YTread Logo
YTread Logo

The Truth About Tesla Model 3 Batteries: Part 2

The Truth About Tesla Model 3 Batteries: Part 2
Welcome to another Two Bit da Vinci video, this is

part

2 of our Series on the

Truth

About

Tesla

Model

3

Batteries

. First, we need to correct something from

Part

1. When we showed prices per pound, we accidently divided the kg price by 2.2 instead of multiply. Here are the corrected prices. While our unit conversion mishap didn’t lead to the loss of a $125M Nasa orbiter or anything, we do feel bad nonetheless. Rest assured we’ll do better going forward! Ok so in

part

one we discussed the raw material supply chain, and the battery cell manufacturing of

Tesla

’s 2170 cells. Today we’re going to pick up here, and discuss how

Tesla

takes these 2170 cells, and create their world class battery pack modules. First, you always want to start with

batteries

in parallel that form a brick. This brick on the long range edition contains 46

batteries

, while the base

model

will have 31

batteries

. This is so that any single failure in a battery won’t affect the core voltage of the brick. You’ll just lose that amount of capacity and range.The next brick is inverted and added to the first brick in series. All

batteries

that form a brick, are attached in parallel via a bus bar. You’ll notice that a thin filament is actually all that connects a battery to this bar. The reason is because of its thin gage, it actually acts as a fuse. If too much current flows, either during charge or discharge, it’ll overheat the fuse and break. This will remove the battery from the rest of the brick...
the truth about tesla model 3 batteries part 2
and isolate it from any further damage, or potential thermal runaway events. For further protection,

Tesla

’s 2170

batteries

have 3 very small holes that act as vents to discharge the electrolyte to prevent pressure build up, and possible explosion. There is also a “blue goo” which is added to further add stability to the pack and prevent cascading failure. Speaking of thermals, we mentioned one of the benefits of small cells is the ability to better cool each battery. That’s where the cooling manifold comes in.

Tesla

has a patent (US20110212356A1 (https://patents.google.com/patent/US20110212356A1/en)) for a cooling manifold assembly for their battery packs. The cells are covered in a thermal interface material, which is a poor electrical conductor, but a good thermal conductor, that allows good contact between the Aluminium battery casing and manifold. A water and glycol coolant mixture is pumped through this manifold, where heat from the

batteries

can be transferred, just like liquid cooling for your PC, or a conventional liquid cooled gas engine. What’s special about this design is the wavy groves, which allow maximum contact between battery cells above and below the manifold, with minimal increases in flow drag. In the case of the BMW i3’s prismatic

batteries

, or the Chevy Bolt’s pouch

batteries

, this cell by cell cooling isn’t very easy to achieve. One limitation to this design is that the coolant will be colder when it first enters, and warmer near the...
the truth about tesla model 3 batteries part 2
exit, leading to a slightly uneven cooling of a few degrees. This is why the wavy design, that doesn’t reduce flow rate substantially is so important. This means the warm coolant can be pumped to radiators more quickly. Keeping

batteries

cool as they charge and discharge is one of the most important factors in safe operation, and also maximizes the usable life of lithium ion

batteries

. You’ll notice there’s no radiator on the front of a

Model

3, like in petrol cars, and that's because EVs don’t need that level of cooling for the motor. However, look lower on the front bumper, and you’ll see vents that house the battery thermal management system and powertrain radiator. These motorized vents can open and close to minimize air drag, while also providing air flow for the radiators when needed. This can only drop temperatures to level of the surrounding ambient air, but for especially spirited driving, super fast charging, or very hot days, the coolant can be ported through the air conditioning system through plate heat exchangers for even better cooling.

Tesla

’s

Model

3 has a new simplified 4 battery module system. Weirdly they’re not all the same size, with the the outer modules featuring 23 cell groups, while the two inner modules feature 25. Again this is the beauty of a small cell design, that gives them this sort of flexibility. A recent teardown of a

Model

3 Battery pack by Jack Ricard, reveals that each cell brick is 46

batteries

in parallel, mated to...
the truth about tesla model 3 batteries part 2
either 23 or 25 other bricks in series. This means an extended range

Tesla

Model

3 has 4,416

batteries

, and weighs in at roughly 1,050 lbs. So the

Model

3’s entire battery pack has a capacity of roughly 80 kWh, and a density of (1054 lbs = 478kg _____ 80kWh = 80,000 Wh / 478 = 167 W/kg Remember the 5 minute battery swap concept Elon showed off a few years ago? Where a

model

S could pull in have a robot swap battery packs in less time than a petrol car could fuel up? Well it appears that idea is dead, because the design of the

model

3

batteries

, with their solid aluminium bottom plate, won’t allow this functionality. But that’s why

Tesla

has been investing in DC Fast chargers, and their NCA chemistry, combined that with the brilliant cooling system and air conditioning exchange, means

