I’m sufficiently disoriented at this point to scarce recall what I expected of the Tesla Model 3. For years we knew the progression was from the top down starting with very premium high margin low volume vehicles and working our way down toward higher volumes and lower prices.
This made perfect sense to me and I rather scorned the Nissan approach of taking a really lame lower end car, the Nissan Versa, and adding technology until it was quite unaffordable in an effort to produce a really lame electric vehicle for the masses. I much preferred Tesla’s top down migration as it covers a multitude of sins and missteps along the way, but also because of the upscale imprimatur it stamps on the electric vehicle more generally. My view of the mission from the beginning was that this was not a technological problem. It is about acculturation of the public to the idea and concept of electric cars. They should be shown how to DESIRE one. The actual building of one is sufficiently simple minded that a 54 year old unemployable working half days falling down drunk in yellow shoes could make a car in three months that would go 110 miles on a charge and hit 94 mph. Don’t ask me how I know.
I did not purchase a Roadster. By the time they were widely available the price had risen to about $126,000 for a two-seat sports luxury car and I just couldn’t quite get my head around all that as a personal value proposition. But of course I did indeed pony up $107,000 for the $55,000 Model S using Musk pricing metrics – that never was really about $55,000.
So it didn’t faze me particularly to cough up $56,000 for the $35,000 Model 3, using the same ElonMath I was by now accustomed to.
But I guess what I was expecting was a tamed down/toned down Model S – smaller, less power, but basically a miniS for the masses. And I was hoping the disappointments would be minimal and mostly about things I didn’t care about too much.
When push comes to shove, I do care. But it’s a mixed basket. Some things seemed actually improved – like the brilliant solution to the $400 car key thing and I was delighted with the air conditioning and heat, the visibility, and actually the performance if you must know. The interior seems easily as large and spacious as the S. And actually the weeny door geometry of the S was improved a very important have inch for ingress and egress. The car looks great and the little bit of additional range over the S is actually key to a St. Louis urban area 120 miles away. The S just won’t really get there and back without charging, and the Model 3 will. I’ve done three roundtrips with at least 50 miles remaining on the clock on my return. The 310 miles is very real if you keep it 70mph or under.
True, the ride is stiff and the controls and display screen, I’m sorry they are just comically bad. My initial experiences with autopilot, autopark, summon, and even the garage door opener have been poor. I actually view autopilot not as improved safety as Musk hopes, but perhaps fatal in even the proper hands. Autopilot is a bent arrow and it’s hard to predict where it will strike in the end. But it isn’t looking good. It’s actually CAUSED me three harrowing near misses on excellent Interstate highway in severe clear weather. I’ve been an aviation pilot for years, and rather think I drive a car very conservatively but with precision and I’ve a driving record of some 45 years now without a reportable accident. I just don’t have close calls.
This past few weeks we have received our first salvaged Model 3 allowing us to do a bit deeper dive than I was quite willing to make in my brand new daily driver. And the thot plickens most curiously.
So to give you the end punch line BEFORE the reasons why, the Tesla Model 3 is not at all a tamed down/toned down Model S. In fact, despite my personal choice of color and wheels to match my S, it simply isn’t an S at all and I’ve been viewing this car through entirely the wrong lens. Broadly speaking, it has nothing to do with a Tesla Model S at all and I can’t find any indication internally that it is even manufactured by the same company. It doesn’t even use the same LOGO on the components. The familiar Tesla T has been replaced with a Model 3 logo that I don’t even know what to make of, which kind of matches my impression of all that we are seeing within the car itself.
I don’t even know what it is but it shows up EVERYWHERE on components within the vehicle. It looks like a Mason Jar used to “put up” peaches but with a cape that has a stylized 3 on it. If anyone can explain where THAT came from I’d love to hear about it. What is it SUPPOSED to be or evoke? Peach Technology? SuperPeaches?
But the really stunning thing is that ALL electronics and technology in the Model 3 are VERY next generation with NOTHING familiar from the Model S in any way shape or form. I haven’t seen ANYTHING even vaguely Model S or X in the vehicle. NOTHING. No DNA found. And the improvement, from what I can tell at this early stage, is not at all incremental. It’s like its from another planet.
