- Hi, how are ya?
We've got some good data to look at today,
but like all things in San Diego,
nothing really happens when the weather looks like this.
(upbeat lively music)
But I'm gonna do my best.
So first things first.
Gotta take Jack to school and then hit the gym.
Work on the dad bod.
(upbeat lively music)
Bye, mamma.
(baby chattering)
So, one of the things about batteries
is that they don't last forever.
And its always been a mystery as to why Tesla batteries do.
So, that's kind of the idea with this video.
I want to break that down
and kind of understand it a little bit.
(upbeat lively music)
So we've looked at this before
and there was some data from these guys in Belgium,
that were updating a Google sheet, and that worked well.
It was really interesting if you guys recall
when we did that video.
I think I covered it twice.
And I think that was really insightful,
but now I have a lot more data.
Because the thing is that,
with data, you need a whole lot of it
in order to kind of tease out the signal from the noise.
So what that means, is that when you have a small sample
or particularly biased sample of data.
You can get kind of false positives
and results that aren't actually true.
And so, what I'm excited about,
why I'm doing this video again today,
is because I have a lot more data now.
Coming in from a way that's much more reliable.
Let's dig into that in a moment,
but first I want to talk about kind of the concept here.
And before we do that, time to fight dad bod.
(upbeat lively music)
Back here in the office.
Gonna take a look and explain
how batteries actually degrade.
So we can understand what this means in terms of Tesla.
But first, a message from our sponsor.
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So Wunder Capital sponsored the show before
and we have a really good partnership going on
because I love what they do.
I love that they're helping fight climate change
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I'll put a link in the description down below.
Okay, back to the data.
So Tesla uses these lithium ion batteries.
This is an 18650 cell.
This is what you get in the Model S and X,
and then in the Model 3 you have a different one, the 2170.
And the big question is always,
why do they degrade or how does it happen?
And why do Tesla batteries seem to have this magical power
to live longer than all of the other devices
and things that use basically the same technology.
Well, I did some research and basically what happens
is there's two sides to a battery.
There's two parts to it.
And I'm gonna read from a battery tested,
that posted this on Reddit, in a very simple way.
Because I think that's the best way to really think
about these things.
Okay, so he says the batteries have a few main parts.
The anode, negative.
And the cathode, positive.
And the separator between them,
and some stuff in between.
Usually a liquid that conducts ions.
When you charge a battery, you are cramming
a whole bunch of the lithium-ions into the anode.
Kind of like absorbing water into a sponge.
When you use the battery these ions flow to the cathode,
generating electrical current.
That's what power your devices.
Over time by cramming ions in and out of the anode
and cathode you begin to damage the sponge,
so it can't hold as many ions anymore.
Now there was another study I found
on Popular Mechanics about this,
that talked about it in a little bit more detail.
And they basically said a high end lithium palmer battery
can lose up to 20% of its capacity
after a thousand charge cycles.
Another way to think of this,
is to imagine that every time you
recharge your laptop or your Tesla in this case.
You shave a few seconds off its maximum battery life.
Erratic charging and heat can speed up the degradation.
Batteries degrade even if you don't use them.
According to battery testing from Cadex Electornics,
a fully charged lithium-ion battery
will lose about 20% of its capacity
after a year of typical storage.
Increase the temperature to just over
100 degrees Fahrenheit, and in a hot attic for example,
and the number is up to 35%.
On the other hand, an empty battery pack
can eventually fall into deep discharge.
At which point the batteries protection
to prevent the power from reaching
the defective battery cells is triggered.
This leaves the battery unable to charge.
So that's the typical scenario
in which the batteries just kind of lost their charge
and this is what you see.
But Tesla batteries seem to defy these physics here.
And not being somebody that's a battery technician.
I'm not gonna go into how this works and all of that.
I do think that it's really interesting
but I also believe that I'm fully not qualified
to talk about that.
I'm gonna come at it from the data, science approach.
Which, is what I have been employing in business
for almost 20 years now.
And that is to look at the results.
Look at what the data is trying to tell us.
We now have data from Teslab to look at this
in a more objective way.
What Teslab does is they are kind of like
Fitbit for your Tesla.
And there are thousands of Tesla owners
that have it installed.
Every time they drive it logs their trip.
Every time they charge it logs the charging,
because it gives you data like your phantom drain
and your efficiency rating and those kind of things.
And using that database I've been able to
basically come up with a new study on battery degradation.
With that, what we're gonna do is see what the data shows.
And lets put aside the physics of how it may
or may not work for now.
So in this study we have over 2600 vehicles
that we looked at.
And almost 200,000 distinct times that they've
charged their vehicles with over 500,000 trips.
500,000 times they've actually driven.
With these max end odometer,
or the one with the most distance on it at 228,000 miles.
And the distribution of the percent battery remaining,
meaning how much charge is left
compared to the original charge.
We can see that almost all of them are
really high in the 90s, if not close to 100%.
And this data does include cars
that were all the way back to 2012.
Up to ones that are very new in 2018.
And you can see that at 100% we have 33.59,
23% of them are at 99%.
And if you were to take basically everything
from 95 and above, your looking at 91% of the cars.
So we're looking at a sizeable amount of data
and you can see that 91% of them have 95%
or better of their battery remaining.
And if you want to take a little bit deeper look into this,
we can break out each individual car and plot them,
and then see a trend that appears.
And this is really interesting
because we can slice this by a few different factors.
One being charge count.
So looking here each dot is a vehicle,
the Y-axis is how much battery percentage is remaining,
and the X-axis in this case is how many charges
that this car has actually done.
Some of them have an extremely large amount
and other ones have very few.
If you want to look at drive count,
we can do that as well.
You can see that it still is pretty much the same story.
It gets a little bit more spread out.
The average temperature is kind of an interesting one
because you would think that maybe ones
that are in extreme cold or extreme heat
have higher degradation,
but that doesn't really pan out.
You can see that the ones with the higher amount
of degradation kind of run the gamut here.
From the low 40s to the upper 80s.
And on total miles this was as interesting one,
because a lot of them of course are bunched up.
A lot of the cars are pretty new.
But again there's not a clear pattern that emerges.
And in fact a lot of the ones that have
that high amount of degradation
appear in these low mileage.
There may be something going on with these cars individually
that maybe Tesla needs to look at.
But the overall trend, the overwhelming story here
is that these things hold their charge for a long time.
So when it comes to your Tesla I wouldn't worry about this.
Don't forget that you have an eight year,
infinite mile warranty.
Unless you have a Model 3 then it's 100,000 miles.
In any event the battery is gonna outlast your likelihood
of keeping the car.
Now I know some of you will argue
that your gonna keep the car forever
and I applaud you for that.
I'm not one of those people.
But I do think there's a case to be made here
about what Tesla's doing about their batteries
that hopefully other manufacturers of electric vehicles
and maybe even potentially other manufacturers
of electronics could employ to help really just make
these things service better as consumers.
So let me know what you think in the comments down below.
And don't forget, when you free the data,
your mind will follow.
Thanks for watching and I'll see you guys
back here next time.