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Old 10-27-2017, 01:07 AM
  #31  
928 GT R
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gnochi,

This is a fascinating series of posts. I have learned a great deal from your explanations sooooo... Thank you.

Having driven the Tesla P100S, BMW i3 and a few others, I can see that the electric car is going to take significant market share from ICE cars, and quickly!

Porsches history with electric/hybrid vehicles runs back to 1899 with the Lohner-Porsche, (Mixte & Semper Vivus) vehicles of which 65 were sold.

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More recently, Porsche has had incredible success with the 919 Hybrid winning LeMans the last three years.

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Regarding the Mission E, I would love to see Porsche use/develop battery technology that is superior to the Tesla's relatively heavy 18650 liquid electrolyte batteries.

I'm continually looking for solid polymer/film batteries as the "next level" battery technology. The question is when they will be available as mass produced products?

Do you know anything regarding the materials used in the polymer electrolyte or about any companies that produce them?

Regards!
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Old 10-27-2017, 05:32 PM
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Hi 928 GT R,

I'm glad you enjoyed the posts! Agreed, Porsche is in a pretty good position in terms of their technology.

NMC and NCA-based chemistries are pretty heavy for the amount of energy, but they're actually the most energy dense cells available on the market right now. Also, the fact that cylindrical cells are inherently self-supporting means that you can pull some weight out of the module structure. But yes, weight reduction is one of the big goals right now (size reduction is of similar importance).

Solid state or polymer electrolytes... honestly, I don't see them being on the market for at minimum another decade. Lots of small labs, none of which I can name offhand, have gotten tiny button cells to work - topping out at around 300mAh, or an order of magnitude lower than a typical 18650 - at great expense, but there haven't been any results that I'm aware of that are either that impressive or scalable to mass production, a process that itself takes a few years.

The difficulty with the polymer electrolytes is that they don't stay wetted to the anode and cathode, so the resistance goes up massively as the cell is charged and discharged. I'm sure lots of very dedicated and talented people are working on that problem, but it's a fundamental difference between liquids and solids that liquids tolerate significant and random micron-scale size changes at interfaces and solids, well, don't.

The reason that a polymer electrolyte would increase energy density is nothing to do with making the anode or cathode - the current optimization targets, doing things like adding silicon to the graphite anode to increase energy ~5% at the cost of ~25% cycle life - any better. Instead, it increases the voltage limit of the cell.

Every mAh capacity you add at a higher voltage adds more energy than you add at a lower voltage - the incremental energy increase equals the incremental capacity increase multiplied by the current cell voltage. This is why LFP and LTO cells have a fraction of the energy density of LCO, NMC, NCA, etc. - the cells themselves are ~1V lower, so every incremental bit of capacity adds less energy, and the capacity for a given cell is about the same.

Going back to electrolytes, we haven't really changed much in a good 10-15 years. It's not that we haven't been looking, it's that we haven't been able to make anything better. Unfortunately, the electrolyte in question starts to decompose at around 4.5V (permanent cell damage) and starts to cause worse issues (venting, runaway, and if really unlucky, detonation) at around 5V. Depending on the solid state electrolyte in question, though, you might be able to push to around 6V, which might double the energy limit of the cell (don't quote me on that).

All that said, the current state of solid state cells isn't pure uselessness. They are very energy dense. The difficulty, due to the extremely high resistance (orders of magnitude higher than liquid electrolyte) means that your cooling system demands go way up, and the amount of power it is electrically possible to pull goes way down - think 1/10C discharge at best. For trickle power devices - smoke alarms, weather buoys, satellites, and the like - we may be closer to 2-3 years from usefulness. For EVs, we need a bit more power than that (ideally peak around 8C discharge) - the power to energy balance is actually pretty good. The big thing needing improvement right now is fast charge.

Now, that's absolutely something we're working on. The difficulty is using a substance into which lithium ions can readily intercalate at both the anode and the cathode. The LTO cell does a really good job at this - it's not unreasonable to expect 25C continuous charge and discharge for 3000+ cycles, but the current (and likely future) state of EVs can't accept a 50% drop in volumetric energy density and a 70% drop in gravimetric. If, however, an electrolyte capable of 6V (and ensuring the anode and cathode also remained stable at that) were developed that could double the energy density...
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Old 10-28-2017, 12:49 AM
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gnocchi,

I was aware of the energy density advantage of polymer electrolytes but unaware of the interface issues with wetting deterioration above 4 volts between the anode and cathode. Your description makes intuitive sense.

The problem I see with LCO, NMC and NCA being used universally in EV's, is the lack of worldwide cobalt supply for the batteries themselves. Since cobalt is mostly produced as a by-product of copper mining, the supply is limited and it takes significant time and capital to bring large scale mines on-line.

