thank you Professor.

@WeberAuto

3 жыл бұрын

Thank you very much

Congratulations. After all these years on You Tube, at last a professional quality video. A no nonsense, no childish attempted humour. a clean workshop and no dropping tools or bits. From 00:00 seconds to 58:42 seconds it looks to have been well prepared and delivered in a beautiful clearly spoken voice. This is a first class video.

@WeberAuto

5 жыл бұрын

Thank you very much!

@behr121002

5 жыл бұрын

Yes, totally agree about the 'no childish attempted humor'. I am SO tired of seemingly endless video makers who seem to feel that to get information across they need to 'spice it up' with lame humor, or obnoxious rock music or absolutely unnecessary computer graphic intros. It's exasperating. Just clean and clear, understandable, accurate, in-depth information goes SO much farther.

The fact that you can do what you do, by yourself, in a wheelchair, while being both patient and professional, is absolutely amazing. Keep up the good work professor. I'm just a curious viewer but wholesomely impressed by what I see.

Weber Auto is an absolute gift. One can gleam some mighty useful information in these clear, concise, and very educational videos. Thank you for the dedication to teaching us!

@WeberAuto

5 жыл бұрын

Thank you!

I had very little idea of what was going on under the hood of my 2023 Bolt 2LT until I stumbled upon your videos. Thanks for all the time and effort you've invested in this brilliant series. We owners are your beneficiaries!

What can i say that hasn't been said already. Absolutely the best presentation on the Bolt inner workings period! Professor, you sir, know how to teach and illuminate the minds of the curious. Thank you!

I'm an engineer helping design transmissions. Really appreciate your videos, you do an excellent job of understanding and explaining things.

"There are no instructions on disassembling this, so I assume we're not supposed to disassemble it, but that's exactly what I like to do, take things apart i'm not supposed to, as long as I can get them back together and work again" the best quote in the video :) You are one of my hero's professor Kelly, and you inspire me to keep living, even in the darkest hours of life, thank buddy, your content helped to save my life!

@WeberAuto

5 жыл бұрын

Thank you very much! I love exploring technology

@ky-effect2717

5 жыл бұрын

"...but that's exactly what I like to do, take things apart I'm not supposed to.." Right on! I was going to quote him on the same LOL. That's a great T-shirt quote

First time here - I really appreciate how clear and specific you are with everything. Thank you!

@WeberAuto

5 жыл бұрын

Welcome! Thank you very much!

Watched more than once in the past 2 years, and I'm as impressed as I was the first time. What a great production!!

Probably my favorite channel in KZread. The knowledge and communication makes it a pleasure to watch. Thank you for what you do sir.

Wow that hour went by fast! Extremely interesting. Thanks for the video!

@WeberAuto

5 жыл бұрын

Thank you!

Wonderful, detailed video. Thanks for all you do Professor! Have a Merry Christmas!

@WeberAuto

5 жыл бұрын

Thank you and Merry Christmas to you!

The knowledge here that one can pull up day and night is absolutely priceless! Great work.

This is one of most in depth informative channels on youtube. So grateful you're putting this online for everyone to see!!

Spectacularly well done video, sir! You are super great at explaining the design and design intent, and, as you say, the motor is a masterpiece. It's also really great to see a differently abled person doing this sort of work. You extend the range of being for all of us. Thank you very very much.

@WeberAuto

5 жыл бұрын

Thank you very much!

Thank you Chevy designers! I love my 2019 BoltEV. As an efficiency nut, I'm continually amazed by this technology. Keep up the good work - I'm ready to buy a work van version.

Congratulations to Professor Kelly for the clear, concise explanation and GM for their well thought out designs.

Beautiful process and presentation - I had no intention to watch an hour-long drive unit video, but now feel inspired!

Thank you ,professor. I enjoyed the lesson and learned a great deal as well. I look forward to watching your next video.

This was really cool. I'm not even a car guy, but that hour went by really quickly. I love deep dives into the nitty gritty of different technology and you did it while explaining things really well. Cheers!

