Mercedes Says Synthetic Fuel Isn’t Viable For The Auto Industry

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Originally Posted by y_p_w
The digital electronics will fail in spectacular fashion if the voltage drops. However, those are going to be powered off of a separate 12V system, which is going to have to stay operating or else all the controls are gone. And the actual electronics operate off of an even lower voltage. But reading as to how the system works - yeah they do all sorts of things when the battery weakens. This states that some who take a Tesla to a track usually make sure it's fully charged for the highest performance. Make sense. It doesn't sound like a bad thing. It's just dealing with the reality. https://forums.tesla.com/forum/forums/model-s-acceleration-slower-battery-depletes
Thank you again, I'm not sure if I am asking the question the right way or whether the EV industry is skirting it ( accidental or deliberate) so let me restate it All motors have a point where they simply must have a minimum power ( voltage and amperage) to physically turn in a circle and deliver their rated HP and torque. Ramping ( how fast they get there) is a different matter and with DC is almost always directly linked to the overall SOC of a "good battery" and that article you linked goes into that very well, again thank you. I want to know ( if the info is available, known or published) what the cut off is where the drive motor ( prime mover) simply will not function to BHP design. ( it simply doesn't have enough power to turn) This would be assumed to be a fully loaded and weighed down application as a service vehicle with payload. ( maybe not the race car or road trip application) Since we have been posting I have looked a bit and it seems this scenario is not adequately covered ( at least not that I can find)- I see all kinds of things talking around it but not directly addressing it. Whatever "that point" is ( assuming a good battery and functional EV), is the "anchor point" for all fitness for purpose testing for general use. It would determine minimum charge, load testing, fully loaded ranges, charge times and a whole lot more. Do you know where any of this type of information is? ( or who might) Thanks again
 
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Originally Posted by ABN_CBT_ENGR
Originally Posted by y_p_w
The digital electronics will fail in spectacular fashion if the voltage drops. However, those are going to be powered off of a separate 12V system, which is going to have to stay operating or else all the controls are gone. And the actual electronics operate off of an even lower voltage. But reading as to how the system works - yeah they do all sorts of things when the battery weakens. This states that some who take a Tesla to a track usually make sure it's fully charged for the highest performance. Make sense. It doesn't sound like a bad thing. It's just dealing with the reality. https://forums.tesla.com/forum/forums/model-s-acceleration-slower-battery-depletes
Thank you again, I'm not sure if I am asking the question the right way or whether the EV industry is skirting it ( accidental or deliberate) so let me restate it All motors have a point where they simply must have a minimum power ( voltage and amperage) to physically turn in a circle and deliver their rated HP and torque. Ramping ( how fast they get there) is a different matter and with DC is almost always directly linked to the overall SOC of a "good battery" and that article you linked goes into that very well, again thank you. I want to know ( if the info is available, known or published) what the cut off is where the drive motor ( prime mover) simply will not function to BHP design. ( it simply doesn't have enough power to turn) This would be assumed to be a fully loaded and weighed down application as a service vehicle with payload. ( maybe not the race car or road trip application) Since we have been posting I have looked a bit and it seems this scenario is not adequately covered ( at least not that I can find)- I see all kinds of things talking around it but not directly addressing it. Whatever "that point" is ( assuming a good battery and functional EV), is the "anchor point" for all fitness for purpose testing for general use. It would determine minimum charge, load testing, fully loaded ranges, charge times and a whole lot more. Do you know where any of this type of information is? ( or who might) Thanks again
Well - as a digital electronics guy, I'd point out that we have multiple mission-critical systems where the electronics have to function or people may die. Get on an airplane these days and it's all fly by wire. Get in a Tesla and it's all electronic controls at their heart, even with a steering wheel and pedals. Heck - the same goes for many gasoline powered cars. With that out of the way..... As far as all that other stuff goes, I'd assume that Tesla, GM, Ford, Chrysler, Nissan, Toyota, Honda, VW/Audi/Porsche, etc. and numerous bit players have already factored all that into their battery management systems. Dealing with a lower battery output is pretty common in all sort of electric-powered devices. However, unless there are white papers on it, these are likely to be trade secrets.
 
