Cybertruck 48V Motors: Why Tesla Made the Jump

[@JoelSapp]

Yes, the use of I for current in the equation V = IR comes from French and Latin. The symbol I is derived from the French word “intensité” (meaning intensity), which refers to the intensity of the electric current. The term itself has Latin roots, where “intensitas” conveys strength or magnitude.

[@peterzerfass4609]

It's interesting that the 'language of science' has changed throughout history from latin/greek, to french, to german - and for some subjects a bit of russian - now to english...and who knows what it will be tomorrow. But the symbols that were introduced during each period still stick around so you have these different language roots to them. When electricity was being researched as a hot topic it just happened to be french and so a lot of the stuff we got there has french roots (also from researchers names. E.g. Coulomb and Ampere)

[@razvanmargineanu]

I came here to write this. Thank you.

[@Sajentine]

They should really teach that in school when teaching these equations. It makes learning them so much easier.

[@jacqueswinter]

But they're cheese eating surrender monkeys (joke!)

[@JoelSapp]

@@Sajentine I do remember my highschool physics teacher telling us this but it wasn't stressed. More of a factoid.

[@olafv.2741]

You didn't mention the savings in wiring. The wiring can be thinner, lighter, and cheaper and takes up less space.

[@4literv6]

It's also more efficient overall to! 👍🏻😎

[@jamarforsythe7262]

Gotta save some details for the reports they sell 😅

[@MrAdopado]

They mention it in every other 48V video so perhaps they realise everyone knows by now!

[@PaulTurnbull-EMfield]

​@@MrAdopadoYes, I didn't mention it in this video because we did a whole video emphasizing the savings in the wiring harnesses earlier.

[@Pikminiman]

He mentioned quartering the diameter of windings in the motors. Same principle.

[@Ray_of_Light62]

I recall how the old automobiles had a six volt electrical wiring. A 55 Watt headlight bulb draw nine amperes! The wiring and the switch easily lost 20% of the power. The change to twelve volt electrical system required a somewhat more expensive battery, but reduced the losses four times, to a much more acceptable 5%, and made electrical switches and all copper wiring much more economical...

[@mjedrezyk]

We had 1968 Trabant 605 with 6V. Two-cycle engine making whole 27 hp….

[@paulmeynell8866]

Yes I remember putting some hefty cable in to power my 1980’s spot lights!

[@ronroberts110]

After WWII, higher octane gasoline became more readily available, so engines could use a higher compression ratio. This had the side effect of being harder to turn over the engine, so rather than use a larger starter and more amps, everyone agreed to go to 12V

[@chrisheath2637]

As an old electronics dude (robots) - I have learnt a lot about car manufacturing from the Munro videos. "MOSFETS" are actually quite amazing. In the old days, valves were used (massively inefficient, due to the heaters required).Then transistors came along, which were better, but still plenty of losses. Mosfets, (Metal Oxide Semiconductor Field Effect Transistors) since they were first used, have become incredibly low loss ( and improving constantly). They are needed to power brushless motors - which require high current, at high switching speed. (As Paul mentioned - more MOSFET current = more expensive). Perhaps Paul could do a quick video about brushless motors (which require sophisticated control)( themselves an advance on DC motors - which were relatively simple to drive)...

[@NotNowLater]

Brushless is definitely the way to go for motor durability. I used to make brushed motors and the brush is easily the weakest part of the motor wearing out faster than other parts of a motor.

[@ronblack7870]

are you in UK.? valves ? do you mean diodes?

[@BellaNash]

No, he means vaccunn tubes.

[@briangman3]

With you !

[@jimparr01Utube]

The main loss for MOSFET technology, apart from the on/off switching speed, that can be, but is usually not significant, is the single parameter RdsON. This is basically the resistance of the Drain-Source that carries the switched current. A number of years ago, manufacturers cracked the sub1 ohm barrier. Now, manufacturers like Nexperia are claiming sub 1 milliohm without undue compromises. This is a huge advancement for low voltage motor control of significant power, because in many cases, little or no heating and therefore sinking of thermal losses is required to efficiently manage power to the load. BTW, thanks Munro Live for the heads-up on the new paradigm that is 48V.

[@gregeconomeier1476]

Thank you for including the math. The issue is much easier to understand.

[@MunroLive]

Glad it was helpful!

[@darylfortney8081]

Higher voltage improves the efficiency of power transmission not consumption. That is mostly a requirement set by the actual work that ultimately needs done, rolling the windows up for example. The car still requires the same power to move at the same speed down the road. Its about how much power is lost getting the power from the battery to the actual wheels.

[@hautam539]

You are correct sir. The higher voltage the lesser lost of power during transport from source to device. That why we used 400-500 KEV instead of 120 Volt to transmit electric on long range power line.

