Understanding the Bolt EV

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Prof. Kelly was one of the first videos on YT that made me understand Toyota's planetary gearset hybrid transaxle in detail. He also goes to disassemble other popular transaxle & transmissions like the ZF 8spd, ZF 9spd, Honda 5AT, Lexus 8AT etc.

His videos are LENGTHY, but if you have time to waste because of lockdown, it is very educational to a gearhead.

👍︎︎ 65 👤︎︎ u/Trades46 📅︎︎ Dec 07 2020 🗫︎ replies

This professor and program are fantastic, Im so glad they take the time to upload to YouTube.

👍︎︎ 24 👤︎︎ u/EC_Approved 📅︎︎ Dec 07 2020 🗫︎ replies

As a soon-to-be-graduating ME, this guy is amazing. I wish I'd discovered him sooner. He's able to break complex things down so well.

👍︎︎ 20 👤︎︎ u/KypAstar 📅︎︎ Dec 07 2020 🗫︎ replies

Who's gonna have to be the first mechanic to tell someone the oil pump went bad on their EV. "OH SURE PAL"

@11:30

👍︎︎ 15 👤︎︎ u/the_last_carfighter 📅︎︎ Dec 07 2020 🗫︎ replies

This guy is amazing. Thanks for posting this!

👍︎︎ 9 👤︎︎ u/Blergzor 📅︎︎ Dec 07 2020 🗫︎ replies

I love this channel.

Particularly I like how straightforward he is. No clickbait or sensationalism. Just proper education.

👍︎︎ 17 👤︎︎ u/BuckTheFuckNaked 📅︎︎ Dec 07 2020 🗫︎ replies

Every video this guy makes is pure gold. Watching him tear down the bolts transmission/motor assembly and reveal that it has only four or five moving parts.... Beautiful.

