YOU: Fix the US Energy Crisis

[Topher925]

http://green.autoblog.com/2010/07/1...0-000-mile-[U][B]warranty[/B][/U]-for-volt-b/

No one is saying that the battery will actually last 8 years, only that GM will replace it when it dies.

 

[brainstorm]

What about tax deductions for businesses relative to the average commuting-distance for their employees? This would encourage them to relocate closer to where their employees live or hire more local employees to reduce their average commuting-distance.

Likewise, could government cover the closing costs and/or other fees associated with employees relocating closer to their work?

Could government somehow stimulate more mixed residential/commercial developments, such as incentives for apartment/condominium developers to make the ground level of their buildings commercial/retail or promoting mixed-zoning that increases job-density per unit population allowing more people to work close to home?

 

[mheslep]

No you wouldn't, your lithium ion battery wouldn't generate any power. [...]

From the NREL/Saft source Russ_Waters provided you previously. Lindzen's Battery Handbook also provides temperature data.

http://www.nrel.gov/vehiclesandfuels/energystorage/pdfs/evs17poster.pdf

We also have factual data on, e.g. the BMW E-Mini at cold temperatures. As we can see it manages to drive away, even when cold. Yes the range drops. No it is no prevented from starting by its 'BMS'.
http://si.wsj.net/public/resources/images/MK-BG780A_CarLi_G_20101017220417.jpg

Cycle life for a battery is generally readily available from its manufacturer. LG/CPI for example, http://www.compactpower.com/lithium.shtml
More here: http://www1.eere.energy.gov/vehiclesandfuels/pdfs/program/2008_energy_storage.pdf

Again, third time, I asked you to source your statement, not for general background reading on batteries.

Li batteries also have a life of only about 3 years before they are considered dead.

Which was probably some off the cuff comment based on experience with a laptop or the like. We are, of course, discussing batteries made for vehicle electric drive trains. Why not just retract or modify your statement?

 

[Topher925]

From the NREL/Saft source Russ_Waters provided you previously. Lindzen's Battery Handbook also provides temperature data.

The source that Russ provided only shows experimental data to 0'C and a theoretical model to -10'C. It also only addresses the effective capacity of the battery, not issues with degradation or specific power at those temperatures.

We also have factual data on, e.g. the BMW E-Mini at cold temperatures. As we can see it manages to drive away, even when cold. Yes the range drops. No it is no prevented from starting by its 'BMS'.

The graphic for the BMW E-mini only shows operation of the car to about 25'F of the ambient air temperature. Again, the question I originally stated was for a battery temperature of -20'F (~-30'C).

Again, third time, I asked you to source your statement, not for general background reading on batteries.

Ok, well for laboratory results for GenIII cells ("latest and greatest"), I again point you here:
http://www1.eere.energy.gov/vehicles...gy_storage.pdf
Page 29, Figure III-3
Page 30, Figure III-4

For blanket statements supporting my general point that Li batteries have poor cycle life you can look in just about any book or respectable resource. But since I have to provide a source:

Lithium batteries for EVs are far from commercialization
Lithium metal polymer suffers from poor cycle life. A stiffer solid polymer electrolyte with significantly improved ionic conductivity at room temperature is required.

www.ornl.gov/sci/sp/Pres/Duong.ppt[/URL]

If you need hard experimental data from battery manufacturers or OEMs, well I'm obviously not going to have it as that information is almost always proprietary. The majority of my practical knowledge of batteries and the vehicles that use them come from primary sources.

[QUOTE]
Which was probably some off the cuff comment based on experience with a laptop or the like. We are, of course, discussing batteries made for vehicle electric drive trains. Why not just retract or modify your statement?[/QUOTE]

My experience comes from classmates and colleagues that work at either A123 Systems or General Motors and work on the Chevy Volt. My experience also comes from classes I have taken about battery and hybrid systems as well as my general knowledge of electrochemical storage and conversion devices that I've obtained from my university research. I will not retract or modify my statement because there is nothing wrong with it and you have yet to prove otherwise.

 

[mheslep]

The source that Russ provided only shows experimental data to 0'C and a theoretical model to -10'C.