Tesla

Model

3s should charge quickly with few thermal bottlenecks. Along with their cooling system, the second factor is

Tesla

’s world class Battery Management System or (BMS). The BMS tracks the voltage on the cell level, to ensure that the

batteries

charge and discharge evenly. It also monitors battery brick temperatures via strategically placed thermocouples, and is something

Tesla

now has over a decade of experience with. There are individual BMSs for each of the four battery modules. One of the great concerns with large lithium ion battery packs, is that a few individual cells don’t discharge with the rest. Then the system reports low range, and accepts a charge. But when this near...
full battery accepts a charge, its voltage will start to build up and cause degradation and could even explode. The BMS monitors this to ensure all the cells are fairly uniform, and they have further protection with their individual battery fuses. Jack Rickard reported voltages within a hundredth of a volt between all the bricks in a

Model

3 Module. That’s pretty impressive, and a true testament to this crucial system in the

Tesla

Model

3 Battery pack. On the back of the battery system you’ll notice a small hump.

Tesla

lovingly refers to this as the “Penthouse.” To further optimize the manufacturing process for the

Model

3, All battery related systems for the entire car are housed in this com

part

ment. In previous

model

s like the S, the various AC-DC inverters and other electronics required for safe battery operation were spread around in various areas throughout the car. But now, for the

Model

3, this entire pack and Penthouse is fully assembled at the Gigafactory, and shipped to Fremont, where they can go into

Model

3’s more quickly with less assembly hours needed. This is a small innovation, but it really pays dividends when mass producing

Model

3s. So another question we always get is, my cell phone battery only lasts about 2 years before it starts going bad, surely

Tesla

s must have the same problems. The answer, luckily is no, and the reason is two

part

: 1 most electronics like laptops and smartphones use LCO or Lithium Cobalt Oxide) chemistry because they...
provide high density, while suffering from a tradeoff of a lower cycle lifetime. Most people only keep cell phones for a few years, and the manufacturers have decided that being small and energy dense is more important than being long lasting. The second reason is that laptops and smartphones are charged to 100% and also allowed to discharge to 0%. This extreme state of charge and depth of discharge can really degrade the battery quickly. Again the the case of your smartphone, it's more important that it last 12 hours and not 10, then it is to last 4 years instead of 2.

Tesla

Model

3’s will help you charge and discharge at the best level for longevity. If you want to make your

batteries

last as long as possible, charge to about 80-90% capacity, and only discharge to about 30%. If you’re going on a long road trip, of course you can charge to 100% on occasion, but when your commute is less than your range, you should always try to charge to the recommended level. In the

Model

3 interface, the one user adjustable setting is the state of charge meter. A slider allows you to adjust how close to 100 percent you want the car to charge to. Just remember to leave this where recommended, unless you know you have a long trip ahead. Remember that the voltage of a battery changes based on its charge. At fully charged, a 2170 cell has a voltage of above 4 volts, while fully discharged, only around 3. Also, if you remember from

part

1 where we talked about the hybrid graphite anode...
expansion and contraction from charged to discharged, it is again best to avoid the extremes. This user adjustable charge level has led to some confusion and questions that we want to clarify. We’ve been asked if the the base

model

3, and the extended range car, actually have the same battery packs, and based on price, the added range is unlocked via software. This question arises because there were reports that

Tesla

unlocked extra range for people in Florida who were running away from Hurricane Irma. The story goes like this, back a few years ago,

Tesla

was selling 75 kWh battery packs at a lower price, and locked the car’s charge level to only 60 or 70 kWh. The idea was this made a cheaper car possible, and also presented

Tesla

an upsell opportunity. You have to remember they weren’t making

Model

3’s yet and they were getting creative about selling cars. So with unlocking the max range option, or in the case of Hurricane Irma,

Tesla

is able to flip a digital switch, and set the car’s state of charge meter to maximum. But don’t worry there’s no such trickery in the

Model

3. The

model

3 has two distinct battery packs, one with 50 and one with 75 kWh of usable capacity. There’s no software magic at play here. So with amazing battery cooling, a state of the art Battery Management System, and 10 years of experience, how long will your

batteries

last? Historic

Tesla

Battery data suggests 95% range after 50,000 miles, and 90% after 150,000 miles. That means your...
310 mile extended range

Model

3, will travel 279 after 150,000 miles. That’s after 11 years of driving at 13,500 miles a year. But the news gets even better, because that historic data includes older battery packs. Our good friend Ben Sullins over at

Tesla

nomics is a data scientist and has put together some real world numbers from

Tesla

’s around the world. If you haven’t seen his channel, we highly recommend you check him out! He’s taken the source Google Sheet, which has been filled out by