@WeberAuto

3 жыл бұрын

Thank you!

You are amazing! Just shows that being wheelchair bound doesn't mean helpless at all! You also do a fantastic job of explaining and I really like the attention to detail and all the labeling you do! Thank You for ALL your efforts! I really enjoy your videos!

An amazing video. You are the king of explaining things. Your students are very fortunate to have you as their instructor. I have to tell that I watched all of your Bolt EV videos before I bought my 2021 Bolt. You were a major contributor to me deciding it would be a great car and I really Love. Thank you for being who you are. I’m 74 years old and worked cars all my life and I was surprised on the lack of parts in the drive unit. You explained it very well.

40K miles on my 2017 BoltEV. This is awesome to see. Thank you.

@WeberAuto

5 жыл бұрын

Awesome! 40k miles. Thank you!

I've been watching these videos to start learning about EV's and how they work since my background is piston engines ☺️. fascinating. that bolt drive unit is really thought out!

@bobsaturday4273

4 жыл бұрын

thought out to be a typical gm piece of shit

If I was 20 I would move to whereever this school is and attend. Hybrid training is offered in person boot camp style for less than $2,500 or online for even less. People truly certified in electric cars will be gold plated. Absolutely the best value in education possible.

Probably the best lighting and audio of any automotive how to video series I’ve ever seen on KZread. Content is great, too.

Amazed that you do this all yourself. Great job. I love the end where you appreciate the artistic beauty and elegance of the Chevy Bolt motor drive unit.

@WeberAuto

5 жыл бұрын

Thank you very much! I do get some help from my colleagues with the heavy lifting and moving vehicles.

Watching this, I’m reminded of the gynaecologist, who, trying to broaden his interest, went to a Community College for a course on Auto Mechanics. The final exam involved disassembling and reassembling a car’s engine. He was surprised that his mark was 150 out of 100. When he questioned the instructor, the response was. . . “50 for disassembly, 50 for reassembly, and 50 for doing the whole job through the tailpipe. I am in awe!

@kenjsr1

4 жыл бұрын

😅😅😅😅😅😅😅😅😅

Mad respect for the knowledge! One of the many reasons I've purchased a Bolt was its simplicity. Thank you for the detailed break down video! I'll hop over to watch the one about the battery then the rest.

Thank you professor. It's encouraging to see American ingenuity is alive and well. I love your thoroughness.

Amazing! And with such clear & comprehensive explanation. Thank you so much.

"Simplicity is not necessarily easy." Great video. Really shows how much smaller, simpler, and efficient than ICE.

Thank professor Kelly, I love your calmness and how you tranfer your knowledge. Learned a lot !!!!

@WeberAuto

5 жыл бұрын

Thank you very much

I was looking for a video of a Continental aircraft engine tear down and this came up, It auto started and there went an hour on me, lol. i can say you did a wonderful job showing the motor and I will be looking at your other videos , true professional no BS Automotive and Aircraft Vids are hard to find, This guy is the guy i would love to sit back and have a Crown Royal with and talk . Thank you

That ingenious yet simple design spells longevity in my book . Well done GM 👏👏👏👏

Did this all my life before I retired, and this is an extremely well made video with plenty of tips for 'Flat Rate' Techs that need to gain an edge in knowledge. Congratulations Sir, well done!

@WeberAuto

5 жыл бұрын

Thank you very much!

I am only echoing others when I say this is the best technical video I have ever seen. At no time was I bored. Every bit of information was useful. Skillfully edited and well photographed. Superb work. Your students are lucky to have you.

Bravo!! A very well done and thorough video on the Chevy Bolt drive unit. I am buying a Bolt in 2 days and your videos on its inner workings have truly helped me to understand the amazing quality that has gone into its creation. THANK YOU for your attention to detail!!

The most clear and concise instructional video I have ever seen.Thank you for a highly professional presentation of technology that many of us are still struggling to comes to terms with. I feel so much more enlightened now.

