
Tesla to Buy Energy Storage Firm Maxwell Tech at $4.75 a Share - joshe
https://www.bloomberg.com/news/articles/2019-02-04/tesla-to-buy-energy-storage-firm-maxwell-tech-at-4-75-shr-value
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zaroth
I miss the full power regenerative braking when using my Tesla in the cold.
Like, I really miss it and don’t like driving the car as much when it just
coasts when I lift the accelerator.

I actively dislike pressing the brake pedal anymore, and feel cheated whenever
I have to touch it except to activate Hold at a stop.

If supercaps could give me full regenerative braking at 0°F then I’d pay an
extra $1-2k for the feature absolutely.

In warm climates I can absolutely see brake pads never being replaced. The
only time I use the brake pads to slow down is in sub-freezing temps and once
in an emergency.

For those who haven’t driven an EV with strong regen braking, you drive with a
single pedal. “Neutral” is the accelerator slightly depressed. Lift your foot
to slow down, fully lifting your foot is a _strong_ braking down to about 10
mph. I should look up how fast you get 60-10 with a warm Tesla on regen alone.
You drive with a single pedal, and you can dart in and out of traffic very
nimbly because over-accelerating for a lane change and then regen’ing back to
cruising speed is very efficient and fun and you don’t have to move your foot
to another pedal. But regen degrades as the battery cools.

A frozen battery will barely regenerate at all, at 0°F it’s actually
disconcerting when you lift your foot and the car just... coasts. The display
does have a gauge showing how much regen is available, so it’s not a surprise
but it literally feels weird.

~~~
Shivetya
To each their own. I like my TM3 and enjoy regenerative braking but there
really is not reason to use a blended braking system which keeps with the
current petrol car model of, use the brake pedal to slow down. It also may be
safer since your foot will be over the brake when needed.

Chevrolet used this on the Volt for normal driving, you press the brake pedal
and it decides how much hydraulic brakes you need over what regeneration can
provide. Audi is going this route too. What makes it even better is they can
totally mask the loss of regeneration in cold weather which can be
disconcerting.

If anything I think Tesla should make it an option, the loss of regen braking
even when the pack is only saturated to 40F is bad enough and just useless
below freezing. They can do wonders with OTA so there is no reason to not
offer all options, low to regeneration, high regeneration, maximum, and
blended.

Again, blended doesn't mean it uses the disc brakes, only that it can when it
has too and this is safer than relying on one pedal driving.

~~~
m_mueller
Your point about safety raises an idea: Why not do the inverse? Your driver
assist tells the car how fast it can drive (GPS, signage), break pedal as well
as a configurable level of assistance tells it how much to stop. Steering is
still mine, and I won't give it up until full autonomous cars with zero driver
responsibility are mass produceable.

~~~
CydeWeys
There's a lot more to how fast you can drive than GPS and signage. There's
also weather, road conditions, if there's parked cars hurting visibility along
the road, whether there's pedestrians near the edge of the road (especially
children who might dart out quickly), etc.

You have to slow down to turn, too. I can't imagine a situation in which you
could let speed be outside the driver's control entirely.

~~~
m_mueller
Yes, therefore you either

a) break yourself on turns, pedestrians waiting, even red light etc.

or

b) choose to let driver assist take over some of these tasks from you

the whole idea is that instead of doing one-pedal driving on the accelerator
it's safer to do one-pedal on the break.

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ChuckMcM
This is a smart move by Tesla, Maxwell's supercap technology is a really good
way to moderate power needs and to extend range.