[@youngmonk3801]

I've heard even 24v can fry relays...wont the 48v make relays wear out even quicker, or weld contacts together?

[@darylfortney8081]

@ should be longer lasting since lower current produces less heat. Current is what welds contacts

[@bondarenkodf]

The symbol "I" is used to represent current (measured in amperes or amps) because it originates from the French word "intensité", which means intensity of current. When electrical notation was being developed, the letter "I" was chosen to represent current due to this linguistic origin, while "A" was already designated for the unit of measure, amperes. Thus, in electrical equations and notation, "I" refers to current, while "A" refers to the measurement unit, amperes.

[@andrewsmith1735]

Indian watches rabbit while eagle Flys overhead

[@sjurduri]

Interesting. I have spent days and months calculating electric problems, and have never known this. Also we don’t use “V” for voltage in the formula. It’s “U”. So the formula goes P = U x I

[@MrMMrulez]

The convention to use I for the electric current from the Latin word "intensitas" was introduced by André-Marie Ampère himself.

[@robertthallium6883]

For native English speakers, he means "The convention to use [the letter] *I* for the electric current"

[@PaulTurnbull-EMfield]

Thank you

[@windsine]

The cross-vehicle wiring can be 4x smaller cross-sectional area so harnesses can be lighter weight and cheaper to manufacture.

[@alanmay7929]

and other parts significantly more expensive lol..

[@themonsterunderyourbed9408]

​@@alanmay7929 not if they are produced at scale.

[@bondarenkodf]

For the same 100 watts of power delivered through a 2-meter (this is the length of one large human, or NBA player) wire with a cross-sectional area of 2.5 mm² (~14AWG), the power losses due to resistance are - 12V system: 0.93 watts, 48V system: 0.06 watts. As you can see, the power loss in the wire is significantly higher for the 12V system compared to the 48V system. This is because the current (amps) is much higher in the 12V system, and losses increase with the square of the current (I²R losses). The 48V system is much more efficient in terms of power loss in the wires.

[@dantronics1682]

you should state loss as heat, the same amount of electrons that went in came out

[@myid9876543]

Sure, but one watt is tiny. I mean, I thought this was a good idea until I read your comment.

[@myself248]

@@myid9876543 The more significant difference is that you can use thinner wire for everything while still keeping losses and heating within acceptable bounds. Harness weight is significant, easily 100+ lbs in modern cars. Assume that you need some minimum size for mechanical strength, so 1/4 the current doesn't let you go to 1/4 the wire size but even if you only get 1/2 the size, that's still significant. (Insulation thickness at these low voltages is also dictated by physical durability rather than withstanding voltage, so it doesn't change.)

[@GntlTch]

Except Paul's argument is that one needs 16x the length of wire to produce the same magnetic field. Sixteen times 0.06 is 0.96, 0.03 watts greater than the 12 volt system. However, the glaring error in Paul's math is the assumption that power in remains constant. Not true. Only the torque must remain constant. If the motor can be made more efficient that lowers the electrical losses and thus the current requirement. The physics of motors, electro-magnetic fields, back EMF, etc does not result in linear relationships! Or, perhaps changing the gear ratio of the motor would be beneficial. In any case, I think Paul made his point - switching to 48v systems is not a trivial task.

[@yottabit]

Love these presentations from Paul. Never thought I’d be binge watching electric motor content

[@andutei]

The MOSFETs for the 48V drive are higher Vds rated, so not 1/4 the size / price. Die area goes up with the square of the voltage rating and inversely proportional with Rdson. So for 4x the voltage at 1/4x the current keeping same resistive losses (MOSFET conduction inverter losses are 3 * Irms² * Rdson) the MOSFET dies are 4x the area!

[@grekiki]

I don't follow. With same losses, wouldn't R grow 16x so total area stays the same?

[@andutei]

You're correct. Keeping losses the same, R should increase 16x for 1/4 the current. So die area stays the same overall. Sorry for the confusion.

[@ABa-os6wm]

Die costs are not the most relevant for smallish mos today. Often the package costs more than the die. Cost of package reduces with current.

[@yolanda4731]

Thanks for another great video. When my husband and I are out in the CT together - people approach him to ask technical questions. He says - “ask my wife - she’s the expert”. Thanks Munro 😊

[@pgrts]

I have always learnt the Ohms law as U=RI and P=UI U is the difference in voltage, not necessary the voltage to ground. Simplify it to Volt=Ohm*Amps and Watt=Volt*Amps

[@codefeenix]

one thousand ohms * 2 amps = 2000 volts? are you insane?