So? That they "dont work" cold is your claim. You have information showing the model suddenly fails at -30C (-20F)?

It also only addresses the effective capacity of the battery, not issues with degradation or specific power at those temperatures.

The model does. Spec power is ~linearly related to capacity per the model NREL shows on slide 3. That is, if capacity drops by 10%, spec power drops 10%.

Ok, well for laboratory results for GenIII cells ("latest and greatest"), I again point you here:
http://www1.eere.energy.gov/vehicles...gy_storage.pdf
Page 29, Figure III-3
Page 30, Figure III-4

Did you review the charts? They say what? That capacity degrades significantly per cycle with long term 55C / 131F usage, and very slowly at moderate temperatures. The GM Volt and Tesla batteries for example will be/are temperature controlled, hot and cold.

For blanket statements supporting my general point that Li batteries have poor cycle life you can look in just about any book or respectable resource.

No I don't think so, my https://www.amazon.com/dp/0071359788/?tag=pfamazon01-20 doesn't, and I've provided other sources showing the opposite previously in other threads.

But since I have to provide a source:

www.ornl.gov/sci/sp/Pres/Duong.ppt[/URL][/QUOTE]
You noted the source says [I]Lithium [B]metal polymer[/B] suffers from poor cycle life.[/I]? So? The forthcoming Volt, Leaf, iMiev, E-Mini, iMiev do not use metal poly.

Also from the EERE Duong,2007 ppt:
Slide 7: [QUOTE=Duong]Life: projections of 10-15 years are based on limited data[/QUOTE]
Slide 6:[QUOTE=Duong, ][small battery]CD: Energy scaled for range (10-40 miles), 5,000 deep discharge cycles
[large battery]CD only: Energy scaled for 100+ mile range, 1,000+ deep discharge cycles[/QUOTE]
CD = Charge depletion, ie discharge mode. The first gives 200,000 miles per battery, the second 100,000 miles.

Duong's statement that "Conventional" Li Ion HEV batteries are ripe for commercialization but the pure BEV batteries are not seems to be a statement about their cost, not their calendar or cycle life.
[quote]If you need hard experimental data from battery manufacturers or OEMs, [/quote]Nope, third party tests will do, such as the EERE figures above. I've provided national lab figures myself in another thread.
[quote]The majority of my practical knowledge of batteries and the vehicles that use them come from primary sources. [/quote]Which primary sources? If you can't provide them, can you name them?

[quote]I will not retract or modify my statement because there is nothing wrong with it and you have yet to prove otherwise.[/QUOTE]I'm only interested what you can clearly show through references. I don't have to prove your "about 3 years" claim false, though I can. The burden is on you to prove it true.

 

[Redbelly98]

From the NREL/Saft source Russ_Waters provided you previously. Lindzen's Battery Handbook also provides temperature data.

http://www.nrel.gov/vehiclesandfuels/energystorage/pdfs/evs17poster.pdf

Since the data go down to 0 C, I'm leery of using the model to extrapolate much below that. I would be curious to see actual data for -20 or even -30 C (-4, -22 F)

 

[mheslep]

Since the data go down to 0 C, I'm leery of using the model to extrapolate much below that. I would be curious to see actual data for -20 or even -30 C (-4, -22 F)

Yes I'd like to see the data too. Meanwhile, I'm much more leery of unqualified claims that a Li ion battery completely fails at those temperatures without any support what so ever (data or model).

 

[Topher925]

So? That they "dont work" cold is your claim. You have information showing the model suddenly fails at -30C (-20F)?

Do you have information that shows it doesn't? Its your source, not mine. You can't ask me to provide sources that completely prove my point and then just make yourself exempt of the same standard.

Did you review the charts? They say what? That capacity degrades significantly per cycle with long term 55C / 131F usage, and very slowly at moderate temperatures. The GM Volt and Tesla batteries for example will be/are temperature controlled, hot and cold.

What? The charts say absolutely nothing about capacity, they show the increase in ASI (Area Specific Impedance) over time. The purpose of those charts was to show that on average the Gen II and Gen III cells had an increase of ASI of about 25% within 45 weeks. The higher temperature tests are even much higher than that.