Doubling the risk inherent with the shortage of cobalt is the fact that most of the world reserves are in the Democratic Republic of Congo (DRC). The DRC is the second most unstable jurisdiction on the planet and reliable supply is threatened by governmental and labor instability.

That said, Tesla/Panasonic has reportedly been able to reduce cobalt content to 6% in it's 18650 batteries from nearly 30% in the past.

Tesla's gigafactory is the worlds largest supplier of batteries and the new battery they are manufacturing now is called 2170 (21mm x 70mm) and while I do not know the cobalt content, they claim that it is 10-15 more energy dense but will continue to charge at 4.2 volts (same as the 18650) with less than 1% degradation per year. Pretty impressive!

At what percentage of cobalt content does a liquid electrode battery loose its energy density and how does cobalt content effect charging speed?

Thank you again for helping a rank amateur understand this fascinating new world!
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Old 10-28-2017, 06:07 PM
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Gnochi,
I've read this entire thread and I believe I really understand about 50% of the information conveyed. I have a 2018 Panamera 4 E Hybrid sitting at the San Diego Port awaiting certification from EPA and CARB. It's been there since 9/15. Anyway, I have a question for you if you don't mind. This car can travel "up to 30 miles" on electric only power. I live about 15 miles from my club so I would have a 30 mile round trip. The first mile is about half 25 and half 40 mph and then I enter onto the freeway (65 mph limit but often drive my current gas car around 80 mph) for the next 9 miles and finish up in a 50 mile zone the rest of the way. As I don't have the car yet in my possession, my query is informational only at this point. What I'm trying to determine is how should I drive the car to maximize the electric mileage without being ridiculous (i.e. wouldn't want to go below 60 mph on the freeway). Your thoughts appreciated.
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Old 10-28-2017, 08:24 PM
  #35  
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Originally Posted by 928 GT R View Post
gnocchi,

I was aware of the energy density advantage of polymer electrolytes but unaware of the interface issues with wetting deterioration above 4 volts between the anode and cathode. Your description makes intuitive sense.

The problem I see with LCO, NMC and NCA being used universally in EV's, is the lack of worldwide cobalt supply for the batteries themselves. Since cobalt is mostly produced as a by-product of copper mining, the supply is limited and it takes significant time and capital to bring large scale mines on-line.

Doubling the risk inherent with the shortage of cobalt is the fact that most of the world reserves are in the Democratic Republic of Congo (DRC). The DRC is the second most unstable jurisdiction on the planet and reliable supply is threatened by governmental and labor instability.

That said, Tesla/Panasonic has reportedly been able to reduce cobalt content to 6% in it's 18650 batteries from nearly 30% in the past.

Tesla's gigafactory is the worlds largest supplier of batteries and the new battery they are manufacturing now is called 2170 (21mm x 70mm) and while I do not know the cobalt content, they claim that it is 10-15 more energy dense but will continue to charge at 4.2 volts (same as the 18650) with less than 1% degradation per year. Pretty impressive!

At what percentage of cobalt content does a liquid electrode battery loose its energy density and how does cobalt content effect charging speed?

Thank you again for helping a rank amateur understand this fascinating new world!
Just a couple points of clarification:

The polymer only wets (in the sense of making intimate contact to all the nooks and crannies) to the anode and cathode surfaces the once. The details of micron-scale shape changes of the anode and cathode interfaces as the ions are transported aren't very predictable and don't tend to end up with the same result every time, hence resistance increases as there's now a gap for the ions to cross.

The voltage of a cell is set by the chemistry, 18650 vs 21700 (called 2170 by Tesla, but that specifies a 21mmD x 7.0mmT cell per LiIon naming conventions) is just the cell size, which corresponds to some extent with the volume of the jelly roll, which corresponds fairly closely with the amount of energy the cell can hold. An 18650 as used by Tesla has about 12.6Wh energy, and a 21700 as being used by R&D centers across the country has around 17Wh. That's a 47% increase in volume and a 35% increase in energy. The advantage of a 21700 is in the manufacturing time - for the same energy content in the pack, you need 35% fewer electrical connections to be made.

Pretty much everyone is reducing the cobalt content for the reasons you mentioned. Cobalt is "content", for lack of a better word, at several different ionization states, which means it can locally account for electrical property changes as the Li+ ions intercalate into the crystalline structure of the cathode. I'm not knowledgeable enough about the details to answer anything about when we begin to lose substantial energy density, sorry!