I feel like we are examining a crashed spacecraft from another world. Picture Star Trek with an annoying ping ping tweet sounding every few seconds and an overly dramatic William Shatner ever ready to make huge drama from nothing as a Tesla Model S. And Star Trek Next Generation with Patrick Stewart as the Model 3. I’m down in engineering and it just doesn’t look the same here with Jordy and Commander Data as it was with Scotty ever trying to give Kirk “more power” somehow. In the Model 3, we resolve all irresolvable issues in the final five minutes with Tachyon Waves, which we never do quite have to explain but MAN are they some hot shit.
And in a way, I am shocked. It’s as if everything we thought we knew about the Model 3 is totally wrong. And the story of this remarkable device is simply a not yet revealed secret. And with all the hoopla about the Model 3, no one has ventured anything on this at all. What are they doing over at TeslaMotorsClub forums? I was aware they were kind of simple minded, but they do go on and on and on and I would think SOMEBODY would have actually looked under the hood or something.
We’ll be looking further at a number of items in coming weeks, including inside a fascinating drive unit, an astounding charging technology, and much more. And I rather doubt I’m going to have all the answers, and mostly likely some of the answers won’t even be correct. I trust you’ll mention it in the comments.
I guess I fear you’ll not find this moving with sufficient speed. People seeking sub 4 second 0-60 times are not a patient lot generally. But generally the Model 3 technology is beyond my paygrade. Which is cool.
I’ve kind of been bored with electric cars in recent months and increasingly thinking about solar. But I face a huge learning curve on the Model 3 and that makes me all dancy and chipper again.
Inn this episode we removed the heart of the melon, the battery and took a peek inside.
In recent months we’ve been doing a lot of work on Tesla Model S battery modules and packs with an eye toward using them for Solar Energy Storage. We did develop a little control kit to use the Tesla Battery Modules and the BMS board that is mounted on them and we can scarce keep them in stock at this point. http://store.evtv.me/proddetail.php?prod=basicsmodulecontroller I rather had aspirations of starting the investigation into the Model 3 battery for a very good reason.
In all of Tesla put together since 2004, the company has made some amazing strides in initiating the conversion of our personal transportation to electric battery powered magnetic drive. No surprise that I rather favor that as a strategy. But understand that in ALL that time and ALL put together, they have sold 300,000 vehicles world wide.
Today they stand with 450,000 orders in hand, give or take a hundred thousand as the whim and the mood of the apostolic following’s mood varies, striving heroically to reach a 5000 unit per week production rate. That’s 250,000 vehicles PER YEAR. So with the X and S, they intend to manufacture more vehicles in the next year than their cummulative total manufacturing to date.
In the Q1 Analysts call, Elon was a little short with a guy asking where the 450,000 orders stand. I initially also thought it odd but on reflection, he was actually very nice about it. They are all over him as to when he’ll be able to produce enough, WHILE Tesla car sales in China have ballooned in the last year to over $2 billion representing 19% of their total automotive revenues. Musk is staring down the maw of a monster trying to eat him if he doesn’t paddle faster producing cars and here is some freaking moron wanting to talk to him about DEMAND for a car that’s never been advertised anywhere and which he can’t possibly make enough of for about five years coming NO MATTER what he does or how well he does it. At some point irony begets absurdity and absurdity ventures into moronic chant, and that’s where he was in a very exasperating moment. I’m sorry Wall Street, but you’re going to have to up your game or sit this one out. It won’t be like you’ve never missed a big move in technology before.
My point is, California drivers being what they are, it’s going to soon be RAINING Model 3 batteries in the junk yards. But we don’t know how to use them. And I haven’t heard of anybody else that does either.
So I’m going to share what we learn as we go along hoping to advance the token more widely as well. But if you notice something in the photos and descriptions, please feel free to jump in and suggest something. Remember, there ARE no stupid questions, only stupid people asking them. Note to stock analysts.
The first thing I would note is that in this vehicle, Tesla has integrated MOST of the vehicle electronics INTO the battery assembly which is put together in the Gigafactory in Nevada. The charger, BMS controller, junction box, DC-DC converter and all protection circuitry has been moved into a hump on the end of the battery termed for no apparently good reason the “penthouse”. This can actually be accessed for service by removing the back seat as it projects upwards exactly where the seat cushion is for the back seat. You would have to remove the seat bottom, a couple of braces, and then a bunch of star head screws, but it pops off and allows access to the fuses and contactors and so forth pretty readily.
The combined charger/dc-dc converter is a thorough MARVEL inside. We will be looking more closely at this in the future but it again has NO apparent relationship to any previous Tesla charge circuitry, and they squeeze 10kW of charger into a remarkably small and cool running package.
