
Tesla batteries will live longer than expected, survey finds - doener
https://www.engadget.com/2018/04/16/tesla-battery-packs-live-longer/
======
rgbrenner
Tesla used to (still does?) put larger batteries in their cars than ordered,
and limits them with software:

[http://www.thedrive.com/sheetmetal/12820/tesla-is-
silently-p...](http://www.thedrive.com/sheetmetal/12820/tesla-is-silently-
putting-bigger-battery-packs-in-its-entry-level-model-s)

So if these numbers are from the owners reading them from the dash... they
wouldn't know their 40kwh battery was actually a 60kwh battery that was
software limited. That's a lot of spare capacity to hide aging.

Remember when they flipped a switch to allow Florida owners to use the range
of their larger batteries to escape the hurricane:

[https://techcrunch.com/2017/09/09/tesla-flips-a-switch-to-
in...](https://techcrunch.com/2017/09/09/tesla-flips-a-switch-to-increase-the-
range-of-some-cars-in-florida-to-help-people-evacuate/)

Larger batteries than purchased are clearly quite widespread with Tesla.

~~~
michaelt
Not saying it's impossible - or even unlikely - but has anyone actually done a
tear-down confirming there are identical batteries in cars sold as having
different batteries?

The reason I ask is a lot of lithium cell suppliers say "This is an x kWh
battery... but don't charge above 90% or discharge below 20%" so the usable
capacity is 70% of the advertised capacity. Could be that Tesla just
advertises the usable capacity.

~~~
mattbessey
Hmm, I think it's not relevant because those constraints apply on the cell
level, and Tesla battery packs are just thousands of small cells.

Well I suppose it depends if you leave x% of cells unused (prolonging their
life, and ready to swap in when other cells lose capacity, much like SSDs do)
or distribute across all cells, lowering the charging level X%. Either way I
suspect you're hitting the "full cycle" that diminishes the cells life, so
probably better to use the former strategy, leaving you with some healthy
cells in the future.

Curious to hear if someone suspects otherwise though.

~~~
pjc50
They don't have cell-level control, so it's definitely the latter. The cells
are wired in strings, then paralleled.

[http://qnovo.blogspot.co.uk/2014/11/31.html](http://qnovo.blogspot.co.uk/2014/11/31.html)

(although apparently they do have individual fuses!)

------
taneq
For some lithium battery chemistries (eg. LiIon) they have a limited shelf
life regardless of number of cycles (which is why, for example, phones and
tablets tend to drop sharply in battery life after 2-3 years regardless of
level of usage). I'd be curious to know how the Tesla packs perform in that
regard.

~~~
askvictor
LiIon refers to a whole range of different chemistries; Tesla uses Lithium
Nickel Cobalt Aluminum Oxide which offers a longer lifespan while typically
laptops and phones use Lithium Cobalt Oxide.

I was also under the impression that Lithium batteries suffer from calendar
degradation, but I wonder how much of a thing that is with modern batteries if
they have good thermal management (like Teslas do), or if we even notice it
when actually using a device (laptops and phones run the battery hard and hot,
so end up having a 2-3 year lifespan from normal use.

~~~
makomk
Tesla use Panasonic's NCR18650B cells which were originally designed for
laptops. (At least in the Model S anyway, I think the Model 3 is using
something a little more custom.)

~~~
askvictor
You are describing battery sizes, not chemistries. 18650 is a standard cell
size which Tesla uses in their older vehicles, and is common in older laptops
and powertools. The types of chemistry used in it may vary (just like you can
get AA cells in alkaline, NiCd, NiMH, and other chemistries)

~~~
makomk
No I'm not. 18650 is the size, NCR1850B is a very specific model of off-the-
shelf cell in that size manufactured by Panasonic with a specific chemistry
and specification. As far as I can tell (it's not something the manufacturers
release much information about publicly) the "NCR" part identifies the
chemistry as Lithium Nickel Cobalt Aluminum Oxide.

------
skunkworker
Well the data shows just how much active cooling helps to lengthen their live.
Gen 1 Leaf packs didn't have active cooling and their life goes downhill
quickly.

[https://insideevs.com/nissan-issues-statement-on-
leaf-30-kwh...](https://insideevs.com/nissan-issues-statement-on-leaf-30-kwh-
battery-degradation/)

~~~
thephilsproject
No Leaf has active cooling, including the latest 40kWh Gen4.

~~~
ItsMe000001
I'm not trying to nitpick, I really cannot tell and don't have context or pre-
existing knowledge to resolve it for myself and I'm not a native speaker
either:

Do you mean "No Leaf has active cooling", or do you mean "No, Leaf has active
cooling" (with a comma)?

Because I _suspect_ the comma version, because I think the no-comma version
would probably have been formulated slightly differently?

~~~
PuffinBlue
The reply you're responding to was a rebuff of the original parent to the
thread - so it should be read without a comma i.e. it is correctly written.

You could write it as:

"Not a single Leaf has active cooling" or "None of the Nissan Leaf's have
active cooling".

The above two alternative sentences aren't as elegant or concise as the
original, hence why it was likely chosen.

------
nottorp
Netherlands - Belgium. Temperatures there seem to get close to freezing, but
mostly not below. At least it's not California, so the batteries do hold well.

Is there a survey from places with actual winters anywhere?

~~~
sunstone
I believe there's been a fleet of Model S taxis in Montreal Canada for several
years. They could have some cold weather data. Oh, and of course Tesla sells a
ton of cars in Norway which can get chilly too.

------
sschueller
Is this survey more than just reading the stats of the dashboard? How do we
know those are correct? How much reserve do the Tesla battery packs have that
is not reported in the car dashboard?

~~~
greglindahl
If Tesla has a reserve, the most obvious implementation would have a curve of
degradation that would give it away: 100% for a long time, then a significant
and steady drop.

Hard disks and SSDs work that way; hard disks have a 20% reserve these days.

------
kumarski
1.2 Billion kilograms of lithium are estimated in reserves on planet earth -
estimated by the USGS.

10 Kilograms of lithium are needed for each Tesla battery

~122M Tesla batteries can be made.

0.5M teslas produced per a year by 2020 is their aim.

20 to 100 gigafactories would mean 50 to 300 years of lithium availability.

8 year durations on Tesla batteries.

I'm not sure extended duration on these things means anything environmentally
relevant.

~~~
llukas
I think your data is bit off:

[https://minerals.usgs.gov/minerals/pubs/commodity/lithium/mc...](https://minerals.usgs.gov/minerals/pubs/commodity/lithium/mcs-2018-lithi.pdf)

53M tons of lithium available = 53000M of kg = 5300M of Tesla batteries can be
made...

~~~
elihu
Also, that's just the lithium deposits we know about now.

~~~
greglindahl
Actually, no, that's the lithium deposits that we know can be extracted at the
current price. If the price goes up, the reserves rise immediately, because
more of what we know becomes extractable.

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josefresco
...yet, my last two laptop batteries stopped holding a charge for more than 30
min after one year (I'm only slightly exaggerating)