No I don't think so, my https://www.amazon.com/dp/0071359788/?tag=pfamazon01-20 doesn't, and I've provided other sources showing the opposite previously in other threads.

It appears that Linden is making the comparison between Li-ion to other batteries in general (like for commercial products) and not in the application of electrical vehicles. That book also appears to be very outdated and rather fuzzy when it comes to some of their statements. The fact that they don't really mention anything about Li battery safety and things like thermal runaway throws up a flag.
Linden, sections 35.42-43 Figures 35.45 and 35.46 clearly show severe (greater than 80% SOC) capacity reduction with less than 1,000 cycles. Keep in mind Figure 35.46 is data for a C/LiMn2O4 type battery which is the same anode and cathode materials used LG CPI batteries.

You noted the source says Lithium metal polymer suffers from poor cycle life.? So? The forthcoming Volt, Leaf, iMiev, E-Mini, iMiev do not use metal poly.

I only added the Lithium Metal Poly part because a lot of people think that technology can lead to a significant cost reduction and think its the future of EV's. But you're right, no one uses them for vehicle apps as far as I know so I'll restate it;

Lithium batteries for EVs are far from commercialization

Also from the EERE Duong,2007 ppt:
Slide 7:
Slide 6:
CD = Charge depletion, ie discharge mode. The first gives 200,000 miles per battery, the second 100,000 miles.

Slide 6 clearly states "Energy scaled for 100+ mile range, 1,000+ deep discharge cycles" for EVs, the 5,000 cycles is for PHEVs. 1,000 cycles is just a little more than 2.5 years in estimated calendar life.

Duong's statement that "Conventional" Li Ion HEV batteries are ripe for commercialization but the pure BEV batteries are not seems to be a statement about their cost, not their calendar or cycle life.

No, I don't think it is.

Major R&D is focused on suppressing dendrite formation and stabilizing the lithium interphase
Additional barriers include cost, low specific energy and poor cycle and calendar life.

www.ornl.gov/sci/sp/Pres/Duong.ppt[/URL][QUOTE]Which primary sources? If you can't provide them, can you name them?[/QUOTE]

No, I'm not going to ask them for permission to serve as my primary source for someone I'm having a debate with on the internet.

So anyway, back to the temperature thing...

Linden 35.41, Figure 35.43 Approximate C-rate discharge of an 18650-type C/LiCoO2 battery at various temperatures...

The BMS and power electronics of an EV generally operate between a voltage of about 400 to 250V where 250V is the minimum operating voltage. This means that you will generally want your module OCV at around 350ish volts due to the voltage drop and hike when discharging and recharging the battery. So, using these ballpark numbers and a IR of 5mOhm ([url]http://www.a123systems.com/a123/products[/url] minus a little for err) and the data from the figure from Linden we can do a quick calculation.

At 25'C -> 350V/4.2 = 83 cells per module (~349V)

At -20'C -> 83*2.9V = 240.7V

10 Volts below that of the minimum operating voltage of the power electronics, which in other words will make the BMS turn off the battery making it "not work" as one of my previous sources stated. You could argue that I just pulled this 250V* number out of the air (which I didn't) but keep in mind I am just talking close OCV here. This doesn't include the temperature effects on current output due to increased impedance from the electrolyte and diffusion of Li ions through the SEI.
[URL]http://www.uqm.com/pdfs/HiTor%2010.13.08.pdf[/URL]

How do you think the Volt's batteries handles cold weather?
[QUOTE]The battery needs a minimum temperature of between 0 °C and 10 °C (32 °F and 50 °F) to be used and when the Volt is plugged in the battery will be kept warm enough so that it can be used immediately when the Volt is unplugged. If the Volt is kept unplugged and the temperature of the battery is below the minimum temperature, the gasoline engine will run until the battery warms up. This temperature regulation is done since electro-chemical batteries have degraded performance when they are very cold.[/QUOTE]
[url]http://en.wikipedia.org/wiki/Chevrolet_Volt#Specifications[/url]

[QUOTE]Another of the weaknesses of electro-chemical batteries is degraded performance when they are very cold. GM engineers have devised battery conditioning algorithms to help overcome this...if you're not plugged in and the battery is not conditioned and we've got to deal with the elements, right now we're thinking 0-10°C we won't use the battery.[/QUOTE]
[URL]http://greenfuelsforecast.com/ArticleDetails.php?articleID=686[/URL]

So, if the Volt can't use its batteries at 10'C and below, what is it that's going to allow a typical EV to do so?