Originally Posted by SaratogaLefty View Post
Gnochi,
I've read this entire thread and I believe I really understand about 50% of the information conveyed. I have a 2018 Panamera 4 E Hybrid sitting at the San Diego Port awaiting certification from EPA and CARB. It's been there since 9/15. Anyway, I have a question for you if you don't mind. This car can travel "up to 30 miles" on electric only power. I live about 15 miles from my club so I would have a 30 mile round trip. The first mile is about half 25 and half 40 mph and then I enter onto the freeway (65 mph limit but often drive my current gas car around 80 mph) for the next 9 miles and finish up in a 50 mile zone the rest of the way. As I don't have the car yet in my possession, my query is informational only at this point. What I'm trying to determine is how should I drive the car to maximize the electric mileage without being ridiculous (i.e. wouldn't want to go below 60 mph on the freeway). Your thoughts appreciated.
I hope the EPA and CARB get their acts together soon! (ha. ha. ha.)

Basically, all of the "hypermiling" tricks apply - slow acceleration, decelerate appropriately to use regenerative braking the entire time (depending on settings), etc. You require the same wheel power to drive the same way whether it's ICE or xEV; the difference is with an ICE you're using on average about 30% of the energy content of the fuel for vehicle motion and with an EV you're using on average about 85% of the energy content of the battery pack for vehicle motion. In terms of chemical energy delivered to the engine, a 500hp engine is consuming closer to 1700hp in gasoline! (The amounts of power going to the wheels, the radiator, and the exhaust* are about identical (*note: this is why turbochargers work).)

That said, even if you don't only use electric power for the trip to the club, you're using less gas for the trip itself to environmental and pocket benefit, even if you drive it the same way you normally would. With a hybrid you don't need to worry so much about having an empty battery in the middle of nowhere. Just make sure to keep the gas tank full if you're going to mostly only use electric power for more than a few days.

My personal advice? Have fun driving it the way you enjoy! It's a Porsche, not a Prius
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Old 10-30-2017, 06:13 PM
  #36  
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EV's will stall in the coming decade without a energy storage revolution. There is also a fundamental Physics problem called electromigration that currently has no path to resolution. Biofuels/algae has more practical long term future potential. Not to mention how natural resource intensive EV production is. It's not practical, and IMO, EV will fizzle in the next 10 years.
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Old 10-31-2017, 01:29 AM
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@Airbag997 - unlikely.
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Old 10-31-2017, 01:36 AM
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more specification - how in particular do you expect electromigration to manifest itself in EV applications - and what about makes it infeasible from a EV deployment point of view and in what time frame do you expect this problem to manifest itself in the life cycle of a car?

and biofuels/algae don't solve the emissions problems - which is the primary driver of BEV adoption…china for example wants zero emission cars as a mandate.

do you have any evidence as to these assertions - or are you just opposed to EV's in general?
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Old 10-31-2017, 01:43 AM
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a quick read of https://en.wikipedia.org/wiki/Electromigration - show that this is a pervasive problem with all electronics and it is not specifically related to BEV's - rather all discrete IC based systems suffer from this condition - given that computers play as critical a role in gas/ICE applications I"m not sure why you feel this problem will in particular affect BEV's more substantially than ICE cars…other than the fact that it predicts all IC"s will eventually fail - the time frame of these failures is clearly with in acceptable limits for the typical lifecycle of a car or any other major purchase…

although I'd love to hear why you think Electromigration in particular will manifest itself with a vengeance in BEV applications where we already have examples of BEV cars remaining functional since 2010...please elaborate on how Electromigration will incapacitate EV's at a faster rate than ICE cars degrade, and why the same electronics in a ICE car degrading at the same rate won't lead to a similar lifespan for computer based fuel cars.
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Old 10-31-2017, 01:48 AM
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AC Induction motors, and DC motors also are not new techologies - and the basic operational capacity of industrial electric motors are measured in decades - we have examples of electric motors in use in elevators and industrial applications that exceed 50 years of continuous use - so the Electric Drive train doesn't seem subject to Electromigration, Batteries have a self life, but they can be replaced in about the same time frames as ICE motors and transmission with similar or less cost…

so are you referring to the computers controlling the BEV's - the same computers that control Gas cars as the failure mode for BEV's with regards to Electromigration..

the research I've done in the past 30 minutes on this topic doesn't yield any significant failure modes for which all of modern society is doomed given our dependance on computers and integrated circuits...that's an interesting discussion, but hardly unique to a transition to electrical based transportation.
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Old 10-31-2017, 09:44 AM
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Originally Posted by daveo4porsche View Post
@Airbag997 - unlikely.

There is already a major major charging infrastructure deficiency. Also, millenials don't own homes, and vast majority park in the streets.


EV is a fad. It's like BETAMAX before VHS. The government subsidies can't continue indefinitely. The true cost of EV's will come to light soon.
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Old 10-31-2017, 01:44 PM
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ahhh ok - troll.
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Old 10-31-2017, 02:40 PM
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Originally Posted by daveo4porsche View Post
ahhh ok - troll.