Tesla

owners around the globe, and presented it in a great visual representation. Links to the original Google Sheet, and Bens site, will be provided in the video description. (https://docs.google.com/spreadsheets/d/t024bMoRiDPIDialGnuKPsg/edit#gid=1710185683) (https://

tesla

nomics.co/what-is-the-lifespan-of-a-

tesla

-battery-and-how-long-will-it-last/) Ben’s website allows you to sort by kilometers or miles, or charge cycles, or vehicle age, and filter by different regions. You’ll notice that all the data fits pretty well, and the almost all the vehicles seem to fit into the 90% range left after 150k miles curve. There are a few outliers that have dropped to around 85% remaining range after just 30k miles, and that’s what we wanted to break down next. We’ve read a lot of articles about some

Tesla

owners needing battery pack replacements and so we thought we’d break out the cars that needed new battery packs from this data. Filtering in this way, reveals that about 6% of the...
cars needed a battery pack change, either for some faults, or possible excessive loss in range. What we found was interesting, almost every

Tesla

that needed a replacement battery pack, was manufactured in 2013 or older. Cars that were built more recently, don’t seen to have any issues, based on this telling, but limited data. Furthermore, every single one of the cars that needed new

batteries

, had battery swaps within 8 years and 100k miles. (Show visual for standard battery and extended warranty). This, we believe is the most telling information of all.

Tesla

is going to have a few bad battery packs, it’s almost impossible to totally eliminate. All it takes is a few bad cells, a few bad solder joints, or bad sensors to cause potential issues. This has to be the single biggest downfall of

Tesla

’s 2170 cell strategy. When you have to create an array of over 4000

batteries

, some errors are likely to arise. But here is the good news, if you do have a faulty battery pack, you’re likely to catch this well within your warranty period.

Tesla

knows this, and provides the warranty in accordance. Also, their process, and mastery is only getting better and

Model

3 owners are likely to have the best results of any

Tesla

to date. Do keep in mind that petrol cars aren’t perfect either. We have the Lemon law to allow owners to fully return cars that prove to be problematic. There are also thousands of reports of cars needing new transmissions, or engines well below 100k miles. At...
the end of the day, its an engineered and manufactured product, and as humans, we’ve never made anything perfectly, and never will. What’s more important is that rates of failure are low, and that companies rise to occasion with great warranties.

Tesla

is doing well on both accounts. The next biggest question we get is about cold weather performance. So why is cold weather such a concern for Evs? Well the reaction happening inside those lithium ion

batteries

is a chemical one, and one that is dependent on environmental factors like temperature. So the battery thermal management system is crucial here as well. One thing to note, is that for the

Model

3,

Tesla

has ditched the dedicated battery heater. Instead they have opted to warm the coolant via waste heat created by electronics and powertrain systems. That includes the electric motor and the DC-AC inverter. So the battery system and the powertrain system both share the same coolant loop. This architecture makes the

Model

3 Coolant system more simplified, and efficient than previous

model

s. Unlike cooling a battery, where coolant is past through either the air conditioner stack heat exchanger, or font radiator, when heat is needed, the coolant is pumped through the powertrain cooling system. You might be wondering what happens when the car is parked and not running? It turns out, it’s the same process, only now, electricity is intentionally wasted in the powertrain and inverter, in the interest of creating heat. This...
heat is gathered by the coolant, and pumped through the

batteries

. Your

Model

3 can be programmed to keep the

batteries

warm in this way, until the charge level drops to 20%. But heating the

batteries

in the cold isn’t the only EV downside. There’s also the passenger cabin to contend with, and this is where petrol cars have an odd advantage. Internal combustion cars are so inefficient, that about 80% of the gas you burn is actually wasted as heat. This waste heat makes heating the cabin incredibly easy, and is a weird advantage that EVs just don’t have.

Tesla

’s electric AC motors are between 80-90% efficient. So what is

Tesla

to do? They could have just put in a simple inefficient resistive heating element, like the one found in Chevy Volts and Nissan Leafs. But they actually thought about this and have filed a special patent. (US US20100025006A1) (https://patents.google.com/patent/US20100025006?oq=20100025006) Their patent describes a system where the waste heat from every system that needs liquid cooling, including electronics and powertrain, is used to heat the cabin, instead of just discarded. And they have a conventional resistive heater too, but is required to run less due to the heat pump system. Using electricity to create heat is a very expensive operation, and in most EVs in sub freezing temperatures, range can be reduced by about 50% due to heating requirements. With

Tesla

’s clever waste heat pump, your range reduction will probably be closer to 30%. So...
your 310 Mile

Model

3 will delivery roughly 200 miles of range. This figure is hugely temperature dependent, so find how cold it gets where you live, and ask the specialists at

Tesla

, to get the best information possible. Let’s put this into a little bit of context. In freezing temperatures, a lot of petrol cars won’t even start. While you in your