@WeberAuto

5 жыл бұрын

Thank you very much!

Dang John I’ve never seen someone so fast with a impact!! 😂 great video, keep up the good work!

Even more than by the motor itself, I'm impressed by you, Mr Kelly.

@WeberAuto

5 жыл бұрын

Thank you, I appreciate your kind words

Professor Kelly, Your presentation was fantastic . Appreciate the detail and completeness. All the best to you.

Thanks as always Professor!

@WeberAuto

5 жыл бұрын

You are welcome, thank you!

@TheDisgruntledMechanic

5 жыл бұрын

@@WeberAuto Oh and I forgot! congratulations on your TST 2018 Tool and Equipment Awards!

@WeberAuto

5 жыл бұрын

Thank you very much!

@EbmasTR

5 жыл бұрын

Just another great video. Nothing new :)

@wasanthawtentennakoon5117

5 жыл бұрын

Like joining your academy

The most amazing thing - THREE MOVING PARTS and reliability at 54:56 I agree it's a piece of engineering beauty.

Very informative and the simplicity in a remarcable design by GM appreciated.

Thanks Professor for teaching and evaluating EV system design to the public. I learned a lot thanks.

Just beautiful! The beauty is indeed in its simplicity! The passthrough drive shaft is just brilliant. Amazing to conclude that this 4x shoebox produces 360NM and 201 HP.

@WeberAuto

5 жыл бұрын

Thanks for your feedback!

@IntenseGrid

5 жыл бұрын

I agree with that part being simple and elegant. The rest of it, though, I am not so convinced. The transmission fluid cooling of the motor, for instance, seems to me to be a bit difficult to service. Does the level of the transmission fluid not reach the rotor also? Otherwise there would fluid friction losses there.

@OneOfEightBillion

4 жыл бұрын

@@IntenseGrid "seems to me to be a bit difficult to service." Even if this is true, the fluids don't need to be changed until 150k miles!

Thanks, you're a great teacher and it's nice to see the nuts and bolts of the new ev motor.

@WeberAuto

5 жыл бұрын

Thank you!

Your videos bring be back 30 years to being a kid in the garage with dad, being taught how to rebuild chevy small blocks. I have no business in ever servicing an EV, but I still can't stop watching your video's due to the "dad factor" here. Thank you!

Best teacher ever , for the mechanically inclined. Thank's

@WeberAuto

5 жыл бұрын

Thank you very much!

thanks so much for a detailed breakdown so few moving parts & in detail too! its the next generation of people movers ect thanks very much for the vid

@WeberAuto

5 жыл бұрын

Thank you very much!

What a treat to see the electric motor in my 2017 Bolt! Thanks! I've had it about a year. It feels like it could go a million miles. No pistons and valves thrashing about. No transmission. No gas station. No maintenance.

@WeberAuto

5 жыл бұрын

Very reliable system!

@belvedere351

5 жыл бұрын

Would love to see how this compares functionally to the Model 3, also can't wait to hear your opinions on reliability between the two. Thanks again for the hard work!

@waynerussell6401

5 жыл бұрын

@@belvedere351 Million mile Model 3 mule is in good condition: twitter.com/elonmusk/status/1051917544301285376?ref_src=twsrc%5Etfw%7Ctwcamp%5Etweetembed%7Ctwterm%5E1051917544301285376&ref_url=https%3A%2F%2Felectrek.co%2F2018%2F10%2F15%2Ftesla-drive-after-million-miles-test%2F

@ravismaximus7972

5 жыл бұрын

Battery are the fail point in about 5 more yrs and will be more then the car 10 fold good luck

@WeberAuto

5 жыл бұрын

@@ravismaximus7972 Unlike the Nissan Leaf battery disaster, the liquid cooled Chevrolet Volt batteries made by LG are holding up very well after 8 years now. The liquid cooled Bolt EV batteries are also made by LG. Only time will tell, but I suspect they will last just as long.