[@pgrts]

@@codefeenix That requires a 4 kW resistor (heater) or a very long copper wire. I have worked with about 6000 Amps - but really low resistance and low voltage (for heaters). And also worked with 50 kV for power distribution. But you seem to be far off the 48 volt used as low voltage in the CT.

[@stevenhamerlinck6832]

That still is correct. Typical (EU regulations) is 6A / 1 mm2 cross-section of the conductor for safety. The resistance depends on the material used (fact: it's not always copper, especially in high-voltage cables). The 48V was aimed at exactly this-> increasing the voltage decreases the amperage for the same power (factor 4 here -> take 200W with 48V = 4.16A, => 12V = 16,6A). This implies for a 48V system, you can safely use 1mm2 cables with safety margin. For the same 12V system, you need a 3mm2 cable for similar safety margin.. ripper weighs approx 9gr/cm3. If we assume copper, that comes down to approx 9gr of conductor-material, for insulation I used PVC which is 1.4gr/cm3. If you do the math, a 1mm2 cross-section cable with 8 conductors, that are individually isolated and contained in a jacket-insulation (and exactly the same for the 3mm2) it would come to this for every single meter of cable: 135gr for the 1mm2 and 310gr for the 3mm2 cross-sections or close to 2.3x the weight. Again, this is very basic insulation, very basic assumptions, the real cables surely are better insulated thus heavier thus the effect between 1 and 3mm2 will be larger, and that is only for the SAME amount of cabling, which we know Tesla reduced drastically because of the Etherloop application which would be impossible without the 48v architecture. The CyberTruck will surely have more then 100mtr of cable thus 13.5kg compared to 31kg is decent weight savings that helps to translate into energy-savings. There is an additional kicker as well that helps with energy-savings. The power though the etherloop-bus will not always be at 80% since not everything needs to operate at full-power all the time. Due to the larger cross-section, the resistance for the current is lower even at 50% or 25% utilization, thus the voltage drop due to cable-less is lower = less energy lost (and also less heat-losses in the cables). I have always wondered why this wasn't done like this in transport (cars, trucks, vessels, ...) for the past 25yrs or so... (Ever since learning about Ethernet & TCP/IP)...

[@karbanatek99]

"mister U is IRish...

[@bobelmer2641]

Watching this was time well spent. Terrific concise summary of benefits of 48V architecture by Paul. TY.

[@Clark-Mills]

Smaller connectors, thinner wire. Combined with the door controller board and Ethernet you have only power and network going to a door controller... the door controller really runs the show within the door. All part of Tesla's drive toward modular builds. No wire looms run into the door; just unplug the Ethernet and power connectors.

[@BellaNash]

Only power and Ethernet, this improves on only power - in no way. The board handles current but it also consumes current.

[@whatusernameis5295]

​@@BellaNashbut the 48V system is standard Ethernet voltage and also requires ¼ the amps compared to a 12 volt system

[@spamin8r]

I had an electronics instructor explain back in the day that "I" stood for intensity, and was used widely before we changed the name to amps to honor Ampere. The name changed, but the schematic symbol didn't because it was already established. Whether that's true or not I'm not sure.

[@melllvar4262]

You are correct 👍( Intensity )

[@brunonikodemski2420]

This is excellent. Our company developed the electric turret for the LAV combat vehicles, transitioning from a 24V system, and realized that you HAD to go to a higher voltage. We went to 150+Volts, due to 115Vac recharging capability. Worked great. Later, as EV cars evolved, the same arguments applied to higher voltages, and now sitting at about 800V. The limits are essentially the "materials and insulation costs" involved with making these higher voltages safe to handle, and/or repair. Materials at these voltages WILL have an accelerated degradation lifetime. It is yet to be seen what the actual repairability time lifetimes will actually come into common useage, versus the "throwaway costs" of a battery and electronic processing system.

[@billpilaud8647]

SLEV safety extra low voltage for DC is 60volts - 48V with surge overhead will not be dangerous to techs, dogs and children if they are in contact with this voltage. Anything higher is dangerous.

[@matthewgiannotti3355]

Ampère labelled the flow of charge “intensité de courant”, meaning current intensity, and gave it the symbol “I”.

[@danharold3087]

The confusion arises from not distinguishing between system-level effects and device-level effects." This confusion seems to have gained considerable traction. Kudos.

[@thedownwardmachine]

The vehicle wiring argument has been done to death. Nice to see the ramifications on the end components.

[@themonsterunderyourbed9408]

I'd argue it hasn't been done enough since other manufacturer aren't jumping in to start implementing the 48v systems..

[@AdityaMehendale]

Errata: Torque times angular velocity is power; with power P measured in watt, torque TAU measured in N.m and angular speed measured in radian/sec (all SI-units) , no "RPM" rubbish. Same holds true for EMF "U" (measured in volt) and current I (measured in ampere) SI is VERY clear and VERY consistent in nomenclature, and the balance and interplay of various quantities.

