Re: [EVDL] Tesla cell size

2017-04-14 Thread Cor van de Water via EV 
Hi David, others.
I think the "packing" argument is ignoring one big issue that totally flips the 
equation around, in addition to a few other considerations.

Look at popular prismatic cells: there are space-efficient pouches inside, but 
the walls of the cells have to be tough and thick
to contain the swelling and pressure that the pouches can exert when charging.
Even in modern modules that use pouches like Leaf batteries, there still is an 
aluminum frame around the pouch cells to contain them and on top of that, they 
need large and heavy end-plates to clamp down those modules to prevent the 
pouches from swelling and damaging the cells.

In cylindrical batteries, not only is the container the minimal surface shape 
to contain the cell (for a certain length) but also a thin metal container is 
all that is needed to contain the pressure in the cell, since it has the right 
shape to bear the forces in itself.
So, the minimal amount of material is needed and it is packed pretty 
efficiently.
I am sure someone can do the math and figure out at which wall thickness and 
cylinder diameter the cross-over point is that cylindrical is actually *more* 
space efficient than prismatic.
Note that empty space between cells is not "lost" if it is used for cooling the 
cells, just like prismatic or pouch packs require additional infrastructure for 
cooling - or take a gamble without cooling as in the Leaf.

Cor van de Water
Chief Scientist
Proxim Wireless Corporation http://www.proxim.com
Email: cwa...@proxim.comPrivate: http://www.cvandewater.info
Skype: cor_van_de_water XoIP: +31877841130
Tel: +1 408 383 7626Tel: +91 (040)23117400 x203



-Original Message-
From: EV on behalf of EVDL Administrator via EV
Sent: Fri 4/14/2017 9:50 AM
To: Electric Vehicle Discussion List
Subject: Re: [EVDL] Tesla cell size
 
On 13 Apr 2017 at 22:04, Michael Ross via EV wrote:

> A cylinder only has to be oriented for polarity, it
> can have any radial orientation.

We had a rather similar discussion here many years ago (20?) about Optima 
lead batteries, which used (and still use) cylindrical cells.  

This thread has named some of the advantages of cylindrical cells.  Those 
aren't insignificant by any means.  However, a cylinder isn't as efficient 
as a rectangle if your goal is to package the most active material per unit 
of available vehicle space.

The exception to this would be a case where the form factor matches the 
container perfectly, such as filling the round frame tubes of an e-bike with 
cells.

David Roden - Akron, Ohio, USA
EVDL Administrator

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Re: [EVDL] Tesla cell size

2017-04-14 Thread EVDL Administrator via EV 
On 13 Apr 2017 at 22:04, Michael Ross via EV wrote:

> A cylinder only has to be oriented for polarity, it
> can have any radial orientation.

We had a rather similar discussion here many years ago (20?) about Optima 
lead batteries, which used (and still use) cylindrical cells.  

This thread has named some of the advantages of cylindrical cells.  Those 
aren't insignificant by any means.  However, a cylinder isn't as efficient 
as a rectangle if your goal is to package the most active material per unit 
of available vehicle space.

The exception to this would be a case where the form factor matches the 
container perfectly, such as filling the round frame tubes of an e-bike with 
cells.

David Roden - Akron, Ohio, USA
EVDL Administrator

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EVDL Information: http://www.evdl.org/help/
= = = = = = = = = = = = = = = = = = = = = = = = = = = = = 
Note: mail sent to "evpost" and "etpost" addresses will not 
reach me.  To send a private message, please obtain my 
email address from the webpage http://www.evdl.org/help/ .
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Re: [EVDL] Tesla cell size

2017-04-14 Thread Hoegberg via EV 
Från: EV <ev-boun...@lists.evdl.org> för Michael Ross via EV <ev@lists.evdl.org>
Skickat: den 14 april 2017 04:04
Till: Electric Vehicle Discussion List; Mark Hanson
Ämne: Re: [EVDL] Tesla cell size 


> Regarding fuses, if you check out some images of pack teardowns you can see
the fuses are really just a fusible link welded to each cell, connecting it
to the "backplane." They have simply sized the connecting wire to melt
under a damaging short condition. Foolproof, they fail open, and cheap.


I think that also pouch cells can have "fuses", 
sometimes I have seen punched holes in the Foil/tabs close to the cell, I think 
that is "fusing", less area just below where they will be welded in parallel at 
the end of the tabs 

/ John
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Re: [EVDL] Tesla cell size

2017-04-14 Thread Michael Ross via EV 
The larger cell allow​s more cooling surface. I think Tesla has optimized
for power density choosing the slightly larger size. Also optimized for
manufacturing efficiency. A cylinder only has to be oriented for polarity,
it can have any radial orientation.

