Readings of the owners forums indicate that complete battery failures on
Teslas are quite rare. They have a good redundancy model of parallel cells
within a module, with 14-16 large modules that are in series to provide
350-400v DC, and thermal regulation.

There are issues, however:

-diagnostics software is unavailable to people outside of Tesla (except
maybe in Massachusetts which has a right to repair law). This software is
needed to perform certain diagnostics and repairs. It is akin to Toyota
Techstream being required to fix certain errors on modern Toyotas.
(Techstream, in contrast, is available to third parties across the world.)
This is a fairly closed ecosystem.

-limited parts availability (a growing pains issue, that in some cases is
made worse by not having multiple distributors or aftermarket parts to
choose from).

-Supercharger access can be remotely disabled after purchase. This is known
to have happened for cars that have been in accidents (however big or
small, whether just cosmetic only or not) where Tesla hasn't been engaged
and paid to reinspect and repair the car.

-firmware cannot be reverted to earlier versions in case of issues or
preferences for earlier feature sets (at least, reversion cannot be done by
regular owners, and isn't something Service Centers can do either.
Supposedly only corporate engineers can do it.)

-door handles on Model S are now at a 3rd revision. Maybe Tesla will find a
solution that reduces electromechanical complexity using what they've
learned with X and 3.

-MCU memory storage wear, possibly due to excessive log writes in early
firmware. Supposed to be reduced in recent firmware.

-MCU bubbles and adhesive dripping issues on earlier model years.

-MCU yellowing on the left and right sides, most noticeable with a white
background, on both S and X, and reported on both MCU1 and MCU2. This is
mostly a cosmetic issue.

-12v battery life may vary. Some reports indicate suboptimal charging
voltages and frequency. Some owners have added battery maintainers. Cars
with 100 kWh packs are reported to have a dedicated 12v feed direct from
the main pack that reduces load on the 12v battery.

-reports of control arm issues on earlier model years (ball joint corrosion
and cracking). Corrosion may be worse in some climates and road treatment
conditions.

-unclear what will happen for owners in cases of greater than average
battery degradation (but not outright failure) (this seems unusual in
general but there is evidence that some '90' packs are losing capacity
faster than normal.) '90' packs have gone through several revisions. The
'90' packs are reported to include silicon in the cell chemistry.

-discrepancies in advertised capacity vs actual capacity. '90' packs store
less than 90 kWh. '100' packs store over 100 kWh. The '100' pack has a lot
more range than the '90'; more than the basic numerical difference would
suggest.

-unclear what will happen for owners who have paid for FSD/full self
driving capability, if it turns out the car sensor hardware cannot support
it, even after upgrading the Autopilot computer to say AP3. (The AP3
computer is currently under development.) The answer may be different for
customers who included the capability with their original order, on the
Monroney label vs those who enabled it post-delivery. The AP2 sensor
hardware on cars sold to customers starting in late 2016 was advertised as
being FSD-ready.



On Mon, Oct 8, 2018, 20:12 George E Swartz via EV <ev@lists.evdl.org> wrote:

> I didn't like the idea of thousands of little cells either, when I first
> looked at the Tesla design.
>
> The key word here is "availability", not MTBF, or reliability. The Tesla
> battery can withstand many single point failures without affecting
> performance or operation of the car, therefore the car remains available
> in spite of failures.  Individual Tesla cells are also fused which reduces
> fire danger. Single point failures in large format batteries cause greater
> percentage degradation per failure.
>
> I had a career in public transportation and availability of rolling stock
> is a very important aspect of any fleet of buses.
>
>
>
>
>
>
>
>
> > Wow, huge misunderstanding of "reliability"..
> >
> > There is a huge difference between the poor reliability of large numbers
> > of
> > single-point failures compared to the HUGE redundancy in the Tesla
> battery
> > with dozens of parallel redundancy at each step of the battery.  I'd take
> > the Tesla design any  day as being far more reliable...
> >
> > Bob
> >
> >
> >  On Monday, October 8, 2018 3:45 PM, Mark Hanson via EV
> > <ev@lists.evdl.org>
> > wrote:
> >
> >  Aside from the high price the main reason I wouldn't buy a Tesla is
> > they're
> > the only manufacturer that has uses 6800 flashlight batteries (2170) in
> an
> > onroad vehicle. I just think of all those points of failure and the
> > complexity of monitoring that reduces reliability.  While Consumer
> Reports
> > gave it high marks for handling etc, they gave it a low score for
> > reliability.  Currently they send a "Tesla Ranger" out to your house for
> a
> > battery field repair as this cost is built into the price of a pricey
> car.
> > I don't know how this business model will work on lower prices $30k
> > versions.  I'm surprised the media doesn't mention the thousands of itty
> > bitty cells in a Tesla and that no one else does it that way for
> > reliability
> > reasons (even with each one fused) Have a renewable energy day Mark in
> > Roanoke Va Www.Reevadiy.org.
> >
> > Sent from my iPhone
> > _______________________________________________
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