Contactors and fuses and so forth are most notable in the compact arrangement eliminating dozens of feet of expensive cabling and connections. They did add a pyro-disconnect. Picture a fuse you can blow up with a digital signal totally and most assuredly disconnecting the pack from everything in the event of say, welded contacts on the control relays. A total failsafe and kind of on the principle of an airbag detonator.
And no evidence of a SINGLE part in this assembly that has ever been near a Model S. Entirely different contactors. Of course a different charger/dc-dc converter which is now a “power conversion unit” and the BMS board is now entirely different and referred to as a “high voltage controller”.
It didn’t take long to strip this down and remove all that and we decided to learn to deal with a Model 3 battery as a solid assembly in the future and probably with another wreck. For this one, we opened the can to get right to the modules.
The modules are much larger than in the S or X. They are long narrow logs of cells with 23 cells in two of the modules and 25 cells in the other two.
The two 23 cell modules are at each edge of the pack and 67 1/2 inches long, 11 1/2 inches wide and 3 1/2 inches thick and weigh 191 lbs.
The two 25 cell modules are located in the middle of the pack and 73 inches long, 11 1/2 inches wide and 3 1/2 inches thick and weigh 207 lbs.
And of course what caught our immediate attention was the very very different battery management system boards located on each module and connected by a tiny two wire cable in daisy chain fashion and back to the high voltage control board.
I’ve been explaining battery management systems for 10 years now. It’s been a shitshow. And an annoying one. The number of BMS experts available in the world who know absolutely NOTHING of which they speak is astounding in quantity and awe inspiring in their insipid lack of comprehension as to what they know and think they know with almost all of it completely dicked up. And they pose a danger to battery owners everywhere. I gave UP trying to find one for EV’s and also gave up designing one of my own and developed survival techniques using LiFePo4 batteries without them entirely. Unfortunately, those techniques are simply impractical with the more energetic NCA cells used here and with Tesla’s packaging techniques.
The issue is that measuring battery cell voltages is deceptively simple. And unbelievably hard. And for simple minds, the simple part seems to be the part they like. One thing worse than no BMS is a really badly designed amateurish ass clown BMS that you THINK is working and controlling your charge cycle, but it isn’t, and your charger burns up your battery pack while you snooze peacefully one floor above the car in your now burning house. And then of course some times the amateur BMS’s themselves simply catch fire and find a ready fuel supply in the batteries they are attached to. And if none of that happens, the spaghetti wiring connecting the BMS to the battery catches fire. The end result is the end result. And it’s not a good outcome.
The problem is common mode voltage. It SHOULD be evident, but it apparently is not apparent to many, that the cells are in a stack that results in voltages 100, 200, or 400 volts higher than the return terminal. And while there are hundreds of circuits available to measure 3.6v or 3.2 v very nicely and with great accuracy, most of the semiconductors simply can’t stand to do so at voltages hundreds of volts above ground or above the potential of their own power supply.
And so you have a double problem in that you have to power the BMS circuitry FROM the battery cell, while measuring them, and you have to isolate each measurement from the others – usually with some sort of isolated communications bus linking them all together, or some combination of all of that. And so the very simple looking task quickly becomes a monster. I’ve known PHD level EE who have simply dicked such a thing up beyond all possible recognition and at times catastrophically.
The nature of one off EV builds is that EACH is unique and so EACH is a beta test site for something designed by someone else for something different. No possibility of harm there.
And so imagine my horror when BOTH the EV community AND the solar community began using salvaged EV batteries for their own concoctions, and generally without the BMS at all or using something designed for something entirely else?
But the economics are apparent to anyone. Half-priced lithium battery cells. This is what everyone has wanted all along. So it is GOING to be done. How to enable them to do it safely. Or at least more safely than hoping for good things…? And this in a world where MOST of the BMS designers out there suffer from delusional fantasies of competence.
Indeed Tesla has had six or eight totally catastrophic vehicle fires with essentially no known cause. But out of 300,000 cars, you know what? That’s not too bad all things considered. In fact I would hold it up as a model to aspire to.
Tesla has a multilevel engineered approach to battery application design and most of the parts are actually quite important. The first line of defense is the fusable links they use to connect each cell to the current collectors. If any cell does short out, it will immediately receive current from the brethren spirits adjacent and of such quantity that it burns up the little connecting wire. That takes it OUT of the circuit and it cannot receive further current from the pack or provide any to it. It’s been command ejected from the cockpit electrically.