[@bpark10001]

Every "magnetic thing" works independently of the voltage/impedance level it is designed to work on, assuming wire packing factor doesn't change. Practically, packing factor stays reasonably constant as long as the voltage level is not "ridiculously high" or ridiculously low". So the analysis you make also applies to every other magnetic component in the circuit (such as inductors & transformers in the electronics).

[@DouglasJMark]

Paul, math is awesome. Keep these easily understandable and helpful videos coming. They are wonderful to better understand the first principles of BEVs.

[@jbbuzzable]

I know more about electricity than the average person, but this video explains more clearly what the advantage of 48V is about.

[@davidfenwick987]

Great job, speaking as a tripple E graduate and Physics teacher, you made it so clear and accessible!

[@JosefRaschen]

48V is also a disadvantage if you have to step it down for example to 3.3V. Switch mode regulators usually have higher losses if the voltage drop is high. So you might have to use multiple steps, which increases BOM cost.

[@a2cryss]

I believe the CT also has a 12v system so it could use that for the lower voltage lower power devices.

[@ChessIsJustAGame]

Why 48V? Not just 4x? 50Vdc requires more safety issues to address. Same goes for aerospace, etc. 48Vdc is a standard so easier to design using off the shelf parts.

[@AlexanderSh-t9w]

It is the highest standard voltage for low voltage directive.

[@chrisdrake4692]

You meant > 50v (greater than). Because, 50v (exactly) and below is legally considered "safe". Is any distinction made between AC and DC at

[@AlexanderSh-t9w]

@@chrisdrake4692 50V is the limit, over it must be very different insulation etc. But taking into account voltage ripples and regulation errors makes only "48V" practically usable.

[@bondarenkodf]

I believe the main economic benefit comes from the use of smaller wire gauge to deliver the same amount of power. Additionally, a certain percentage of watts is saved due to the reduced current over a given distance, factoring in the wire's cross-sectional area (mm²). The savings are not necessarily from the motor itself.

[@owenturnbull6424]

Nice clear technical explanation, thanks Paul!

[@MunroLive]

Thanks for watching!

[@jackgreenstalk777]

"The conventional symbol for current is I, which originates from the French phrase intensité du courant, (current intensity). Current intensity is often referred to simply as current. The I symbol was used by André-Marie Ampère, after whom the unit of electric current is named, in formulating Ampère's force law (1820)."

[@GregHassler]

They could also redesign the motor with a different reduction gear and spin it faster. They're just trying to keep it in their same form factor.

[@Ask-a-Rocket-Scientist]

Couldn't you spin the motor at 4 times the speed with the same windings and let the gearing fix the window lift force? The higher voltage can handle the back emf.

[@dragosmihai3489]

...if the insulation can take it I'm sure it can do that, but at vehicle level does it make sense? The way to look at this is, the window motor is a toss-up, could have stayed a 12. However, since DCDC-s are expensive, no need to step down the HV bus to 48V (necessary for the power steering) and 12V (legacy) - the easiest is to go 48V everywhere.

[@kazedcat]

Yes it is possible but it will take a complete redesign of the device instead of just a motor replacement. The reason why it could not gain better efficiency is because they did a quick modification of the device instead of a complete redesign from scratch.

[@SeaMushroom98]

It’s easier to rewind the motor for the voltage you want than to make a custom gearbox for a single SKU. these windshield wiper motor assemblies are sold by the millions, and mostly share the same mechanical assembly. Changing the gearing may save you a tiny bit of efficiency or size but you’d negate the value created by making it more expensive.

[@stephenj4937]

@@dragosmihai3489 but you still need 12V for 12v power points (cigarette lighter plugs) in the vehicle. Or does the Cybertruck not have any?

[@johnpoldo8817]

Please don’t omit the math on Munro Live. We engineers love it.

[@ch4.hayabusa]

The real reason is for the 11kW AC outlets as standard... The cost of the optional Ford solution is probably double the cost in converters and copper.

[@yorkchris10]

Our railroad used mostly 24V DC switch machines, but in the yard they sometimes used 110V DC. Even with long cable runs, the V was high enough to move the points in very cold weather and at good speed.

[@nuttyDesignAndFab]

your 48V example is a little misleading; I could run the same physical motor as in the 12V case at 4x the RPM using 48V with 1/4 the current & torque, use a gearbox to the get speed/torque I want and in the end get higher efficiency out of the system. if higher voltage doesn't lead to higher system efficiency, then why not have the main high power battery be 48V instead of 400V and save the hassle of having to deal with HV safety?