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Originally Posted by y_p_w
Well - as a digital electronics guy, I'd point out that we have multiple mission-critical systems where the electronics have to function or people may die. Get on an airplane these days and it's all fly by wire. Get in a Tesla and it's all electronic controls at their heart, even with a steering wheel and pedals. Heck - the same goes for many gasoline powered cars. With that out of the way..... As far as all that other stuff goes, I'd assume that Tesla, GM, Ford, Chrysler, Nissan, Toyota, Honda, VW/Audi/Porsche, etc. and numerous bit players have already factored all that into their battery management systems. Dealing with a lower battery output is pretty common in all sort of electric-powered devices. However, unless there are white papers on it, these are likely to be trade secrets.
I'll meet you in the middle on this one. In the beginning I operated on that same assumption that "somebody" did it and the information is "somewhere". (Being that I have sized and done motors and drives for almost 45 years, I know factually this is a very basic thing and available everywhere for every type of application- there is no "trade secret" to physics, only possibly an application of a device and even then there are only so many things that can be done to a motor) So, since these "experts" don't have any secret knowledge, technology or anything else the rest of us mechanical and electrical engineers don't have ( especially those in the motor business)- their "hiding" does look somewhat "suspicious". Now that I have spent time looking and asking ( and coming up basically empty) specifically on this most basic issue it forces me to consider that they in fact "have" considered it ( which from a design engineers perspective- it would have to be one of the first things they looked at) and having "seen the light" they didn't like the answer and are now obfuscating the answer for any number of reasons. I say that because that answer alone will be a critical determining factor ( but not the only I concede) on what markets and depth of penetration the EV can attain because this will put literally "hard stops' on what they can and cannot do compared to an ICE. ( not to mention cost, reliability, MTTR, total cost of ownership, etc.) So, I thank you for your efforts and if you ever locate anything along these lines on this specific issue to please let me know what it is.
 
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Originally Posted by ABN_CBT_ENGR
I'll meet you in the middle on this one. In the beginning I operated on that same assumption that "somebody" did it and the information is "somewhere". (Being that I have sized and done motors and drives for almost 45 years, I know factually this is a very basic thing and available everywhere for every type of application- there is no "trade secret" to physics, only possibly an application of a device and even then there are only so many things that can be done to a motor) So, since these "experts" don't have any secret knowledge, technology or anything else the rest of us mechanical and electrical engineers don't have ( especially those in the motor business)- their "hiding" does look somewhat "suspicious". Now that I have spent time looking and asking ( and coming up basically empty) specifically on this most basic issue it forces me to consider that they in fact "have" considered it ( which from a design engineers perspective- it would have to be one of the first things they looked at) and having "seen the light" they didn't like the answer and are now obfuscating the answer for any number of reasons. I say that because that answer alone will be a critical determining factor ( but not the only I concede) on what markets and depth of penetration the EV can attain because this will put literally "hard stops' on what they can and cannot do compared to an ICE. ( not to mention cost, reliability, MTTR, total cost of ownership, etc.) So, I thank you for your efforts and if you ever locate anything along these lines on this specific issue to please let me know what it is.
Again - a lot of this is still going to be proprietary. But if you want there are plenty of industry publications where Tesla and others have discussed how to deal with reduced battery performance. As you noted it would be about the first thing they would have to do. As far as batteries go - this is something that's never been a big secret. The EV battery systems have always sacrificed a little bit of range in exchange for longevity. Here's an article from the long-gone co-founder of Tesla from way back in 2006. This is all pretty basic and something many consumers understand about battery life.
Quote
https://www.tesla.com/blog/bit-about-batteries There is a huge difference in cycle life between a 4.2V/cell charge (defined by the manufacturers as "fully charged") and a 4.15V/cell charge. 4.15 volts represents a charge of about 95 percent. For this reduction of initial capacity (5 percent), the batteries last a whole lot longer. Unfortunately, further reduction of charge has a much smaller benefit on cycle life. Understanding this tradeoff, Tesla Motors has decided to limit the maximum charge of its cells to 4.15 volts, taking an initial 5 percent range hit to maximize lifetime of the pack. We also limit discharge of our battery pack to 3.0V/cell and will shut down the car when the batteries reach this level.
 