They do cool the individual cells with coolant and heat them as necessary to prevent charging below 0C/32F – freezing. This is a major cause of cell death. But temperature control need not be terribly high tech.
The main BMS board and software really is about controlling contactors and monitoring high voltage safety interlocks and threats from the outside world. That’s pretty easy stuff.
But the cell stack monitoring and balancing is where the “don’t know and don’t know they don’t knows” hit the fan. Inherently, the semiconductor devices are already LESS reliable than the battery cells. And when you put them in hostile common mode voltage floats they just can’t cope. If you connect them to a bunch of unshielded antennas (connecting wires) in a noisy automotive environment, you court armageddon.
So our strategy is to handle ordinary housekeeping such as DISCONNECTING THE ENTIRE THING IF “ANYTHING” is even slightly amiss. And using the highly engineered and somewhat road proven designs Tesla has onboard for the cell stack. We want to TALK to that over an isolated bus, learn what it knows about the battery cell voltages and temperatures, and otherwise connect NOTHING to it or to the cells at all.
We’ll overlay a more configurable contactor and charging control layer on top of it. But cell stack monitoring must remain intact and unmolested.
The Tesla Model S modules feature a dedicated stack monitoring BMS board on each module, securely wired to the individual cells and two temperature sensors. This board uses a Texas Instruments cell stock monitoring board that is designed to link vertically using an SPI bus. Serial Peripheral Interface.
But Tesla didn’t use that because SPI is a bit twitchy in noisy environments. They used an RF isolation chip on each board to allow it to daisy chain the boards on a simple two wire serial connection to the master BMS board. We figured out how to wire to that isolated bus and talk to the Ti chipset over it to get all the cell voltages and temperatures and trigger cell balancing and all that.
So note well the humble philosophy of this. We are not going to attempt to design a safe BMS for you. We’re going to steal one that is already proven somewhat safER by those educated in the art, supervised by the responsible, and with a shitpot to lose if they don’t get it right. But even in theft, it comes mounted ON the module you’ve paid for, dug out of the car someone already paid for, so it’s not much of a theft. We like to euphemistically refer to it as “repurposing.” The rag and bone man’s ancient right. And even there, care is required to keep from defeating important but not readily apparent safeties.
So there really are safety issues regarding the use of these batteries, and they have nothing to do with the child minds and their preoccupation with rubber gloves and safety glasses. Feel free to fondle the end terminals. They tingle but are mostly harmless. Like a warm stove, you’ll figure all that pretty quickly. Fires and explosions are not.
The Model 3 battery stores sufficient energy to hurl a 3500 pound car with a couple of, shall we say, “well fed” adults over 300 miles. A sudden release of that energy is non-trivial.
And so we look with great interest to the BMS board mounted on the Model 3 cells. And did Tesla build on their experience and expertise with the Ti chipset? Well no. It is ENTIRELY different. Advanced, next generation stuff.
The modules feature what is basically a six foot long flexible printed circuit board with copper runs insulated by a translucent insulating layer and connecting to each “brick” or “cell” of the battery pack plus a couple of temperature sensors. There is one of these copper run “tapes” running down EACH edge of the module. The bricks or what I call “cells” is actually made of of 46 cylindrical cells 21 mm in diameter and 70mm long. They are nominally 3.6v at 5 amp-hours capacity with the 46 connected in parallel. So 3.6v x 230 Ah per cell and 25 cells for 90 volts on the long ones and 23 cells for 82.8volts This gives us a nominal pack voltage of 345.6volts at 230 Ah for a total capacity of 79,488 watt-hours. It has been LISTED at 80.5 kWh elsewhere and that COULD be true if the amp hour capacity were 232.92 Ah indicating 5.0636 Ah per cylinder. I’m good with that but we’re parsing the fine print here.
There are TWO 38 pin chips connecting to the left side copper tape and two 64 pin chips connecting to the right hand copper tape. One of the ongoing little never discussed issues with measuring cell voltage is that if you are pumping any current through the same wires you are measuring, the drop of the wires causes perturbation of the measured voltage. So whenever you “balance” these cells, you throw off the voltage measurement.
It is my belief that this generation chip has a real measurement resolution as small as 0.0022volts or 2.2 millivolts. So very very small resistance values can cause errors. Note the three tiny wires connecting to each copper land. And I guess I think we are doing cell balancing on one side of the module, while simultaneously monitoring voltage on the OTHER side of the module entirely out of the current path. This is a stunning solution and very difficult to implement normally because it means twice the numbers of wires and connections. But the flexible PCB tape approach makes this quite feasible. I’ve never seen anything like it. It’s like technology from another planet.