👍︎︎ 4 👤︎︎ u/redalexdit 📅︎︎ Dec 07 2020 🗫︎ replies

Can he explain Tesla

👍︎︎ 3 👤︎︎ u/Yojimbo4133 📅︎︎ Dec 07 2020 🗫︎ replies
Captions
Hello everyone, I am Professor John Kelly  and this is the WeberAuto YouTube channel.   I am honored to be a speaker at your event this  year in 2020 and I've been asked to speak about   the Chevrolet Bolt EV. So sitting right behind me  here is our 2017 Chevrolet Bolt EV that belongs   to our automotive department and I've shot many  videos and spent many many hours disassembling   this car and putting it back together I was so  impressed by this car that I bought one of my own   and my wife drives it every day it's a 2019 as you  can see here in this photo the Bolt EV is a very   impressive car and the price of these cars has  come way down they've had a few hiccups as far as   a few little troubles here and there as any brand  new car design would but I'm here today to show   you the basics of the Chevrolet Bolt EV as far  as the power train electrical cooling battery   everything that makes this vehicle move down  the road and I think you'll be impressed also so   let's start with what actually makes this  car move down the road and that is the drive   unit assembly, it is not a transmission it is  a combination of an electric motor and a gear   reduction unit that we will look at here next okay  when we get right down to the heart of what makes   the bolt EV move down the road it's this electric  motor right here this is a permanent magnet   synchronous AC motor and it has 150  kilowatts of power and 360 newton-meters   of torque, it has a maximum rpm of 8810 rpm as you  drive down the road it is housed inside the drive   unit underneath the vehicle and that drive  unit includes these pieces right here   as far as rotating mechanical moving  parts inside the vehicle so we've got   the motor. the rotor of the motor right here the  stator is in the housing of the drive unit but   this motor turns a drive gear right here and this  drive gear has 35 teeth and that drive gear turns what general motors calls the main shaft and  it has 73 teeth right here and 21 teeth right   here so this gives us a gear reduction of  a little over 2:1   and then this is the equivalent of the  final drive pinion gear on any rear axle   where we drive 71 teeth of the  ring gear of a normally open uh   differential of an open style differential so  we have three major pieces here the drive motor   the main shaft and the differential case  with the ring gear on it and so if we turn   the rotor 7.051 revolutions we will get  one revolution of the ring gear for the   driving of the tires and wheel assemblies  because they are connected directly   through the side gears so here's a  side gear output shaft and it has the cv shaft going to the driver's side  that splines into it just like that and then on the passenger side reaching all the  way through the center of the electric motor   to the other side gear in the open differential   we have the left-hand output shaft  and the passenger side cv shaft to drive the right front tire  and the left front tire so   left front right front as we rotate this one  single electric motor rotor we turn the main shaft   it turns the differential case and through  the side gears we drive the left and right   front tires now that that is simplicity that  is amazing this electric motor takes place of   a typical internal combustion engine so we have  one moving part right there and then these this   gear reduction unit right here that is also  inside the same housing underneath the   the vehicle in the front there just has  this gear reduction unit to give us a 7.0518   to one gear reduction so no automatic transmission  clutch packs no shifting it's just a direct drive   gear reduction unit and most electric  vehicles have something similar to this some of them use a planetary gear set for gear  reduction but the majority of the ones I have   seen use this style of gear reduction, not all of  them have the shaft going right down through the   middle of the rotor some of them they're offset  like on the teslas but we're here to talk about   the Bolt EV and so this is what moves you down  the road everything else underneath the hood   and the battery underneath the car  all those parts are there to make sure   that we have power routed to the motor to give us  the proper rpm and the proper torque acceleration   deceleration regenerative braking and so on that  we need while driving down the road and then we   also have the rest of the vehicle which runs on  12 volts so we still have to have a 12-volt system   and there's a conversion from the high voltage 400  volt system down to the 12-volt system we call it   but it's really somewhere around somewhere around  14 volts so let's take a look underneath the car   at the housing that this goes in it's called the  drive unit it has the motor on one side the gear   reduction on the other and then we'll start  looking at the controls for making this motor   move forward or backward if we want  to back up so let's go do that next okay we are over underneath the 2017  Chevrolet Bolt EV that our shop owns and   I want to show you the drive unit and a few  other things that are here under the car while   we've got it lifted on the hoist so the first  thing let's take a look at the drive unit itself okay from right here we have a left motor mount  and right over here we have the right motor mount   this section right here these two coolant hoses uh  to the back right here this is the drive unit this   side of the drive unit right here contains that  electric motor this section right here contains   the main shaft and the final drive unit and our  axle shafts cv shafts going out uh the side um   these two hoses right here are coolant hoses we  have an inlet on the left outlet on the right the   coolant comes in goes through some channels and  there is transmission fluid the general motors   Dexron