It also seems like the first step in the "Okay, we have the basic system that
works, lets start knocking off the biggest problems with it." mode that
internal combustion cars have been doing for the last 100 years.

~~~
leggomylibro
I dunno, I could be using them wrong but I have not been impressed with their
(or any) supercapacitors. At the 1000s of Farads, they seem to bleed charge
like crazy, and it gets a lot worse when they need to deal with mechanical
shocks and vibrations, even the "durablue" ones.

Their low voltage also makes them hard to use; you need to balance them, and
their capacitances vary considerably. Most range from -20/+80% to -10/+20%,
but I guess big customers have options to deal with that. Still, if your
battery pack is 300+V, and your supercapacitors can only charge to 3V...that
seems difficult.

I used to be really bullish on them for regenerative braking - I think some
kinds of buses do use them for that - but having tried to use them, I can't
see them being robust enough for consumer, and especially consumer automotive,
requirements in the immediate future.

Also, it's on the order of 10x the cost for similar capacity to lithium
chemistries, and that comes in a package that weighs on the order of 10x as
much as a similar battery.

But hey, I'm just a layman. It sounds like you probably know more.

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stcredzero
Here's my first thought: Put both supercapacitors and batteries in an electric
car. The supercapacitors can help greatly in a couple of ways. When doing a
fast charge, the supercapacitor bank can absorb the energy super fast, much
faster than a bank of batteries could. Then a microcontroller could control
the transfer of that power more gradually over to the battery. (Unfortunately,
super capacitors, when I last read something about it, could only hold their
charge for 4 days or so, so they couldn't replace batteries themselves.)
Perhaps this could be the key to the 5 minute recharge for cars?

Second, supercapacitors could also save some wear and tear on the batteries
during rapid acceleration and regenerative charging.

~~~
Symmetry
For a capacitor to be used in charging that way it would have to have
something like the same capacity as the car's battery. Supercapacitors tend to
have lower specific energy density than batteries do so this would require
reducing the car's range by something like a factor of 5.

A capacitor much smaller than the batteries acting as a buffer for rapid
acceleration and braking might make sense, though.

~~~
stcredzero
_For a capacitor to be used in charging that way it would have to have
something like the same capacity as the car 's battery. Supercapacitors tend
to have lower specific energy density than batteries_

I was under the misapprehension that they had a much larger energy density.
However, my next thought is that not all charging is the same. Only the 1st
60% of a charge is in the constant current part of the charge curve. After
that, the charge rate falls off. Charging the last 10% of a battery's capacity
takes much longer. What if the supercapacitor bank had about 10% of the
capacity of the battery? That would still be a large increase in the size and
weight taken up by energy storage, though. It looks like just putting more
batteries in the car is the economical thing to do.

~~~
Symmetry
In general capacitors have much higher power density but much lower energy
densities than batteries and supercapacitors are somewhere in between.

[http://large.stanford.edu/courses/2012/ph240/aslani1/](http://large.stanford.edu/courses/2012/ph240/aslani1/)

Using a capacitor for the last 10% might make sense, or it might not. It's all
about the specific numbers. It might be that a larger battery charged up to
90% might be better than a slightly smaller battery charged to 100% with the
assistance of a capacitor. If you're adding a capacitor for power reasons
anyways this might be a way to get more use out of it.

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throwaway5752
It's interesting. Maxwell has been around for decades. Publicly they were
known for ultracapacitors (non-expert opinion is that this would be a sweet
spot for regenerative breaking capture in Teslas). But seems like nothing
worth acquiring the company over - there are other vendors and they could just
set up a multi-year supplier contract.

There are some articles/rumors out there about dry electrode battery tech
Maxwell was working on.

~~~
newnewpdro
> There are some articles/rumors out there about dry electrode battery tech
> Maxwell was working on.

If this acquisition included any breakthrough-level battery technology, it'd
be for far more than $218M as it probably would have involved a bidding war
considering the stated electrification plans from all major auto
manufacturers.

~~~
throwaway5752
Why do you think Tesla acquired Maxwell, then? Why did Maxwell sell existing
lines of business several months ago to focus on the dry battery tech and
ultracapacitors?

I don't know enough about dry battery electrode tech to know how much progress
there is, how much an of an improvement they are above existing commercial
technology, or who else has IP in the space.

Your response seems a bit high on the cynicism/information ratio, but I would
be genuinely grateful for more information about this.

~~~
newnewpdro
I persume it's to bolster their battery tech and R&D dept. It just doesn't
seem like anything obviously game-changing from where I'm sitting.

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jmpman
This seems to make more sense for optimizing 0-60mph acceleration metrics than
just about anything else. Using SuperCaps, a base Model 3 could have the 0-60
times of a P100D for much less than the cost of the required batteries.

4WD off road vehicles could also have much higher torque for brief periods of
time.