A tons of researching and dismantling needed to accomplish what you've done sir, im learning a lot from you every bit of parts are totally mentioned you are like a "Book Manual" amazing you are God bless

Thank you, Professor. Want to shake your hand for the great work that you are doing !

Another fantastic video. Very educational. Thank you for making and sharing these!

@WeberAuto

5 жыл бұрын

Thank you very much!

Professor Kelly, You are such a gifted teacher and right to the point including detailed nuances. Thank you for this fabulous vide. Happy New Year to you Thank you so much! Armin

@WeberAuto

5 жыл бұрын

Thank you very much!

Probably one of the best automotive info-video I ever watch!

What a great explanation and demonstration! I am impressed by your knowledge and very courteous video; no annoying music, to the point clear and detailed commentary, a sense of curiosity, honest speculation over points you are not sure about and a very friendly demeanor. That's why I subscribed. Thank-you.

@WeberAuto

5 жыл бұрын

Thank you very much!

Thanks for all your videos. Merry Christmas Prof.

@WeberAuto

5 жыл бұрын

Thank you, Merry Christmas to you as well.

I know your primary intent is to learn, and teach in these. Sometimes you mention something about the design or an improvement (like the incorrectly sized shaft tool), but with all of your experience I'd love to hear about what you think are potential failure points, and weaknesses. Your videos are amazing. Thank you so much for want you're doing.

@WeberAuto

5 жыл бұрын

Great idea, Thank you for your feedback!

@GNX157

5 жыл бұрын

My first reaction was that the electric oil pump was a weak point. Thankfully its external and relatively easy to get to. I hope they have multiple sensors to catch a failure in the pump or motor or loss of oil pressure. GM in the past hasn't been the greatest at making their small electric motors very durable (fuel pumps etc) and letting the economy cost reduction engineers reduce thickness and length of wires, i.e. Not making the wires going to that little motor thick enough and using high enough quality of relays.

Enjoyed watching, thank you for helping me understand how it works and putting it in perspective.

I really appreciate these videos produced by Professor John. Great job. There are generations of technical minded people who can benefit from this.

@WeberAuto

Жыл бұрын

Thank you very much!

You get an "A" in communications skills and the spoken English language.

@fivish

4 жыл бұрын

English? What is aluminum and farenheit?

@squidproquo2241

4 жыл бұрын

@@fivish _ Well, you can tell he is not talking about a female body part when he pronounces "CAN'T", right?

@kevinwilliamson7294

4 жыл бұрын

@@fivish Aluminum is a metal in the boron group, and Fahrenheit is a unit measure of temperature - DUH.....

When I disassembled my dad's rotary engine, I was impressed by its simplicity. However, I didn't know that engine was plagued by problematic high maintenance seal issues. This looks truly high tech and low maintenance. Excellent video.

@WeberAuto

5 жыл бұрын

Thank you!

Great deep dive video, I didn't notice it was one hour long before it was over! Thank you for your fantastic work and sharing of knowledge!

I really enjoyed watching this video, one of, maybe even the best traction motor strip down videos i have seen. The professor was really excellent at explaining everything as he took it apart. Very well done!!

@WeberAuto

5 жыл бұрын

Thank you very much!

Superb and Outstanding Presentation. Thank You Kindly For Sharing. Best Regards.

"You can't be a mechanic because you're handicapped" "Oh, wait a minute... You can?" Very well explained, the video has a pleasant structure and an insight into the additional difficulties you have in a wheelchair. And everything without a helper. I am impressed and hope that I can learn something from it when something is a bit more difficult than I would like it to be!

@WeberAuto

5 жыл бұрын

Lol, yes I can. Thanks for your feedback!

At last, somebody knows how to speak clearly! This man John D Kelly knows how to speak clearly and exacting. Thank you so very much! I am anxious to sit down and watch more of you speak to me as a professional teacher should in every sense of the word. I will be watching and listening to every word you say when it comes down to learning about these amazing new engine technologies

You Are one of the best, most thorough, detailed instructors i have ever had a chance to watch, you are probably better at explaining the concept then the people who designed it!! thanks- Virian Bouze'.