[@wtmayhew]

If one wants a 48 Volt low voltage bus for whatever reason, I suspect altering the amp-turns in the motor armature is less expensive than asking the supplier to redesign the gearbox of the window regulator motor. Also, assuming it is a cheap brushed DC motor, keeping the armature current lower will help the brushes last longer. The motor is only used a few seconds per day, so brush life probably isn’t major consideration. As far as going to am48 Volt main battery, it certainly is possible. The problem is with something like 800 HP or ~600 KW collective for the traction motors, that means a current draw of ~12,000 amps. That would require a lot of beefy MOSFETs paralleled to handle as well as heavy gauge wire. It is probably cheaper to have fewer high voltage MOSFETs versus more low voltage MOSFETs in the drive electronics.

[@nuttyDesignAndFab]

@@wtmayhew first point: yes, using the same motor with different amp turns is an economic decision, not an engineering one. second point: so you're saying the vehicle would have to be much heavier. what does weight do to vehicle efficiency again?

[@wtmayhew]

@@nuttyDesignAndFab Manufacturers make their decisions based on what will minimize their per unit cost to meet a performance specification, often unrelated to the theoretical beauty of an engineering approach. Efficiency is related to vehicle mass. An often cited engineering rough estimate is that each percent change in mass is equivalent to the same percent change in energy consumption. “Weight,” as used above refers to wire diameter. The engineering estimate from UI Physics Dept. is that for low frequency power transmission, 700 circular mils per amp is required. 12,000 amps requires the cross section equivalent to 12 4/0 conductors per terminal. That is milage is split between front and back. A 4/0 wire has a conductor diameter of 0.46 inches and mass of 0.653 lbs/foot. There would probably be a total of about 25 feet of conductor(s) for both battery terminals. That is about 196 pounds of copper wire plus insulation for a 48 volt system versus 32.5 pounds of copper for an 800 volt system. Clean copper suitable for wire is about $3.65 per pound. Just in the reduction of copper required, $596.78 would be saved. I’ll leave it to someone else to figure out the costs of the MOSFETs needed for the drive electronics. From an efficiency standpoint, the mass reduction is about 2.3% of the Cybertruck 7,000 pound curb weight (total mass). A ~2% to 3% reduction of energy consumption is worth doing for the customer because it adds up over the service life of the vehicle.

[@nuttyDesignAndFab]

@@wtmayhew bro my points went straight over your head.

[@spelare2]

- **U** is the voltage (potential difference) across the circuit (measured in volts, V), - **I** is the current flowing through the circuit (measured in amperes, A), - **R** is the resistance of the circuit (measured in ohms, Ω).

[@MrEmalgamist]

Love the "Hi Sandy" printed on the PCB board (8:15 by his thumbs knuckle below what looks like a constellation). They knew.

[@PaulTurnbull-EMfield]

The constellation is Taurus. It's a reference to the Ford Taurus, an influential vehicle that Sandy was involved with during his time at Ford. You can see one in the background.

[@envisionelectronics]

I design boards for them too. They always want me to add my special flair. Should I give a shout-out to Sandy in the new 3/Y boards? Let me know.

[@JamesSmith-yb2vi]

I = Intensity of the current in Amps, I did study this in high school in Est Europe in 80's it was part of the physics lessons. When you increase the voltage you make the diameter of the wire thinner. The more coils you have in the coil the higher is the magnetic field when the currents runs in the coils. If you want high torque, you need high voltage, more coils on the electric engine, and lower current.

[@abid583ind]

The 48v setup is going to only help in the steer by wire feature where there would be significant/continuous power demand, all windows, wipers, door motors are way low in the fraction of decimals in terms of power /efficiency considerations.....

[@JonathanTamm]

The front windscreen wiper is very large, then there is the rear cover, it took 50 years to go from 6 volts to 12 volts Tesla is going 4 x in one go giving twice the previous jumps should be good for 100 years

[@clarkleakins879]

Lower current through the MOFSET/electronics is healthier, less heat damage. Heat in the electronics is what often kills Tesla systems. This is what they have learned from Roadster, Model S/X systems. And small wire costs less. And electrons travel on the wire surface, not within the wire. And smaller wire connectors to ribbon wire is easier.

[@AlexanderSh-t9w]

Skin effect is for AC only i.e. for motors, inductors but not the DC power cables at all.

[@Chas_Reno]

Thank You. Nicely explained. I would expect all new Tesla models to go this route... i.e. Cab, and next gen X,Y, 3...Semi, Van and Bus.

[@gbinman]

I have never heard that 48v was more efficient. All the hype was about reducing wiring diameter, weight and using less copper.

[@jamesengland7461]

Those are efficiencies in a different way

[@gbinman]

@@jamesengland7461 those were the efficiencies that I thought of. I have a background in the electrical side and didn't expect power efficiencies in devices.

