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 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 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 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 compartment.
In previous models 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 Teslas 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 Teslanomics
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://teslanomics.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 models.
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 parts 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 modeling
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!