@WeberAuto

5 жыл бұрын

Thank you very much!

Thanks for all your videos. Merry Christmas Professor.

@WeberAuto

5 жыл бұрын

Thank you and merry Christmas to you as well!

Excellent video, very well explained and very clear spoken commentary. Thank you for that. That motor is a master piece of engineering. The coating on the roller bearing is some kind of insulation medium to reduce circulating currents in the armature, which can cause pitting of the races of the roller bearings. Similar bearing coatings are used in large traction motors of railway locomotives and large industrial motors subjected to heavy loads.

@WeberAuto

5 жыл бұрын

Thank you and thanks for the information on the grey coating.

@josepeixoto3384

5 жыл бұрын

@@WeberAuto C A U T I O N (?--lol)----i see now a possible reason to not re-use those shims...that coating... not that it matters much,how can ANY mechanic successfully rebuild that contraption after a major (or even minor) failure!!! it's a mother ... of all complications; i thought it was simple,just an electric motor; silly me!

@rickpaulos

5 жыл бұрын

Jose Peixoto: What mechanic rebuilds engines or transmissions? The amount of specialty equipment needed means we have shops that specialize in doing just one thing. Engine rebuilds, transmission shops, radiator shops, muffler shops, tire stores, diesel fuel injection pump rebuilders, etc. When was the last time a mechanic removed a motor, disassembled it, machined the head, honed the cylinders, ground the crank bearings and cam lobes, etc and reassembled everything himself. The economics make that untenable. Early repairs will be warranty replacements from the manufacturer, then salvaged units and then 3rd party rebuilders. The days of simple electric motors and boat batteries meant a range of 20-50 miles and replacing batteries every year. Hi-tech electric motors do work a lot better. People wreck cars faster then they wear them out so there is a surplus of engines that cost far less than rebuiding. By the time the Bolt warranty expires, there will be plenty of salvaged units available.

@WeberAuto

5 жыл бұрын

@@josepeixoto3384 Yes, the shims are also coated. Reassembly must be done very carefully to avoid damage to any coatings.

@martinstreeworks3310

5 жыл бұрын

Ball Bearing!

salute to professor despite all difficulty he manages to teach

I live in Finland and my English is not very good but I want to say that these videos are so excellent and well done! I have been always interested about all technical things and these videos shows exactly how things works. Also Your English is clear and easy to understand even for me and it makes videos easy to follow. Thank You very much, I hope You will make many more videos in the future! All the best for You sir!

This video and motor design was so much better then I expected but, I can't wrap my brain around the need of the complex shifting mechanism.

@WeberAuto

5 жыл бұрын

Thanks for your feedback. It is a strange shifting system

@oisiaa

5 жыл бұрын

Yeah. That's super weird. My Tesla "shifts" forward and backward electronically and the parking brake just clamps the disc brake rotor.

21:17 Anytime you have to shim pack for play adjustment... there will usually be 2 or 3 different size shims: 1- "face" or "thrust" shims... these will be on either end of the pack, and may be 2 different sizes. They are usually differentiated by surface laminates or composition materials. 2- "fill shims" or "packing shims" are usually made of cheaper materials, as they don't require as much friction/deformation resistance.

@WeberAuto

5 жыл бұрын

Thanks for your feedback

I've watched this video two or three times already. It's such a well-delivered explanation. Highly enjoyable.

@WeberAuto

2 жыл бұрын

Glad you enjoyed it!

Thank you doctor. It is refreshing to listen to someone who knows the details of what he speaks. Truly.

@WeberAuto

5 жыл бұрын

Thank you very much!

Sir, a very Excellent video and disassembly work on this equipment. I enjoyed watching your clear presentation and no nonsense professional attitude. My compliments then. V/r, Steve Ferguson

@WeberAuto

5 жыл бұрын

Thank you!

Excelente EXPLICACIÓN,,, MUCHAS GRACIAS. MÉXICO CDMX

@WeberAuto

5 жыл бұрын

Thank you

Amazing to see the simplicity of design.