[@danapeck5382]

What a great segment! As a liberal arts car enthusiast, I came away feeling much better informed. Thanks! I wonder if the SpaceX/Tesla materials science folks are working on high temp superconductors

[@JFabric500]

There’s a graph out there showing where copper production will need to go if we reintroduce manufacturing to the US, then overlayed with Data Centers draw. This is a “if we don’t change now we will only change when we are in full pain” moment. They are ahead of the curve per usual.

[@GilmerJohn]

The BIG negative is going to 48 volts is that the housekeeping batter becomes less reliable. If a lead acid batter is used, it goes from 6 to 24 cells. If it's a lithium battery the battery management problems start approaching that of the high voltage battery. It's good to have suspension pumps and steering motors more powerful. The 48 volt housekeeping permits the designers to run all but the main drive motors from 48 volts rather than the high voltage. In particular, the heat pump might be the "right size" to run off of 48 as compared to, say, 600 volts.

[@jackcoats4146]

The "I" symbol comes directly from the French term "intensité de courant." ... So says Google. Currently 48V isn't cheaper, but long term it will be once more of it is used. I wish I could afford your report, but just being interested and not in the field, it is more than I can deal with. Still a great supporter of you guys!

[@budgetaudiophilelife-long5461]

🙋‍♂️PAUL,THANK YOU AND MUNRO FOR SHARING THIS 🧐⚡️⚡️⚡️

[@yokaibyte2133]

Someone I know deals with/produces Tesla's semiconductors (He works at TI). He says they aren't that great. What are your thoughts?

[@erik2k09]

Only 3 steer by wire motors. Rear steer is only one motor

[@madintheheid]

From this observation, he developed the eponymous Ampère's law, which relates the size of the force between two conductors to the length of the wires and the magnitude of the current. He labelled the flow of charge “intensité de courant”, meaning current intensity, and gave it the symbol “I”.

[@sokolum]

2:23 MATH 💯

[@ElectroAtletico]

The letter "I" is used to represent electric current (measured in amperes or amps) because it comes from the French word "intensité" (intensity), referring to the intensity of the current. This notation was introduced by André-Marie Ampère, a French physicist and mathematician who made major contributions to the study of electricity and magnetism, and after whom the unit of electric current (ampere) is named.

[@noobulon4334]

I see a lot of people asking why 48v and not higher, and the answer is safety considerations and standards. EV manufacturers want to minimize the amount of high voltage wiring and connections in the car so that faults are less dangerous and make it easier to work on the secondary electronics. 48v is about the limit of what you can call "low voltage"

[@tjmozdzen]

Nice short and sweet info!

[@randomyoutuberthotslayer8247]

For EVs, the auxiliary power significantly affects the range of the vehicle because the power for the auxiliaries come from the HV battery. So, a little saving in auxiliary power caused by the switch to 48 volts will have its effect on the final range of the vehicle.

[@flthecat]

I’m still confused. Why did Tesla choose 48 volt instead of 24 volt as some tractors use and if 48 is better because everything becomes more efficient, then why not 96 volts or higher? The math is easy (although I think Engineering Explained does it better) but I still don’t understand how they arrived at 48 instead of something else.

[@noobulon4334]

96v hurts too much

[@DougKirby-f5q]

Wow, back to school again it’s been a long time👍

[@DishNetworkDealerNEO]

The wiring is the big benefit. The mass reduction in the harness is one of the big reasons along with the Steering by Wire!

[@internet-of-things]

Great explaination!

[@dennislevy3603]

The letter “I” is used to represent electric current due to historical reasons. The notation was introduced by the French physicist André-Marie Ampère, who is considered one of the founders of the science of electromagnetism. In his work, Ampère used the French word “intensité” (intensity) to describe the flow of electric current, and the letter “I” was derived from this term.

[@georgelewisray]

GREAT Job Explaining !! Thanks ......

[@realvanman1]

The voltage drop across the dissimilar metals of brushes and commutator are approximately constant, regardless of current. They behave somewhat like a semiconductor in that regard. Therefore, all things being equal, the voltage drop across them is the same for the 12 volt motor as with the 48 volt motor, and therefore are four times as much power as with the 48 volt machine. Furthermore, the eddy current losses in the armature windings themselves decrease by having the windings more finely divided, ie more turns of finer wire. Further furthermore, the brushes and commutator can be smaller, and therefore have lower friction losses. Even more, the voltage drop across those mosfets is approximately constant too! So, the same rules apply to them as with the brushes and commutator. I will assure you, that those 48 volt motors are indeed more efficient. I will agree, however, that that wasn't the motivation. The ability to use smaller, lighter wiring throughout the car is a big factor, as well as, as you said, the ability to have higher powered accessories.