Regarding fuses, if you check out some images of pack teardowns you can see
the fuses are really just a fusible link welded to each cell, connecting it
to the "backplane." They have simply sized the connecting wire to melt
under a damaging short condition. Foolproof, they fail open, and cheap.
They have to connect each cell anyway, and it isn't like they push the
cells between two springs, a la flashlights. They are going to weld the
connections anyway.

On Apr 13, 2017 9:08 AM, "Mark Hanson via EV"  wrote:

>
>
> >
> > Thanks Mike
> > It looks like their 18650 cells have only grown slightly.  Guess you
> can't argue with success. I remember when they were starting in California
> and I told a Tesla salesman that that's 6800 points of failure and he said
> that's 6800 points of redundancy.  I've always had it beat into my pointy
> engineering head to minimize component count but with embedded fuses in
> each cell that's probably a good recipe although no other manufacturers are
> doing it.
> > Best regards
> > Mark
> >
> > Sent from my iPhone
> >
> >> On Apr 12, 2017, at 3:26 PM, Michael Nickerson <
> mikenickers...@gmail.com> wrote:
> >>
> >> It looks like it.  In the link below they describe them as "2170 cells"
> but I think they are a similar format.
> >>
> >> https://www.tesla.com/blog/battery-cell-production-begins-gigafactory
> >>
> >> I agree that Tesla is the only auto manufacturer using the cylindrical
> cells, but they are used by the millions in laptops, so the technology is
> well established.
> >>
> >> It seems to be working for them.  I haven't heard of any reliability
> problems related to the cells or their interconnects.
> >>
> >>> On Apr 12, 2017 6:45 AM, "Mark Hanson via EV" 
> wrote:
> >>> Is tesla still using 6800 or so of 18650 itty bitty cells in their on
> road vehicles like the S and model 3?  Do they use these small cells in
> their Tesla Wall home UPS packs as well?  I wonder if they'll continue
> these small cells at their giga factory in Reno since *no* other
> manufacturer is doing so.
> >>> Best regards
> >>> Mark
> >>>
> >>> Sent from my iPhone
> >>>
> >>> > On Apr 10, 2017, at 4:04 PM, via EV  wrote:
> >>> >
> >>> > Send EV mailing list submissions to
> >>> >ev@lists.evdl.org
> >>> >
> >>> > To subscribe or unsubscribe via the World Wide Web, visit
> >>> >http://lists.evdl.org/listinfo.cgi/ev-evdl.org
> >>> > or, via email, send a message with subject or body 'help' to
> >>> >ev-requ...@lists.evdl.org
> >>> >
> >>> > You can reach the person managing the list at
> >>> >ev-ow...@lists.evdl.org
> >>> >
> >>> > When replying, please edit your Subject line so it is more specific
> >>> > than "Re: Contents of EV digest..."
> >>> >
> >>> >
> >>> > Also, please be careful not to append the entire digest to your
> reply. Many mail systems do this by default. Trim or delete the digest text
> from the bottom of your message, and quote only the parts to which you're
> replying.
> >>> >
> >>> >
> >>> >
> >>> > Today's Topics:
> >>> >
> >>> >   1. Re: EVWest Tesla Module Prices? (tomw via EV)
> >>> >
> >>> >
> >>> > 
> --
> >>> >
> >>> > Message: 1
> >>> > Date: Mon, 10 Apr 2017 09:54:12 -0700 (PDT)
> >>> > From: tomw via EV 
> >>> > To: ev@lists.evdl.org
> >>> > Subject: Re: [EVDL] EVWest Tesla Module Prices?
> >>> > Message-ID: <1491843252861-4686360.p...@n4.nabble.com>
> >>> > Content-Type: text/plain; charset=us-ascii
> >>> >
> >>> > Iirc in the 85kWh pack there are 16 modules, each module has 6 series
> >>> > connected groups of 74 cells in parallel, so full charge of one
> module is
> >>> > 6*4.2V = 25.2V, and capacity is about 240Ah.  Most modules seem to
> go for
> >>> > around $1200 when sold by individuals, and they usually tell you the
> year
> >>> > and mileage of the vehicle they were taken from.  Might be more cost
> >>> > effective to buy a wrecked Tesla S with low miles since there seem
> to be
> >>> > ample buyers for the drive train, the value of the glass, and scrape
> value
> >>> > of the aluminum body should be considerable, and you could sell the
> modules
> >>> > you don't use.
> >>> >
> >>> > There are two difficulties with Tesla modules imo:
> >>> >
> >>> > 1) The larger the unit size the more difficult packing different
> battery box
> >>> > volumes becomes.  These are quite large, module length with cooling
> tubes is
> >>> > 26.75", width is 11.8", generally resulting in inefficient use of
> volume.
> >>> >
> >>> > 2) The larger the voltage unit, the less flexibility in pack voltage
> due to
> >>> > limits of controller/motor max/min input