 

[mheslep]

It appears that Linden is making the comparison between Li-ion to other batteries in general (like for commercial products) and not in the application of electrical vehicles.

Yes, just as the title indicates - a general battery handbook.

That book also appears to be very outdated

Yes it is a bit old, and not up with the latest improvements.
and rather fuzzy when it comes to some of their statements. The fact that they don't really mention anything about Li battery safety and things like thermal runaway throws up a flag.[/quote]Linden's text is a bible in the industry, cited as a basic reference in papers again and again. Thermal runaway is referenced throughout.

Linden, sections 35.42-43 Figures 35.45 and 35.46 clearly show severe (greater than 80% SOC) capacity reduction with less than 1,000 cycles. Keep in mind Figure 35.46 is data for a C/LiMn2O4 type battery which is the same anode and cathode materials used LG CPI batteries.

Good figures for discussion. Figure 45 is old Cobalt chemistry (laptops) and I agree it is important to note the difference w/ C/LiMn2O in Figure 46. Those figures however are for full discharge, 100% DoD cycles. The GM Volt, which uses LG batteries, does not swing through 100% DoD, more like 50-60%, as you no doubt know. See then Linden page 35.48 and figure 35.55 , which shows data for a 30% DoD case yielding "cycle lives between 55,000 and 137,000 cycles" [italics mine]. Then, the other pure BEVs like the the Leaf/Fluence which will do 100% DoD are using newer nano - particle anodes (not found in Linden) which brings the cycle life up considerably.

 

[mheslep]

So anyway, back to the temperature thing...

Linden 35.41, Figure 35.43 Approximate C-rate discharge of an 18650-type C/LiCoO2 battery at various temperatures...

The BMS and power electronics of an EV generally operate between a voltage of about 400 to 250V where 250V is the minimum operating voltage. This means that you will generally want your module OCV at around 350ish volts due to the voltage drop and hike when discharging and recharging the battery. So, using these ballpark numbers and a IR of 5mOhm (http://www.a123systems.com/a123/products minus a little for err) and the data from the figure from Linden we can do a quick calculation.

At 25'C -> 350V/4.2 = 83 cells per module (~349V)

At -20'C -> 83*2.9V = 240.7V

The packs can be put together in most any series / parallel combination that yields at least a couple hundred volts and can be efficiently converted to motor voltage from there, but that's beside the point. The ~2.9VDC figure Linden shows in Fig 43 is the -20degC full 1C discharge voltage. This is not the discharge rate required to roll out of a parking spot on a -20degC morning, rather ~0.1C will do that, with 10X less I*R voltage drop. So full acceleration power won't be available at startup, but then I don't put my foot to the floor right away w/ my gasoline vehicle either on -20degC days.

I'm sure you noted the capacity data in Figure 35.44 down to -20degC, maybe a 20% loss. So what we have is an EV that starts and drives a way even on the coldest mornings, but loses some range and top end power. Thus I think it was a dumb move for the Leaf/E-mini/Fluence not to include some kind thermal management on their battery.

 

[Topher925]

Thermal runaway is referenced throughout.

Show me where it gives more than two reasons for thermal runaway.

Good figures for discussion. Figure 45 is old Cobalt chemistry (laptops) and I agree it is important to note the difference w/ C/LiMn2O in Figure 46. Those figures however are for full discharge, 100% DoD cycles. The GM Volt, which uses LG batteries, does not swing through 100% DoD, more like 50-60%, as you no doubt know.

No, I don't know that because its not true. BTW, I don't think anyone uses Co, not even for laptops. Its been slated to be too dangerous for consumer products.

The Volt's 375 lb (170 kg), 220-cell lithium-ion battery (Li-ion) pack is anticipated to store 16 kW·h of energy,[1][67] but will be restricted (in software) to use only 10.4 kW·h of this capacity to maximize the life of the pack. It will only be allowed to charge to 90% of full capacity and to discharge only to approximately 25% SoC before the engine cuts in and maintains the charge near the lower level.

http://en.wikipedia.org/wiki/Chevrolet_Volt#Battery

See then Linden page 35.48 and figure 35.55 , which shows data for a 30% DoD case yielding "cycle lives between 55,000 and 137,000 cycles" [italics mine].