After seeing your professional work/explanation even with your difficulty from sitting in wheelchair, it is so amazing and inspiring. From now on I need to improve how I work and change my attitude towards problems that lie in front. Thank you sir.

@WeberAuto

5 жыл бұрын

Thank you very much! Best wishes!

another awesome video, Thanks I really like to see the same disassembly of Tesla model 3 to compare their design approach vs Bolt

@WeberAuto

5 жыл бұрын

Thank you!

@numlockkilla

5 жыл бұрын

Jack rickard, evtv

@AaronSchwarz42

5 жыл бұрын

I second the idea of the Tesla Model 3 comparison, especially since both are American designed & American made :)

and I though scotty killmer was great ...man you are the father fo all mechanics

John, that was bloody brilliant! So I'm off to binge watch the other videos in this series. Keep up the great work. Thanks, Adam, Melbourne, Australia.

@WeberAuto

5 жыл бұрын

Thank you

Dziekuje. Bardzo fajnie, transparentnie i profesjonalnie przedstawia ten naped. szacunek!

@WeberAuto

5 жыл бұрын

Thank you

Great video with the right level of detail! I would LOVE to see you get your hands on a Model 3 drive unit to disassemble in the same fashion.

@WeberAuto

5 жыл бұрын

Thank you, I would like that

"ET" = Extra Terrestrial where I come from! Great video. An amazing piece of engineering. Makes me appreciate my 2017 Bolt even more (34k miles and counting!) But I sure hope my Bolt never needs any service on the 1ET25. Why? Three words, "Chevy dealer mechanics"

@WeberAuto

5 жыл бұрын

Thanks for you feedback. There are good and bad technicians out there, obviously the trouble is finding one you can trust. We are slowly training a new generation of technicians to work on these vehicles.

One of the few Yourube presenters, or any presenter for that fact, that presents facts and not emotions. Great job, as usual!

Excellent and very clear lesson to us non-mechanically oriented. I hadnn't the slightest idea on such a matter. Thank you.

@WeberAuto

5 жыл бұрын

Thank you!

Quite easy to see that this is the future.