hp fluid right above that transfers  the heat into the coolant and then it moves out   I have one of these drive units on a  stand here let's take a look at it oh   before we do take a look at it there are two  drain plugs one right there one right here   this drain plug drains the fluid over here on  the gear side this drain plug drains the   transmission fluid on the electric motor side they  are there are passages and openings that connect   the two together but if you want to fully drain  it, you have to remove those two plugs and then   there's another plug right up here that is used  for uh fluid level checking so you add fluid   add another plug up higher there until fluid  comes out of the hole over there there's a special   procedure to check the fluid properly there's an  electric uh pump that needs to be turned on with   the scan tool and a few other things to make  sure that the fluid level is set correctly   all right so let's take a look at the drive  unit on the engine stand that I have here   okay this is a drive unit just like the  one that we have in the vehicle here   I want you to see that it's tipped up 90 degrees  this is the bottom of the drive unit in the   vehicle but the way the holding fixture holds it  it tips it sideways for service work so here's our   coolant inlet and coolant outlet hoses remember  we just looked at those underneath the car   right here on the front of the drive unit is the  electric air conditioning system compressor and   it's high voltage cable here okay right here on  the passenger side of the drive unit we've got   the fill plug and this is kind of hard to reach  from underneath the vehicle but that's where   you're supposed to put the fluid in I suppose you  could put it in on the fluid level check plug   area but this is the official field plug we have  an internal mode switch electrical connector here   on this side also okay here on the driver's  side of the drive unit we have the electric   oil pump this is a 12-volt oil pump and  then if we look at the top of the drive unit   we have the transmission range selector actuator  so there's actually this gigantic electric motor   assembly with gear reduction that moves a piece  of shift linkage to move a shift selector inside   the transmission for when you change your  your gear shifter from parked reverse neutral   drive and low now as we saw on the bench  over there the transmission does not shift   now as we saw on the bench over there this  drive unit does not shift this is you could   consider this a one-speed transmission but it has  an internal mode switch which is a feedback to the   computer that controls the electric motor telling  it whether or not you've selected reverse now   that seems like kind of a silly way to do things  because you would think they'd just read it off   the shifter but it's read off of the internal mode  switch and the actuator here, it has no mechanical   connection to the shifter in the vehicle so  it's kind of a strange setup   it is possible to get locked into park if there's  a malfunction so as this shift actuator moves this   linkage back and forth it actually can engage  the parking pawl or disengage the parking pawl   besides rotating an internal sensor to determine  whether or not you've selected reverse or drive or   low also on the top of the case here we have  a transmission oil sump cover where this 12-volt   pump off to the side pumps fluid up into the top  there and then it drains down and cools the stator   windings inside of this unit for the electric  motor and then there's one more electrical   connector over here and that's for the resolver  which measures the speed direction and   position of the electric motor rotor and there's  also a temperature sensor inside of here and then   one last thing that you can't see is there's  actually a fluid filter in here that is not   serviceable there's no recommended service date or  interval on that but the service manual does say   if you ever take this apart you should change  the filter when you put it back together   so this is the drive unit this is the equivalent  of the engine and the transmission of an internal   combustion engine-powered vehicle all  in one now as you can see right here   we have three orange cables coming off of the  electric motor and that these three go to the   inverter assembly which is up underneath the  hood that we'll take a look at here in a moment   that takes power from our DC battery underneath  the vehicle and converts it to AC to drive   this electric motor so moving from the drive  unit now to the electronics that help control   the motor that do control the motor these three  wires right here are how the power is transferred   when you accelerate and when you decelerate for  regenerative braking and then we have sensors   around on this drive unit to give feedback to  the computer that controls the transmission and I keep calling it a transmission but  it's a drive unit it's not a transmission   okay well let's take a look at where these three  wires connect next okay I told you that the three   orange wires coming from the drive unit assembly  that we just looked at went up underneath the   hood to a part called the inverter general motors  calls it the single power inverter module the spin   and I want to show you that but there are four big  boxes underneath the hood that we need to look at   plus one more off to the side here that heats  the coolant going into the heater core to warm   the passenger compartment so in all there  are five big boxes here underneath the hood   and we can see the top of a power distribution  module underneath that is the inverter assembly   that we just talked about off to the right  here is the dc to dc converter that takes   our 400 volts and steps it down to around 14  volts to charge our 12-volt battery over here   and to supply power for the rest of the vehicle  to run on because the rest of the