Re: [EVDL] Tesla cell size

2017-04-13 Thread Mark Hanson via EV 


> 
> Thanks Mike
> It looks like their 18650 cells have only grown slightly.  Guess you can't 
> argue with success. I remember when they were starting in California and I 
> told a Tesla salesman that that's 6800 points of failure and he said that's 
> 6800 points of redundancy.  I've always had it beat into my pointy 
> engineering head to minimize component count but with embedded fuses in each 
> cell that's probably a good recipe although no other manufacturers are doing 
> it.  
> Best regards 
> Mark
> 
> Sent from my iPhone
> 
>> On Apr 12, 2017, at 3:26 PM, Michael Nickerson  
>> wrote:
>> 
>> It looks like it.  In the link below they describe them as "2170 cells" but 
>> I think they are a similar format.
>> 
>> https://www.tesla.com/blog/battery-cell-production-begins-gigafactory
>> 
>> I agree that Tesla is the only auto manufacturer using the cylindrical 
>> cells, but they are used by the millions in laptops, so the technology is 
>> well established.
>> 
>> It seems to be working for them.  I haven't heard of any reliability 
>> problems related to the cells or their interconnects.
>> 
>>> On Apr 12, 2017 6:45 AM, "Mark Hanson via EV"  wrote:
>>> Is tesla still using 6800 or so of 18650 itty bitty cells in their on road 
>>> vehicles like the S and model 3?  Do they use these small cells in their 
>>> Tesla Wall home UPS packs as well?  I wonder if they'll continue these 
>>> small cells at their giga factory in Reno since *no* other manufacturer is 
>>> doing so.
>>> Best regards
>>> Mark
>>> 
>>> Sent from my iPhone
>>> 
>>> > On Apr 10, 2017, at 4:04 PM, via EV  wrote:
>>> >
>>> > Send EV mailing list submissions to
>>> >ev@lists.evdl.org
>>> >
>>> > To subscribe or unsubscribe via the World Wide Web, visit
>>> >http://lists.evdl.org/listinfo.cgi/ev-evdl.org
>>> > or, via email, send a message with subject or body 'help' to
>>> >ev-requ...@lists.evdl.org
>>> >
>>> > You can reach the person managing the list at
>>> >ev-ow...@lists.evdl.org
>>> >
>>> > When replying, please edit your Subject line so it is more specific
>>> > than "Re: Contents of EV digest..."
>>> >
>>> >
>>> > Also, please be careful not to append the entire digest to your reply. 
>>> > Many mail systems do this by default. Trim or delete the digest text from 
>>> > the bottom of your message, and quote only the parts to which you're 
>>> > replying.
>>> >
>>> >
>>> >
>>> > Today's Topics:
>>> >
>>> >   1. Re: EVWest Tesla Module Prices? (tomw via EV)
>>> >
>>> >
>>> > --
>>> >
>>> > Message: 1
>>> > Date: Mon, 10 Apr 2017 09:54:12 -0700 (PDT)
>>> > From: tomw via EV 
>>> > To: ev@lists.evdl.org
>>> > Subject: Re: [EVDL] EVWest Tesla Module Prices?
>>> > Message-ID: <1491843252861-4686360.p...@n4.nabble.com>
>>> > Content-Type: text/plain; charset=us-ascii
>>> >
>>> > Iirc in the 85kWh pack there are 16 modules, each module has 6 series
>>> > connected groups of 74 cells in parallel, so full charge of one module is
>>> > 6*4.2V = 25.2V, and capacity is about 240Ah.  Most modules seem to go for
>>> > around $1200 when sold by individuals, and they usually tell you the year
>>> > and mileage of the vehicle they were taken from.  Might be more cost
>>> > effective to buy a wrecked Tesla S with low miles since there seem to be
>>> > ample buyers for the drive train, the value of the glass, and scrape value
>>> > of the aluminum body should be considerable, and you could sell the 
>>> > modules
>>> > you don't use.
>>> >
>>> > There are two difficulties with Tesla modules imo:
>>> >
>>> > 1) The larger the unit size the more difficult packing different battery 
>>> > box
>>> > volumes becomes.  These are quite large, module length with cooling tubes 
>>> > is
>>> > 26.75", width is 11.8", generally resulting in inefficient use of volume.
>>> >
>>> > 2) The larger the voltage unit, the less flexibility in pack voltage due 
>>> > to
>>> > limits of controller/motor max/min input voltage.  Voltage of these is 
>>> > quite
>>> > large, 25.2V full charge. So for example 7 modules in series
>>> > exceeds max voltage for the Curtis 144V AC controller with max 170V input
>>> > since at full charge they would be 176.4V, although if you give 20 min or 
>>> > so
>>> > after full charge for the cells to "relax" in voltage before closing the
>>> > contactor to the controller it shouldn't be an issue, and much of the time
>>> > you could just do a partial charge. Six modules do not make full use of 
>>> > the
>>> > voltage range of the controller, limiting peak power.  Higher voltage 
>>> > motors
>>> > that require > 300V have a different problem in that they require many of
>>> > these modules in series, making it difficult to fit enough modules in a
>>> > converted vehicle to supply the required voltage.
>>> >
>>> > --
>>> > View this message in context: 
>>> >