~~~
jseutter
While true, I think cold temperatures might be the more applicable scenario.
When the batteries are cold, the amount of power you can extract is limited,
as is the amount of power you can inject by regen braking. This is one factor
that leads to crappy range in cold climates.

Capacitors can smooth out the power curve - need 1000 amps of current for 4
seconds? No problem, that comes from the capacitors and the battery only sees
a draw of 200 amps. Need to regen 600 amps for 15 seconds? No problem, dump
that into the capacitors and recharge the batteries at 50 amps for the next
minute.

Knowing Tesla, they will use capacitors to offer both; a super-plaid mode that
can supply 1800 amps momentarily, as well as better cold weather performance.

~~~
jmpman
Can you market the cold temp regen? Maybe? Can you market 0-60 numbers or 4wd
capability? Absolutely. Which one is sexier? I think Elon would say the
performance numbers.

~~~
HeadsUpHigh
There is literally no reason why they have to pick between the 2. It's one
system that can do both depending on the situation. Some countries/areas will
care more about the cold temp regen and some other markets will care more
about 4wd or the 0-60 performance. The great thing about EVs is that you can
just redirect power to whatever you need at any given time.

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nisten
Ok we know that ultra-capacitors carry about 10x less energy/kg than current
li-ion batteries.

This means they have limited use in small consumer cars, other than maybe
helping the brakes or conditioning power. What they lack in weight, they make
up in charge/discharge times.

Being that a truck weighs multiple times more than a sedan, it's batteries are
unlikely to absorb regen braking. So a small capacitor bank makes sense. A
large capacitor bank would be useful if the truck was using overhead charging
cables for a small section of the road. Or if a public transport bus was
quickly charging between every few stations, it could then function all day.

The large weight of the capacitor bank isn't a problem if it's used in a
charging station, where 3-phase 400+ volt power may not be available. This
means that any level 1,2 charger can be upgraded to a level 3 without needing
to dig any trenches, further improving the user experience of the car owner
and reducing range anxiety to a minimum.

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Gravityloss
The cars already have heat pumps in the form of air conditioners. They could
be designed with minor modifications to also be used for heating, improving
the energy efficiency of cold vehicles a lot.

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maxxxxx
Why do journalists always change units? Usually they report a sale by
valuation but with price per share I first have to look up the company and
find the number of outstanding shares.

~~~
alanwong
It's journalists' job to highlight what's noteworthy, and in an acquisition
it's not always the valuation of a company. In this case, the price per share
is headlined to highlight the premium (55%) Tesla is paying for Maxwell Tech's
shares.

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kumarvvr
Can these capacitors be used in any way for faster charging of the car? Like
have a capacitor bank pre-charged and then unload it into a car for much
faster charging.

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sitkack
I hope this doesn't affect the supply of Maxwell supercaps in the overall
market. It really is star trek level technology.

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pdq
Why is this newsworthy, other than Tesla is acquiring a micro cap company in
an all stock offer? There's not even a blog post on Tesla.com or a tweet by
Elon regarding Maxwell.

~~~
smileysteve
Because Maxwell is a fairly popular name in the field; and this is interesting
for hackers...

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carlivar
Certainly more fuel for the fire with Tesla bears, given that Maxwell has been
in trouble with the SEC on multiple occasions for financial shenanigans:

[https://www.sec.gov/news/press-
release/2018-48](https://www.sec.gov/news/press-release/2018-48)

[https://www.sec.gov/news/press/2011/2011-31.htm](https://www.sec.gov/news/press/2011/2011-31.htm)

~~~
martinald
Is Musk pulling this to try and distract attention from the sales estimates in
Jan 19? It's looking like an enormous, enormous plunge.

~~~
sidcool
I don't think so. The China Gigafactory news was enough to silent many of the
shorters and Tesla critics.