vehicle other   than the powertrain that we've looked at here  the drive unit and air conditioning compressor   and some of the heaters are all 12 volt and  then underneath that dc to dc converter is   the on-board charger module so that when you  plug in your charge cord to the side of the car   it has to convert the ac power from the wall into  dc in order to charge the battery underneath the   vehicle well I have all five of these pieces over  here on the workbench so let's go take a look   at those now okay as we just saw under the hood  over there we have four big boxes and one other   box off to the side that we need to discuss  we're wanting to see how does the power get   to the drive unit so the way the power gets to the  drive unit is we start at the high voltage battery   underneath the vehicle and that battery has a  connection to this high power distribution module on the back right here and then it splits up and  supplies power to the rest of these boxes and also   a connection to the dc fast charge connector on  the side of the vehicle if you have dc fast charge   but underneath that and fed power from this is the  single power inverter module or just the inverter   this inverter receives power right  here on this electrical connector   from the distribution box up here dc and  then on the back here we take off the plug there are our three-phase cable connections so  those three wires on that drive unit connect   right here so we have DC power coming in from the  battery the inverter changes it to an ac signal   to drive the motor while we're accelerating then  when we decelerate the motor becomes the generator   feeds three-phase power back into the inverter  assembly where it runs it through a rectification   process and feeds dc power back to the rest of the  system and to charge the battery for regenerative   braking anytime you slow down and provided  there's enough room in the battery to accept   it but it could also be used by other parts on the  vehicle other high voltage parts that need power   all right this inverter assembly has two coolant  hose connections right here on the front and is   liquid-cooled it has uh it's part of the  power electronics coolant loop underneath   the hood and there are three different  reservoirs for coolant under the hood   this is one of them or this is part of one of  them all right so this is the inverter assembly   it has a low voltage connection  right here for communication with   external computers but this is what drives the  electric motor inside of that drive unit okay   this power distribution module also feeds power to  the dc to dc converter right here general motors   calls it the accessory power module and I want you  to notice right here I bought this one off of a   wrecked vehicle in a salvage yard it has the  battery positive terminal right there so we have   battery positive output our charging system  output this would be the same as an alternator's   B terminal the feeding the battery this is our  ground right here which the entire housing is it's   case grounded but that is your ground cable that  goes over to the battery this is your positive   cable that goes to the battery this is the dc  to dc converter it takes in 400-volt power from   the battery steps it down to 14 volts right here  notice it is also liquid-cooled and has a black   low voltage connection there for communication  and control with other modules on the vehicle   so if you look directly under the hood  on the right-hand side you will see this   accessory power module as general motors calls  it or dc to dc converter which is what it does right there under the hood now underneath this  is this next box that we need to talk about this box is the onboard charger module assembly  the OBCM and the onboard charger module is used   when you plug in your j1772 charge connector  or whatever charge connector you have   based on what country you're you're living in but  we have high voltage ac come in right here on this connector this is a, we've got  a four-pin connector in there   so one here in the United States that's  between 110 and 240 volts and then   we have an output from the onboard charger module  of 350 to 400 volts to charge the high voltage   battery under the car while you've got that  charge connector plugged in so so high voltage AC   in and high voltage DC out here's our black  electrical connector for communication   with other on-board devices, this also gets  hot and needs to be cooled while charging   this is only used when charging with an external  charge cord using ac voltage if we're using a dc   fast charge this module is totally bypassed and we  go directly through the power distribution module   we have power come in right here go  right back out and down to the battery   to charge it more quickly not  used at all for dc fast charge   okay so those are the four boxes that you  see under the hood and these four boxes sit on a bracket right on top of that drive  unit assembly that we just looked at so when   you open the hood on the Chevrolet  Bolt EV and you see these four pieces you   know just underneath it is the drive unit with  the electric motor and the gear reduction unit   all right now off to the left under the  hood we have the cabin heater control module   or coolant heater for the uh heater core  so we have an uh an inlet and an outlet   I thought I had those marked but oh here they  are in on this side out on this side we have high   voltage DC power from the distribution block right  here and then can communication line right there   and this is a 7500 watt or 7.5-kilowatt heater  and this is a ceramic style heater ceramic element   heater so this is another box under your hood  it's over there on the passenger side   right tucked up against the hood hinge  so this gets hot to the touch that's normal   the coolant reaches around 70 to 74  degrees celsius when it's on maximum all right I want to