[@ron5948]

I think for these small motors you want to do power conversion to AC centrally and adapt number of phases and power requirements to the application. Maybe some simple frequency conversion step before the actual motor to minimize copper use in cables? Ah yes multi fibre copper cables for sure, some data others different phases separately! ??? 10:06

[@kubakubikula6618]

The symbol "I" for amperage comes from the French word "intensité," which means "intensity." This term was used by André-Marie Ampère, a French physicist who made significant contributions to the understanding of electromagnetism.

[@thomasruwart1722]

Math & Simple Accounting: There are three kinds of people in the world: those who can count and those who can't. That's my two scents💩💩😁 Great video, BTW! Thanks!

[@jamesengland7461]

😂

[@diraziz396]

Thank you. very clear.

[@charlesrovira5707]

*_Very_* informative. Thanks.

[@rjv2395]

I am not an engineer, but have designed greenhouses and growrooms on 48V grid. you gave a good explanation, but maybe skimmed over the major point. 4X V allows -4X I. when the amperage decreases, the wire size decreases, the safety factor increases, cost decreases. you did say this, but maybe your emphasis was more on the features they could offer with 48V instead of what allowed them to offer those features. I got it, the mosfets and all other components can be downsized. but I knew that answer already. not sure if someone unfamiliar with this would catch it. but tks, great vid. how long before other manufacturers start the adoption? still waiting for a vide on axial flux motors, are they worth the hype?

[@zorkpl]

The letter “I” is used to denote electric current (amperes) due to historical and linguistic reasons. It comes from the French phrase “intensité de courant,” which means “current intensity”. In physics and engineering, standard letter symbols are often used for consistency and global recognition.

[@Rich-on6fe]

That's a funky board layout.

[@moreboost]

Lol I can't wait for Sandy's educated viewers to reply lol we all learn together! Thank you for the video. Is this a test to see if anyone is listening?

[@noobulon4334]

I'm not listening

[@maerklin29800]

But STILL there are LESS electrical losses from the energy source TO the 48 V motor at the same power right? But the electrical losses INSIDE the motor are the same?

[@logenmattsen]

The letter “I” is used to represent electric current (measured in amperes) because it stands for “intensité de courant” in French, which translates to “intensity of current” in English.

[@kerrygwebster]

Nice breakdown.

[@WentzCraft]

What creates more heat 12 volt or 48 volt? Heat generation is also a loss through inefficiency that may not be equal mechanically.

[@kazedcat]

In the power window example the heat generated is the same. If that device was redesigned to work at 4X more RPM to compensate for the 1/4 reduction in current then 48V will produce less heat.

[@rom-p73]

This is ABSOLUTELY NOT how it works. The current through the motor does NOT only depend on resistance of the winding. It also depends on the inductance of the windings, which in turn depends on the mechanical power the motor is outputting. The faster the motor is turning, the bigger is the second factor. Increasing the supplied voltage decreases the current that is required to produce the same electromotive force in the motor, which reduces Ohm's losses. Which makes the motor more efficient, or more powerful, or both (depending on the winding)

[@grekiki]

I thought current to produce a certain torque only depends on KV and not on supply voltage before ESC.

[@Brocknoviatch]

Is 48v the point of diminishing returns? Is 96v better? Why stop at 48v?

[@noobulon4334]

96v hurts too much if you touch it

[@Brocknoviatch]

@@noobulon4334 there’s plenty of wires you can’t touch in an electric vehicle!

[@noobulon4334]

@@Brocknoviatch well, I think the minimum number of wires you can't touch is like 8

[@GeoFry3]

48v seems to be popping up across industries. Solar, battery storage, and POE (networking) are both moving to 48v. I wouldn't be surprised to see all lighting and small devices (USB) in a house in the next decade to be moved to 48v DC.

[@cristerhelin8532]

When using "V" for voltage (measured value) we (Europe) normally use A for Ampere (measured value). Otherwise, when we use "I" for current we use "U" for voltage as nomination letters. We never mix "V" and "I" or "U" and "A". Ohms law is normally written U=I×R. The most common reason for raising the voltage and thereby reducing the current is not at all about electric efficiency but to be able to use thinner wires, which means lower cost and lower weight. . So a motor for 48V is using windings with copper wires that are 1/4 area (higher resistance) compared to a 12V motor. Hence they will fit in the same rotor. This is also why there is a huge advantage to have a 800V drivetrain instead of 400V in an EV, and I think we will see 1200V and maybe 1600V drivetrains coming. The power electronics are already there to be used, I think it is more a question of regulations.

[@ssjung200]

Hi Sandy! written on the PCB board.