@WeberAuto

5 жыл бұрын

Thank you for your feedback

In the first 3 minutes, you perfectly illustrate why we calculate power:) Please understand I really enjoyed the video. My issue was only with a 30 second segment. I mean this constructively. I just hope this helps a few people to begin to understand something very important and elementary about engineering in these subjects... Here's the issue: The statement at 3:30 that the Bolt EV's drive is "more efficient" and a "better design electric motor" could be true, but actually nothing you'd said so far suggests it. The crux of my point is that in order to draw conclusions about performance (how much oomph does the vehicle have) we need to *either* deal with metrics that have those dimensions (power), or know something about *all* major factors that contribute to it. In the case of a vehicle, voltage, current, and torque and speed are all just factors. For example, if we're going to compare lower-dimension metrics like torque (anywhere) between two drives and use that to conclude anything about higher dimension metrics like power, we need to first establish that all the other lower dimension metrics are unchanged or known (which they aren't in this case). Operating voltages or motor speeds between the two cars were never mentioned. So we can't conclude anything about power or efficiency. In more specific terms: In order to know the efficiency of a motor you must compare power-in and useful power-out. Power-in is electrical (voltage x current), and the two forms of power out; mechanical (rotational speed x torque) and thermal (Joules/s, etc...). You have only compared the current of the two motors. We don't know how the operating voltages compare, so we can't know how power-in compares. And on the output side you have only really given torque. We don't know how rotational speeds compare, so we don't know mechanical power-out either. Now it must be said that since we are comparing two small passenger vehicles, we could expect the axle speed to be similar... but I digress. What I'm really getting at is that by just citing the rated power of the Spark EV, we would have had a good sense of how the two drive units compare performance-wise. You had already stated the rated power of the Bolt EV. Then with additional clarification of power in vs out we could then calculate efficiency and even the heat remainder we have to dissipate. It may seem like nit-picking to some, but to the many who pursue and invest in mechanical ideas without understanding what dimensions are, these often becomes toxic misconceptions that seem to last way too long. They are also tragically reinforced by oblivious marketing and other things. Since electric propulsion is still finding new applications, and since in many ways it has fewer design constraints than combustion engines, we often see a lot of variation between the propulsion units of otherwise similar electric vehicles. This makes is easy to show (as you did) that peak motor/engine torque alone tells you nothing about vehicle performance... As you pointed out, It's really all about the "thrust" - torque at the wheels (divided by wheel diameter of course), and to know that you have to know the total gear ratio at the moment in question. But for a given road speed, that ratio (and thus the torque multiplication) is directly related to how fast the motor is turning. So if our goal was to have a sense of how much performance we can expect, we should skip talking about gear ratios and diameters and simply consider the power (torque x rotational speed, or volts x amps x efficiency). Obviously this video focuses on a specific drive system, and so appropriately you dive into that... which was very interesting! I'm just getting at the common dimensional misconception about torque, volts, and amps, and speed vs power. A great example is the cordless tool market. 12V was bested by 18V, 20V, 36V, 60V... and so people begin thinking voltage = power. Nope! The higher voltage HAS usually correlated to higher power, but only because the current is has been held constant the whole time by simple things like standardized battery cell size. Battery packs could have just as easily been made in parallel instead of series and the motor given a different winding, but then we'd see a 3.7 V drill for the same price as a 20V! You would actually have to try it to find that the performance (power) and battery life are identical:) In that market, smaller factors like using lighter gauge wires tipped the scales toward using series packs... If it had gone the other way, we'd be choosing one drill over another "cuz it's got more amps" Lol! This misconception tends to be strongest among groups of people where hardware is the most consistent - where those pesky unknown variables don't change much and using things like torque, volts, or amps, as a performance benchmark is forgiven by the uniformity of the things being compared. Enter the Small Block V8 :) The standardized ways we typically mod combustion engines, increasing the peak torque of a given engine *does* usually increase performance, and so the misunderstanding is reinforced. It is generally true that if you push harder on the pistons, you push backward harder on the pavement as long as it doesn't require you to shift up... it usually doesn't, so folks can continue thinking its all about torque without understanding or caring that they also just increased power. Then there's the very real effect of the shape of the power curve and how this has a measurable effect during takeoff and for discrete-gear transmissions which must spend time off-peak. Aaaand then there's the internet sludge resulting from confusion over units like magic 550 HP-torque "cross over points"... I deeply love piston engines, but I hope as EVs come more into focus, it becomes easier for budding engineers to see how physics works:) Cheers for reading this.

@WeberAuto

5 жыл бұрын

Thanks for your detailed feedback and constructive criticism. The Spark and the Bolt both have 400 V batteries (which I did not mention in the video). Motor rpm of both the Spark and Bolt EV were discussed at 3:25. FYI this is the 7th video in series on the Bolt EV where we totally removed/disassembled/reassembled/reinstalled the 400V Li-Ion battery as well as the other HV components of the vehicle. Have a great day!

@blackmanops3749

5 жыл бұрын

Astute observations and I generally agree. It will be interesting to watch how the general conversation transforms as folks begining to grasp and internalize these "new" fundamentals.

Thanks for the video "Doc Motor"! I have watched an hour long video on the powertrain in my car (which I will never disassemble) simply because you make it interesting. Your presentations are as precise as the specs of the devices you work on!

@WeberAuto

5 жыл бұрын

Thank you very much!

You sir, are a great teacher. I wish I could have been in your class at some point. With an avalanche of content to choose from on youtube it is so easy to start watching a video, maybe jump forward a few times and then click on another video. I watched this entire video. I was enthralled the entire time. Thank you so much for taking the time to record yourself and post this video. Your fast forward edits when unbolting flanges was also spot on.

@WeberAuto

5 жыл бұрын

Thank you very much!