spend just a  little bit more time on this just   distribution box so let me slide these other  pieces out of the way just for the moment on this distribution module  I've taken it apart and removed   the internal pieces and then  I put them all back together   in this housing right here so what i wanted  you to see is that we have a two wire   electrical or two-terminal electrical connection  here that's the connection to the battery   or from the battery and then these two  terminals have a direct connection over here   to the output that goes down to the inverter  module then we have, notice three fuses   right there, so these three fuses feed power to  the heater assembly that we just looked at the   coolant heater that's his top fuse this middle  one right here comes out of this end connection   here and that fuses the accessory power module  right there and then this bottom one the blue   blue colored one feeds the  very end one right here which is   the heater for the battery coolant  so we actually have two electric heaters on this   vehicle one for the passenger compartment heat and  one for battery heat and when we put the vehicle   back up in the air and look at the battery I'll  show you that so we have three fuses   in this distribution block, I imagine  you can purchase those and replace them   but you're not going to just easily  do that because this cover right here   although it has a bunch of bolts going in from  the top there's two that come in from the bottom   so you'd have to physically unbolt this  undo all the electrical connectors unbolt it   and take the cover off to change those and  you should never undo any of these electrical   connectors without going through the proper safety  training and following the correct depowering   procedure to prevent yourself from getting  injured with potential high voltage situation   now also on this distribution block, we have  an input from the DC fast charge so right here I have the charge receptacle used here  in the united states where we have the   j1772 round connector five-pin connector there  and then two more pins right there at the bottom   these two pins right there connect to these  two wires that plug into the front of this   power distribution block so if you have a  bolt ev with dc fast charge it will have   a cable plugged into the front of this you'll  notice you may have noticed the one under the   hood of the car that we have does not have that i  didn't think we needed it for a training vehicle   but that was a mistake for me because I actually  um discovered later that I wished I had it   because I need to train other people on how the  the high current DC fast charge system works   so it has a lot of additional  components it's not just this cable   that are different even the internal pieces  in that distribution module are different there's an additional computer under the  driver's seat for power line communication   with the external charger, there's additional  wire harnesses there's different programming   for computers it's different yeah well  I already said different harnesses but   inside of here, there are two additional  contactors that connect these two terminals   from the DC fast charge to these two terminals  on the back to feed the battery to charge it   so we won't spend any more time we could spend  hours and hours and hours on the electrical system   here but this is just kind of an introductory portion or but this is just kind of  an introductory video to the Bolt EV   but i wanted to show you what the major parts were  under the hood so so you'll know what those are   nothing mysterious and then the  drive unit underneath and then   the only thing left that we need to look  at as far as uh major components are is   under the vehicle, we have our high voltage  battery and our battery heater and then   we've got the cooling systems the three cooling  systems to look at so let's put the vehicle up in   the air and take a look at the high voltage  battery and the high voltage battery heater okay here we are under the vehicle  the battery the high voltage battery   is this entire bottom of the vehicle this  black metal section, it goes all the way back   to the rear suspension so it starts right  here it's the width of the underbody and it   moves all or it goes all the way up to right  here so it is a very large physical battery   and it has 96 cell groups at 3.7 volts each for  358 volts nominal and 384 volts approximately   when fully charged this is a liquid cooled  battery and so if we look right here we have inlet to the battery and an outlet these two  hoses right here and the inlet comes over and   runs through this battery coolant heater so if we  want to heat the coolant going into the battery   then we turn that heater on if we want to  cool the coolant going into the battery there's a   chiller that's part of the air conditioning system  it's like a little mini evaporator that's up under   the hood it's kind of buried you can't see it  very well but that same coolant runs through that   as it does the heater but we don't  have those on at the same time so we have   a battery heater it's a high voltage heater  we have an orange cable connected to that   inlet and outlet there's a special  coolant flushing or bleeding procedure   there is a five year 150 000 mile  scheduled maintenance and there's   a lot of maintenance on this vehicle a lot of  people think it's just tires and wiper blades   no, you read your owner's manual there's a lot of  stuff including a monthly underbody car wash if   possible to help keep everything clean underneath  the vehicle so what else do we have here connected   to the battery, we have these two big orange heavy  cables right here those are the two heavy cables   that go up to the back of that inverter that then  creates the AC voltage three-phase AC voltage   to drive the electric motor in the drive unit  we have a high voltage orange