Our interest is of course in communicating with them. And handily there are two connectors on the board apparently just for that featuring precisely TWO pins on each connector. It would be wonderful if this were CAN but of course it isn’t. On the board you will note four modules labelled XFMRS. If you can’t spell very well, and you say it very quickly, it comes out like TRANSFORMERS. And indeed there appear to be two in each module, but they aren’t very powerful at that size.
And I am curiously drawn of course to the 64 pin chip and it is quite unusual. First there are TWO of them necessary but one of the modules has 25 cells. And so the previously largest 12cell stack monitors can’t quite cover the necessary 25 cells. Collin assures me that there are indeed 3 or 4 different cell stack monitor chips out there in a 64 pin configuraiton but I can’t find them.
Linear Technologies was acquired last year by Analog Devices for a handsome $46 in cash and .232 shares in the result. In 2008 they introduced the LTC6802 Battery Monitoring chip and has done pretty well with it. They have updated it nearly annually and have recently introduced the LTC6813-1 which they refer to as 5th generation in this series.
If we blow up our image of the chip, we don’t see much. So Collin etched off the conformal coating and did some light and angle on it with a microscope to determine a little of the logo and part number.
I did a little photoshop magic on it to further enhance that.
And so what we THINK we see there is 1722 T2-A2 PZ38984. Which there is no reference to such a number on planet. This chip is indeed from outer space.
But there is also a curious little figure on the chip. And it looks like our goofy jar of superpeaches – the Model 3 logo.
And so we’re feeling a little dead ended here. A custom chip made for Tesla. And how are we going to reverse engineer a custom chip? If they KNOW they are going to sell 500,000 Teslas, and each board has TWO of these chips, and each battery has FOUR of these boards, that looks like smells like 8 million chips. I guess almost anyone would make about anything they like and print anything on it they wanted to see for forty or fifty million dollars.
Now all of this had to be done two years ago. But last year Analog announced the LTC6813-1 in a 64 pin package. Single units are $22 a pop. But I’m guessing Tesla paid less and once it was designed, LTC had the right to also introduce it separately as the LTC6813-1. So I’m going out on a limb here to say LTC started working on this chip with Tesla before it was acquired and was allowed as part of the deal to release it as their next gen chip as long as they didn’t identify it as the same as the Tesla chip. Or something like that. I hope. Otherwise, I’m nominating a chip that wasn’t announced prior to pencils down at Tesla.
The reason I like this theory is that LTC several years ago introduced an isolated 1Mbps serial bus on TWO wires they call Isolated Serial Peripheral Interface of ISOSPI. And it uses tiny external TRANSFORMERS to provide isolation. It also steps the standard 4-wire SPI to this single pair of conductors.
So my hope is that if we use the LTC isoSPI communications protocol and the LTC6813 register commands, that we can talk to this alien beast through the “universal translator” and try to make peace between our species. As you see, I’m quite willing to throw the prime directive under the bus on this one.
As the last remaining humanoid on the Internet who COULD actually BE wrong, I have to confess I’m making all of this up out of pretty rarified air approaching lab vacuum. Hopefully some knowledgeable person will correct me in useful fashion and of course we’re open to thoughts on the 38 pin chip as well. They are very much in the daisy chain but my guess is we’ve separated the balancing from the measurement, at unusual and extreme expense and difficulty.
And so my assertion in the video and more emphatically so at this point, given the level of advanced technology and integration I’m seeing in this battery assembly, and assuming the same level of effort from the Panasonic team at the chemistry/cell level, this is the BEST most ADVANCED large scale lithium battery every produced on planet and is YEARS ahead of anything currently in work. Tesla appears to be saying to the rest of the industry, “We’ve upped our game… so UP YOURS!”
Like a 7-year-old on Christmas morning, I am in absolute DELIGHT at what we are learning about this remarkable car. The kid in me is going ape shit by what we are seeing in the charger and particularly in the motor drive unit. Across the board, this ain’t your daddy’s Oldsmobile. And I can pretty much assert that everything you THOUGHT you knew about the Tesla Model 3 is basically a miss. It’s going to be a delight, but a bit of a longer more drawn out affair to explore just what IS in this remarkable device.
Youtube teardown of 2170 cell https://youtu.be/_uKpn3zflBE