Re: [EVDL] Tesla cell size

2017-04-12 Thread Michael Ross via EV 
Like ion cells change volume a significant amount as they charge and
discharge. The cylindrical format is really structurally better in this
respect- each cell can handle the stress and the pack doesn't have to be
designed to take it. Compare to pouch cells which end up in a press to keep
volumetric changes controlled. Also automation in manufacturing is better
with cylindrical​s. A pack of cylinders has built-in cooling channels
between the cells. And what Mike N said.

On Apr 12, 2017 3:33 PM, "- - via EV"  wrote:

> See the following for details:
>
> https://www.tesla.com/blog/battery-cell-production-begins-gigafactory
>
> I agree that Tesla is the only auto manufacturer using the cylindrical
> cells, but they are used by the millions in laptops, so the technology is
> well established.
>
> Using the cylindrical cells seems to be working for them.  They can
> support power levels most other production EVs don't reach.  I haven't
> heard of any reliability problems related to the cells or their
> interconnects.
>
> Mike
>
> > On April 12, 2017 at 9:06 AM Paul Wujek via EV 
> wrote:
> >
> > On 2017-04-12 08:45 AM, Mark Hanson via EV wrote:
> >
> > > Is tesla still using 6800 or so of 18650 itty bitty cells in their on
> road vehicles like the S and model 3? Do they use these small cells in
> their Tesla Wall home UPS packs as well? I wonder if they'll continue these
> small cells at their giga factory in Reno since*no* other manufacturer is
> doing so.
> > > Best regards
> > > Mark
> > > Actually Mark, 18650s are so last-year, they are using 2170 cells now
> > > for all of their products, and yes they will continue to use them for
> > > years to come.
> > > -- next part --
> > > An HTML attachment was scrubbed...
> > > URL:  attachments/20170412/e411b64d/attachment.htm>
> > >
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> > > Please discuss EV drag racing at NEDRA (http://groups.yahoo.com/
> group/NEDRA)
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Re: [EVDL] Tesla cell size

2017-04-12 Thread Bill Woodcock via EV 

> On Apr 13, 2017, at 3:32 AM, - - via EV  wrote:
> I haven't heard of any reliability problems related to the cells or their 
> interconnects.

On the first few units, assembled by hand in Asia, they had a lot of problems, 
which was what drove the development of the robotic spot-welding assembly line 
in California.  Being able to do the lots-and-lots-of-cylindrical-cells thing 
hinges entirely on the repeatability of reliable welds that they get from the 
robotic welder.

-Bill




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Re: [EVDL] Tesla cell size

2017-04-12 Thread - - via EV 
See the following for details:

https://www.tesla.com/blog/battery-cell-production-begins-gigafactory

I agree that Tesla is the only auto manufacturer using the cylindrical cells, 
but they are used by the millions in laptops, so the technology is well 
established.

Using the cylindrical cells seems to be working for them.  They can support 
power levels most other production EVs don't reach.  I haven't heard of any 
reliability problems related to the cells or their interconnects.