connection here   a smaller connector and that is the connector  that's used when you plug in your charger   charge cable or charge cord to the side of  the vehicle um that is a low amperage charge   and the dc fast charge bypasses that little  tiny connector and comes right in on the large   connector right there are two ground bonding  wires over here to establish a common ground and   then there are two black electrical connections  over here for data communication and uh monitoring of circuits and and  feedback and so on in the battery   some of you may have heard that just recently  there was a recall for some Chevrolet Bolt EV   batteries catching on fire and the recall was  telling the customer to not charge the battery   to 100 percent to charge it  to a lower amount, there's a   video from Chevrolet that explains how to do that  using these software selections in the vehicle or   if you take it to a dealer they will reprogram the  HPCM2, the computer that controls this to prevent   a charge higher than 90 percent while they are  investigating the cause of the battery fires   it's my understanding there have just been  a few battery fires five to seven I think   out of close to seventy thousand vehicles sold but  it's that's enough to make me concerned because i   told you I own a Bolt EV and my wife drives it. I  want to make sure that she is safe and so we have   made the adjustments to only charge to 90 percent  maximum but we were all only charging to 80   anyway so I guess we'll see what happens with the  the Bolt EV battery recall whether they change the batteries or if it's a software fix or whatever  they're going to do if you are interested in   what's inside the battery I have a whole bunch of  videos on disassembling the battery and showing   you what's inside one word of caution there is a  center of gravity point right here it's labeled CG   it's there to center your lifting table so  that it stays balanced when you lower it okay all right as we finish up this introduction  to the Chevrolet Bolt EV, I just want to   talk briefly about the three different  coolant reservoirs that are under the hood   so starting back here with the heater coolant  reservoir this reservoir has a pipe that goes   straight down to a pump and then that pump  pumps coolant up into our heater assembly our   ceramic heater then it goes over and into the  heater core under the instrument panel here   to heat the coolant going into the heater core  for passenger compartment heat and then it returns   back to the reservoir itself  so it just makes one big loop   all right the next reservoir under the hood  right here on the passenger side is for the   high voltage battery the coolant loop associated  with the high voltage battery so just like the   the other reservoir there this reservoir  has a hose that goes straight down to a pump   where it pumps it to that heater that we looked  at underneath the car then it goes into the   battery comes back out of the battery goes to a  chiller assembly that's here underneath the hood   that removes heat from the coolant if it's  too hot and then back to the reservoir itself   so that is a second coolant loop on this vehicle  okay our third coolant reservoir on the driver's   side under the hood here is for what I call the  power electronics coolant loop so just like these   other reservoirs there's a hose that goes straight  down to a pump that pump then sends coolant to the   inverter assembly under this distribution block  then it comes over to the accessory power module   or the dc to dc converter then it goes down  to that box underneath that to the onboard   charger module then it goes down to the drive  unit assembly and then back to the reservoir   itself this vehicle does not have a radiator  in the traditional sense, it only has an air   conditioning condenser system so since the air  conditioning system cools the battery coolant   that heat is dissipated through the regular  air conditioning condenser assembly up front   so there is no radiator it looks  like a radiator but it's just the   condenser for the air conditioning system okay  well this has been a brief introduction to the   2017 through 20 Chevrolet Bolt EV there have  been some changes improvements from 2017 up   through 2020 but overall the system functions  the way the same way that we've described here   there are new there's a new Chevrolet  Bolt design supposed to be coming out   in a little bit larger of a vehicle uh 2022  or so I'm excited to see what that brings   with it and what other improvements there  will be there's always an improvement   with the next model year some change  that's taken place but with what I've shown you   here under the hood of this Chevrolet Bolt EV all  these individual components you could now go to   any electric vehicle and find pretty much the  same components they may not be all individual   pieces they might be combined into one piece  or two or three pieces instead of four or five   they might have hard busbar connections instead of  loose wire connections but every electric vehicle   I've ever seen has these same components just  different sizes different locations and so on   so if you can understand the basic operation  of the Chevrolet Bolt EV that really will help   you into in understanding any electric vehicle  that's out there right now and it'll help you   tremendously towards understanding hybrid vehicles  as well well I hope this has been beneficial to   you once again it's an honor to be a speaker for  your event and I appreciate that have a good day
Info
Channel: WeberAuto
Views: 361,154
Rating: undefined out of 5
Keywords: WSU, Weber State Automotive, Weber State University, John D. Kelly, Guy in Wheelchair, Professor Kelly, EV Boot Camp, Ogden, Utah, Bolt EV
Id: r37nqfnV9EU
Channel Id: undefined
Length: 40min 55sec (2455 seconds)
Published: Sat Dec 05 2020
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