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Originally Posted by y_p_w
Again - a lot of this is still going to be proprietary. But if you want there are plenty of industry publications where Tesla and others have discussed how to deal with reduced battery performance. As you noted it would be about the first thing they would have to do. As far as batteries go - this is something that's never been a big secret. The EV battery systems have always sacrificed a little bit of range in exchange for longevity. Here's an article from the long-gone co-founder of Tesla from way back in 2006. This is all pretty basic and something many consumers understand about battery life.
I think this "may" be where they are obfuscating. (I did say may) because there is a mean power requirement where motors (AC and DC) will run with varying degrees of performance- that's not what I'm talking about because that would be between 1 & 100% efficiency and all that. I am asking what the 0-1% is where the motor either runs or cant. That's the minimum required power ( voltage and amps) for the motor to perform to design. That's a hard limit and a go=no-go state with no consideration of performance because its either zero or 1 Its no functionally different than a car out of gas. No sputtering or running lean- it just wont crank. That number relative to the SOC will be the determining factor whether the general public ( who needs the vehicle for more than just a toy or a niche market symbol) is going to find it adequate for their needs. That's the starting point of a lot of things, not to mention range of vehicle ( at full payload) how far the boat or camper and family can go, how deep in the woods, how much wood it can haul etc. Then it has to be factored as to what it will take to pull it out? ( a can of gas, a slave vehicle to ride along side and limp it out, an M-88 Tank recovery Vehicle, A skyhook air dropping a new battery?) Can you possibly direct me to where that information can be found. I can find lots that talk all around it and make vague references to all kinds of "stuff' but nothing that says the "the minimum power requirements for this thing to work is..." If anyone tries to hide behind that as being some kind of "proprietary number" when the working guy only has to look at a gas gauge then they really have a mountain to climb before the working public will ever accept them as anything more than a rich persons toy. Just like the greenies- real quick to tout solar panels and alternative methods- real slow to disconnect from the grid and show their own faith in it.
 
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I don't see why you seem to bring up full payloads or hauling a boat/camper. These are mostly passenger vehicles meant to get people from place to place. However, all these EVs give ample warning well before they shut down. It's really up to the user to determine if they really want to press their luck once it goes into reserve and starts giving loud warnings.
I doubt that they ever get to the point where the battery can't supply enough voltage/current to operate the motors. Eberhard said back in 2006 (probably regarding prototype Roadsters) that they simply shut down the system when the cells reach 3.0V. Of course it's all more complicated than that because they're AC motors requiring an inverter. Here's an owner discussion that talks about voltage and current demand. I guess many EV owners like to know how they work in detail. https://teslamotorsclub.com/tmc/threads/voltage-of-model-s-motors.50391/ I know that if I just needed to make a 10-15 one way commute I'd be fine with almost any EV. I personally wouldn't make an EV my only vehicle.
 
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Originally Posted by y_p_w
I don't see why you seem to bring up full payloads or hauling a boat/camper. These are mostly passenger vehicles meant to get people from place to place.
Fair question and nothing "sinister" or directed at you ( or any other individual for that matter) and I don't think we are as far apart in POV overall as we may be along the same lines. I bring it up because of the prevailing focus ( political and from certain elements for a variety of reasons) and the promulgation/promotion in certain areas that these will adequately replace the ICE at every level. As stated, I fully support the development/sales and all that of the EV (Tesla or whatever) in whatever markets it can sustain itself in to whatever buyer level can and wants to purchase them. So my queries are more focused on the former statement rather than the latter in this post.
Originally Posted by y_p_w
I know that if I just needed to make a 10-15 one way commute I'd be fine with almost any EV. I personally wouldn't make an EV my only vehicle.
I agree completely and I can see me eventually considering one to "experiment" with as well.
Originally Posted by y_p_w
However, all these EVs give ample warning well before they shut down. It's really up to the user to determine if they really want to press their luck once it goes into reserve and starts giving loud warnings.
Its not about pressing luck ( which in my mind if you play the odds and lose that's on you)- its about knowing where those lines are so they can be planned on and estimated accurately as the performance degrades so the person doesn't get caught "by surprise". No different than planning a camping trip and how many gas cans to carry. If the person chooses to "gamble then they get what they get- I personally don't like gambling. Thank you for your input
 
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