I don't have the book with me at the moment so I will have to look at the figures again later tonight. Regardless, BEVs will go beyond 30% DoD in order to meet their distance requirements.

Then, the other pure BEVs like the the Leaf/Fluence which will do 100% DoD are using newer nano - particle anodes (not found in Linden) which brings the cycle life up considerably.

No they are not.

Type: Laminated lithium-ion battery
Total capacity (kWh): 24
Power output (kW): Over 90
Number of modules: 48

Battery pack contents:
-Positive electrodes – Lithium manganate
-Negative electrodes – Carbon
-Cells
-Modules
-Assembly parts

http://green.autoblog.com/2010/05/2...eaf-battery-pack-including-how-recharging-sp/

The only material that can use nanoparticles on the negative electrode is lithium titanate oxide which used by manufacturers like Altair Nano. However, using Li2TiO3 drops the OCV considerably reducing the specific energy so much that those kinds of batteries are not suitable for EVs (~50Wh/kg).
http://www.targetdoc.com/viewer.asp?b=546&k=lchr4714LC&bhcp=1

I'm surprised you haven't mentioned this about the Leaf yet;

Battery life: After 10 years, the battery is expected to have 70-80 percent of its original storage capacity

http://green.autoblog.com/2010/05/2...eaf-battery-pack-including-how-recharging-sp/

 

[Topher925]

The packs can be put together in most any series / parallel combination that yields at least a couple hundred volts and can be efficiently converted to motor voltage from there, but that's beside the point.

So you think EV engineers should devise a system to rewire the modules depending on how cold the batteries are? Sounds expensive.

The ~2.9VDC figure Linden shows in Fig 43 is the -20degC full 1C discharge voltage. This is not the discharge rate required to roll out of a parking spot on a -20degC morning, rather ~0.1C will do that, with 10X less I*R voltage drop. So full acceleration power won't be available at startup, but then I don't put my foot to the floor right away w/ my gasoline vehicle either on -20degC days.

So the moment you pull out of your driveway you're going to keep going 1mph? How long and how much energy do you think it takes to heat up a 500kg battery? I would bet that in a practical case it would take a while even considering the battery to be at full power output just to heat itself up from -20'C in a reasonable amount of time. Its not like you're heating an internal combustion engine which has a smaller mass and where 75% of the energy you're using is being turned to heat.

I'm sure you noted the capacity data in Figure 35.44 down to -20degC, maybe a 20% loss. So what we have is an EV that starts and drives a way even on the coldest mornings, but loses some range and top end power. Thus I think it was a dumb move for the Leaf/E-mini/Fluence not to include some kind thermal management on their battery.

No I don't recall without the book in front of me, but what does capacity have to do power output in this case? And if this is true, why can't the Volt just drive away using only its battery when its 0'F outside? If the Leaf uses the same chemistry, why can it operate at those temperatures but the Volt cant?

The nixing of the TMS for the batteries wasn't necessarily a dumb move, it just wasn't a very smart one. Nissan is building the Leaf to a price point and in order to reach that point they have to have an air cooled battery. Will this shorten the life and reduce the performance of the battery? Most definitely. Will there be potential future lawsuits if the cells experience thermal runaway? Yeah, probably, but I bet Nissan is going to sell a lot of these cars.

 

[mheslep]

Show me where it gives more than two reasons for thermal runaway.

Search the Amazon reference for "thermal runaway" if you like.

The GM Volt, which uses LG batteries, does not swing through 100% DoD, more like 50-60%, as you no doubt know.

No, I don't know that because its not true.

http://en.wikipedia.org/wiki/Chevrolet_Volt#Battery

90-30 = a 60% DoD swing.