Mike

> On April 12, 2017 at 9:06 AM Paul Wujek via EV  wrote:
> 
> On 2017-04-12 08:45 AM, Mark Hanson via EV wrote:
> 
> > Is tesla still using 6800 or so of 18650 itty bitty cells in their on road 
> > vehicles like the S and model 3? Do they use these small cells in their 
> > Tesla Wall home UPS packs as well? I wonder if they'll continue these small 
> > cells at their giga factory in Reno since*no* other manufacturer is doing 
> > so.
> > Best regards
> > Mark
> > Actually Mark, 18650s are so last-year, they are using 2170 cells now
> > for all of their products, and yes they will continue to use them for
> > years to come.
> > -- next part --
> > An HTML attachment was scrubbed...
> > URL: 
> > 
> > 
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Re: [EVDL] Tesla cell size

2017-04-12 Thread Paul Wujek via EV 



On 2017-04-12 08:45 AM, Mark Hanson via EV wrote:

Is tesla still using 6800 or so of 18650 itty bitty cells in their on road 
vehicles like the S and model 3?  Do they use these small cells in their Tesla 
Wall home UPS packs as well?  I wonder if they'll continue these small cells at 
their giga factory in Reno since*no*  other manufacturer is doing so.
Best regards
Mark
Actually Mark, 18650s are so last-year, they are using 2170 cells now 
for all of their products, and yes they will continue to use them for 
years to come.

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[EVDL] Tesla cell size

2017-04-12 Thread Mark Hanson via EV 
Is tesla still using 6800 or so of 18650 itty bitty cells in their on road 
vehicles like the S and model 3?  Do they use these small cells in their Tesla 
Wall home UPS packs as well?  I wonder if they'll continue these small cells at 
their giga factory in Reno since *no* other manufacturer is doing so.  
Best regards
Mark

Sent from my iPhone

> On Apr 10, 2017, at 4:04 PM, via EV  wrote:
> 
> Send EV mailing list submissions to
>ev@lists.evdl.org
> 
> To subscribe or unsubscribe via the World Wide Web, visit
>http://lists.evdl.org/listinfo.cgi/ev-evdl.org
> or, via email, send a message with subject or body 'help' to
>ev-requ...@lists.evdl.org
> 
> You can reach the person managing the list at
>ev-ow...@lists.evdl.org
> 
> When replying, please edit your Subject line so it is more specific
> than "Re: Contents of EV digest..."
> 
> 
> Also, please be careful not to append the entire digest to your reply. Many 
> mail systems do this by default. Trim or delete the digest text from the 
> bottom of your message, and quote only the parts to which you're replying.
> 
> 
> 
> Today's Topics:
> 
>   1. Re: EVWest Tesla Module Prices? (tomw via EV)
> 
> 
> --
> 
> Message: 1
> Date: Mon, 10 Apr 2017 09:54:12 -0700 (PDT)
> From: tomw via EV 
> To: ev@lists.evdl.org
> Subject: Re: [EVDL] EVWest Tesla Module Prices?
> Message-ID: <1491843252861-4686360.p...@n4.nabble.com>
> Content-Type: text/plain; charset=us-ascii
> 
> Iirc in the 85kWh pack there are 16 modules, each module has 6 series
> connected groups of 74 cells in parallel, so full charge of one module is 
> 6*4.2V = 25.2V, and capacity is about 240Ah.  Most modules seem to go for
> around $1200 when sold by individuals, and they usually tell you the year
> and mileage of the vehicle they were taken from.  Might be more cost
> effective to buy a wrecked Tesla S with low miles since there seem to be
> ample buyers for the drive train, the value of the glass, and scrape value
> of the aluminum body should be considerable, and you could sell the modules
> you don't use.
> 
> There are two difficulties with Tesla modules imo:
> 
> 1) The larger the unit size the more difficult packing different battery box
> volumes becomes.  These are quite large, module length with cooling tubes is
> 26.75", width is 11.8", generally resulting in inefficient use of volume.  
> 
> 2) The larger the voltage unit, the less flexibility in pack voltage due to
> limits of controller/motor max/min input voltage.  Voltage of these is quite
> large, 25.2V full charge. So for example 7 modules in series 
> exceeds max voltage for the Curtis 144V AC controller with max 170V input
> since at full charge they would be 176.4V, although if you give 20 min or so
> after full charge for the cells to "relax" in voltage before closing the
> contactor to the controller it shouldn't be an issue, and much of the time
> you could just do a partial charge. Six modules do not make full use of the
> voltage range of the controller, limiting peak power.  Higher voltage motors
> that require > 300V have a different problem in that they require many of
> these modules in series, making it difficult to fit enough modules in a
> converted vehicle to supply the required voltage.
> 
> --
> View this message in context: 
> http://electric-vehicle-discussion-list.413529.n4.nabble.com/EVWest-Tesla-Module-Prices-tp4686358p4686360.html
> Sent from the Electric Vehicle Discussion List mailing list archive at 
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> End of EV Digest, Vol 54, Issue 11
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