Ad hominem = simpleton
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Old 11-01-2017, 12:36 PM
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Originally Posted by gnochi View Post
Just a couple points of clarification:

The polymer only wets (in the sense of making intimate contact to all the nooks and crannies) to the anode and cathode surfaces the once. The details of micron-scale shape changes of the anode and cathode interfaces as the ions are transported aren't very predictable and don't tend to end up with the same result every time, hence resistance increases as there's now a gap for the ions to cross.

The voltage of a cell is set by the chemistry, 18650 vs 21700 (called 2170 by Tesla, but that specifies a 21mmD x 7.0mmT cell per LiIon naming conventions) is just the cell size, which corresponds to some extent with the volume of the jelly roll, which corresponds fairly closely with the amount of energy the cell can hold. An 18650 as used by Tesla has about 12.6Wh energy, and a 21700 as being used by R&D centers across the country has around 17Wh. That's a 47% increase in volume and a 35% increase in energy. The advantage of a 21700 is in the manufacturing time - for the same energy content in the pack, you need 35% fewer electrical connections to be made.

Pretty much everyone is reducing the cobalt content for the reasons you mentioned. Cobalt is "content", for lack of a better word, at several different ionization states, which means it can locally account for electrical property changes as the Li+ ions intercalate into the crystalline structure of the cathode. I'm not knowledgeable enough about the details to answer anything about when we begin to lose substantial energy density, sorry!



I hope the EPA and CARB get their acts together soon! (ha. ha. ha.)

Basically, all of the "hypermiling" tricks apply - slow acceleration, decelerate appropriately to use regenerative braking the entire time (depending on settings), etc. You require the same wheel power to drive the same way whether it's ICE or xEV; the difference is with an ICE you're using on average about 30% of the energy content of the fuel for vehicle motion and with an EV you're using on average about 85% of the energy content of the battery pack for vehicle motion. In terms of chemical energy delivered to the engine, a 500hp engine is consuming closer to 1700hp in gasoline! (The amounts of power going to the wheels, the radiator, and the exhaust* are about identical (*note: this is why turbochargers work).)

That said, even if you don't only use electric power for the trip to the club, you're using less gas for the trip itself to environmental and pocket benefit, even if you drive it the same way you normally would. With a hybrid you don't need to worry so much about having an empty battery in the middle of nowhere. Just make sure to keep the gas tank full if you're going to mostly only use electric power for more than a few days.

My personal advice? Have fun driving it the way you enjoy! It's a Porsche, not a Prius
This will be my fourth Porsche. I agree it is not a Prius and I don't intend to drive it like one but I was looking to get educated on how to maximize my electric distance when the wife is with me (can't be too aggressive when she is in the car) and your advice was very helpful.
I'm hoping you can help me with my real concerns about my car. The car went into the Body Shop on June 25th and didn't officially reach completion until July 25th but actually was stored for a couple of weeks during that time; then went to Emden on 8/4 and onto a ship on 8/16, arriving in San Diego port on 9/15 where it has been sitting ever since. While I'm concerned about the paint and tires (flat spots), I'm most concerned about the battery condition. Best case is it was last charged sometime in July; certainly not while on the ship or sitting in San Diego. So my question for you is do these batteries suffer any deterioration from not being charged for months at a time? Should I be concerned or just assume it will be covered by warranty should problems occur? Can't be an easy fix to replace a battery???
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Old 11-01-2017, 12:52 PM
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Originally Posted by SaratogaLefty View Post
This will be my fourth Porsche. I agree it is not a Prius and I don't intend to drive it like one but I was looking to get educated on how to maximize my electric distance when the wife is with me (can't be too aggressive when she is in the car) and your advice was very helpful.
I'm hoping you can help me with my real concerns about my car. The car went into the Body Shop on June 25th and didn't officially reach completion until July 25th but actually was stored for a couple of weeks during that time; then went to Emden on 8/4 and onto a ship on 8/16, arriving in San Diego port on 9/15 where it has been sitting ever since. While I'm concerned about the paint and tires (flat spots), I'm most concerned about the battery condition. Best case is it was last charged sometime in July; certainly not while on the ship or sitting in San Diego. So my question for you is do these batteries suffer any deterioration from not being charged for months at a time? Should I be concerned or just assume it will be covered by warranty should problems occur? Can't be an easy fix to replace a battery???
It's dependent upon the SOC (state of charge) the battery was left in over that period of time,
i.e. a very low SOC or at 100% are worse. Also, the temperate over that time period has an effect.
An extremely low SOC is the worst condition for the battery.
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