[@537203]

Great video. Thanks for explaining it in such course terms with the actual components visible. Now where can I buy a 48v winch? Lighter switches and cable runs for powerful accessories is one thing I am excited about. (I need one on my 48v golf cart too.)

[@Ulli4Ever99]

Super erklärt 💯💪

[@JEP-Tech]

A quick Google search says: The symbol "I" is used for current because it comes from the French phrase intensité du courant, which means "current intensity".

[@Starship007]

48 volts needed for larger windshield wiper motor also

[@aware2action]

Feel the 48V is chosen based on increase of sustained total power consumption, due to new features and to combat the efficiency loss of power conversion to 12V. There is further saving in power distribution(reduced copper) and reduced size of components mosfets(for a low volt high current approach, you need mosfets with extremely low Rds ON, which are quite expensive compared to higher loss low current commodity mosfets), capacitors(needed for smoothing, storage etc) is also another one(probably Tesla identified a sweet spot in savings and reliability). Just some 💭❤️👍

[@malloott]

Great video, but it does feel like 1.25 speed = normal speed. No offence, great presenter! I for Amps originates from the French intensité du courant

[@janhofmann3499]

I watched it at 1.25😂

[@PaulTurnbull-EMfield]

I'm not offended at all. Please use the 1.25 or 1.5 speed for my videos. I'm not an actor and I'm not reading from a script. Also, thanks for answering my question about using I for current. I'm glad the Munro Live viewers can share their knowledge of the history of engineering.

[@etalon3141]

Really useful video. I saw someone talk about this in drone motors, 6S vs 4S lithium, and the take home was: doesnt help the motor much (if at all) but does help power delivery and wiring. Why the motor was not improved significantly at higher voltage I didnt understand, but I do now! They did mention slightly better winding packing when using thinner wire helping a bit, does that bear out on these? or is ultimate performance in a motor like this not really a target, unlike a drone motor where every gram and bit of efficiency is saught after.

[@BellaNash]

Small models don't have the efficiency problems of a 6000lb vehicle, motors are wound for either max power or rpm. Either way weight maximums delegate a battery size = weight per vehicle. A tiny camera might weigh a couple of grams, whereas anything heavy (ounces) can change everything.

[@BellaNash]

Should have included, the higher the gross weight the more battery is required. But a certain model size dictates the maximum battery weight overall.

[@philipp594]

The wiring can be thinner and lighter which lowers vehicle weight and kind of makes the car more efficient?

[@w3072]

good job

[@pdpcycling248]

For inductive load, shouldn't we use XL=2*PI()*f*L to calculate eqv. resistance? I have no idea why but same wattage motor, the higher voltage rating one will have better efficiency based on experiment.

[@georgehenry3384]

Higher voltage and lower current has an advantage on I^2*R losses but only comes apparent in transmission and distribution lines. For example a transmission line may supply power at 231KV to power a home at 120/240 volts. I can power an entire city with 400 amps, a typical home has a 200 amps service. The other advantage is much smaller conductor!!!

[@mikeloeser6239]

I would think they just changed the pinion gear on the motor, instead of the motor windings. Then you'd keep the advantages of 48v.

[@JonathanTamm]

just load finer wire into the armature winder and up the turns 120 volt motors in home and shed devices use similar size motors with 10 x the turns.If you just fit a smaller pinion it will not mesh without making another casting to make up for the smaller pinion or making the mating gear larger to keep the shaft spacing the same but their will possibly not be enough room for the larger gear so another housing so at least 2 changes up to 3 none of them cheap or quick.

[@Miata822]

Good video.

[@MunroLive]

Thanks!

[@MRSketch09]

Hell this video was amazing, but so were the comments. Glad I watched it. You'd think more automobiles mfg, would have gone to 48 volt systems, if they worked better? I mean I'd like a quick responive airride system..

[@ronten-hove2777]

André-Marie Ampère was French. The phrase he used for electrical current was "intensité du Courant", which he abbreviated as "I" in formulae. Later, because the letter "I" was already taken, electrical engineers used "j" for the square root of -1, unlike mathematicians, who used "i" (for imaginary).

[@arya_jahan98]

The Hummer EV has 4-wheel steering yet is on the same 12V architecture, so the argument to switch to 48V isn't satisfactory.

[@JonathanTamm]

US still has 12 volts on real trucks the rest of the world has 24 volts GM in the US is not the peak of automotive technology I worked at GM in the 80s they were crying about the Japanese overtaking them and they are still dragging their heels they would still use 6 volts if they could get away with it.

[@stirlinggreer]

Also wondering if they want to be able to make Solar systems that can DC charge the vehicles without inversion. (most quality panels are 48V by default)

[@abid583ind]

The mosfets are also in the pennies cost....