Model

3, will be just fine, albeit with reduced performance and range numbers. Also, you’ve probably seen outlets outside restaurants and grocery stores in places with freezing winters, for petrol cars to plug in and run a engine heating pad. This pad keeps the engine warm enough to turn over when started. In the future, when we have millions of EVs on the road, we might very well have a similar situation where EVs will plug in, to keep the

batteries

warm and charged, while you visit your destination. And in many places, these electrical facilities are already in place. A couple of things you can do to extend your cold weather range, is turn the heater down into the 60s, not run the seat heaters, and make sure to charge as often as possible. Just remember you have a finite amount of energy, and it’s up to you to balance range with comfort. Oh, and if the

batteries

are cold, that will also reduce the rate of regenerative braking. This is again because in cold weather, there’s more resistant inside the lithium ion

batteries

, and they can’t react as quickly to convert the electric energy into chemical potential in the...
battery. So when you first set off, regenerative braking will be greatly compromised, but as the system warms up, more performance and regenerative braking will slowing return. Here is some data from Canadian

Tesla

owners, showing how much they’ve driven and how much of their original range is left. You’ll see there isn’t much of an effect, and the amount of charge remaining after hundreds of thousands of miles, is pretty amazing near 90%. https://docs.google.com/spreadsheets/d/t024bMoRiDPIDialGnuKPsg/edit#gid=1710185683 Our advice, if you’re live in very cold climates, you’ll probably want to get AWD for the added traction, and also the long range battery for better cold weather range. That covers operation in cold climates, but what about storage? Is there any risk of damaging your EV if it sits out in the cold? The answer is not really. The problem isn’t in the steady state, the problem is forcing electrons and ions to flow in these cold climates. That being said, the

Tesla

Owners manual states that these cars shouldn’t be exposed to temperatures above 140F (60C) or below -22F (-30C) for more than 24 hours. So know your region, and if in doubt, ask the experts at

Tesla

before making any decisions. So with

Tesla

’s BMS and heating magic, you can rest assured knowing your

batteries

will operate effectively for years to come. If you live in a very hot climate, the information is much simpler. The BMS will keep the

batteries

at comfortable limits, using the AC...
loop if needed. Also unlike the 30% drop in rage in the cold, running the AC to cool the cabin and

batteries

, should only reduce range 5-10%. So let’s wrap this up, by reiterating a few points: 1.

Tesla

is about to mass produce EVs and lithium ion battery packs at scales never before seen. In response to their success, other established automakers will increasingly build EVs as well, and this is going to put incredible strain on the battery raw material supply chain. A study done by UC Berkeley in 2011 states that just with Lithium reserves already on hand we could produce 1 billion 40 kWh battery packs. If

Tesla

packs are twice that size, that’s still 500 million cars with just the reserves. Other materials like Cobalt and Nickel are going to get increasingly critical, and the future is less certain. Everything has a cost, and while

Tesla

’s don’t pollute directly, stay tuned for a future video on how clean EV emissions truly are, they do have other environmental costs. As an engineer, I wish there was an easy answer to all of this, but sadly in the real world, things are rarely ever that simple. A pure EV future will, at current technological levels, require large scale mining operations of some rather exotic materials, in some conflict zones around the world. But that is why brilliant chemists are working around the globe on new battery recipes with lower environmental impact and greater performance. We’ll need continuous Lithium ion battery enhancements, but...
we’ll also need a crazy game changing energy storage advance that will finally once and for all sound the death knell for the petrol car. There are future technologies like solid state

batteries

, that will become mainstream, and who knows maybe something else we’ve yet to even dream up. But it’s a bit of a chicken or egg situation, where battery research is small because EV sales are small. EV sales can’t increase until battery research and development increase. So

Tesla

decided it was done waiting around, and took matters into their own hands.

Tesla

has already started to steal sales from premium cars like the BMW 3 series, and will only continue to do so in the future. They have moved this gargantuan industry forward, against such heavy inertia, and we can safely say, the future, is proving to be most exciting indeed. Thank you so much for those of you, who’ve made it all the way through both

part

s of this video! Thank you to all our new subscribers, and we wanted to also let you know about our Patreon page. We’ve spent over 100 hours researching for this 2

part

series, 100 hours of 3D

model

ing and rendering, and another 30 hours in video editing. This is incredibly time consuming, and we’re doing it at the cost of sleep after our day jobs. It’s simple really, we want to make more content for you, but we need your help! If you kinda like us, we hope you’ll hit that thumbs up and subscribe. But for some crazy reason, if you really LOVE us, check us out on...
patreon and consider becoming a Patron. If we’ve helped with your

Tesla

Decision, we hope you’ll consider using our

Tesla

Referral link. If you don’t want a

Tesla

, or have further questions about all of this, that’s fine too! Whatever questions you have, you’re probably not alone. We’re two bit da vinci, thanks for watching!