I'm surprised you haven't mentioned this about the Leaf yet;

Battery life: After 10 years, the battery is expected to have 70-80 percent of its original storage capacity

http://green.autoblog.com/2010/05/2...eaf-battery-pack-including-how-recharging-sp/

Yes and Nissan also warranties the battery for 8 years/100,000 miles. You knew this, and accepted it all along? Yet you still made the "about 3 years before they are considered dead" claim?

 

[mheslep]

No I don't recall without the book in front of me, but what does capacity have to do power output in this case?

The battery model is relatively simple for a first approximation as several of the references have shown: a simple idea voltage source at ~4.2V connected to the load via an internal (effective) battery resistance, with a dependency on state of charge, temperature, and life cycle as we have seen. Capacity then is the total energy delivered by the battery to a load which is not consumed by the I^2 * R losses, and power is simply the rate of delivery of that energy, also limited by voltage drop across the internal resistance.

And if this is true, why can't the Volt just drive away using only its battery when its 0'F outside? If the Leaf uses the same chemistry, why can it operate at those temperatures but the Volt cant?

The Volt's battery probably could, but as we've discussed driving around with a cold battery and thus high internal resistance wastes energy unnecessarily on internal losses and cuts the range significantly. GM wants to be able to say, I believe, that battery operation range is at least close to 40miles, always. So it makes perfect sense for the Volt's controller to use the combustion engine first to warm up the battery, given the Volt has that option. Same probably goes for hot temperatures in the Volt to avoid life time degradation - cool it off first.

 

[mheslep]

The ~2.9VDC figure Linden shows in Fig 43 is the -20degC full 1C discharge voltage. This is not the discharge rate required to roll out of a parking spot on a -20degC morning, rather ~0.1C will do that, with 10X less I*R voltage drop. So full acceleration power won't be available at startup, but then I don't put my foot to the floor right away w/ my gasoline vehicle either on -20degC days.

So the moment you pull out of your driveway you're going to keep going 1mph?

The tractive power required to travel 70mph vs 10mph in a sedan is about http://www.inference.phy.cam.ac.uk/withouthotair/cA/page_256.shtml"

How long and how much energy do you think it takes to heat up a 500kg battery?

http://nissan-leaf.net/2010/05/27/nissan-leaf-battery-specifications/", Fluence is 250kg, frame and all, only the electrolyte and separator matter, and as the curves show it need be warmed only only to ~ 0 degC or so.

I would bet that in a practical case it would take a while even considering the battery to be at full power output just to heat itself up from -20'C in a reasonable amount of time. Its not like you're heating an internal combustion engine which has a smaller mass and where 75% of the energy you're using is being turned to heat.

Well consider, for example, that the total battery pack is providing, say, 100A through an elevated internal resistance when cold of 10 milliohm. That's one KW of heating applied exactly where its needed. Yes the Leaf will be sluggish in extreme cold, and I imagine we'll hear people griping about it giving the car a bad rep. I suppose, as you say, Nissan's going for cheap, not good all weather performance. Of course some people are already used to taking additional measures in the extreme cold - Canadians and Scandinavians plugging in engine block heaters overnight.

 

[Topher925]

Search the Amazon reference for "thermal runaway" if you like.

I don't need to. I already searched the book itself. I couldn't even find where it states all of the root sources of thermal runaway.

Yes and Nissan also warranties the battery for 8 years/100,000 miles. You knew this, and accepted it all along? Yet you still made the "https://www.physicsforums.com/showpost.php?p=2980109&postcount=656"" claim?

Did I know that all along, yes. Did I "accept" it, a very strong No. There's a lot of controversy and suspicion over Nissan and the battery they put in the Leaf. 1,2,3 Stating that their battery can last essentially 10 years and even do it without a TMS is quite the statement, especially from a company that can't even build a much simpler competitive hybrid. Nissan has to buy their hybrid powertrains from their competitor, Toyota.4

1. http://www.dailytech.com/Tesla+CEO+...imitive+Boasts+About+Model+S/article19286.htm
2. http://gm-volt.com/2010/01/28/nissan-taking-shortcut-on-leaf-battery-no-thermal-management-system/
3. http://www.technologyreview.com/energy/26832/?p1=A1
4. http://en.wikipedia.org/wiki/Hybrid_Synergy_Drive

 

[Topher925]

Capacity then is the total energy delivered by the battery to a load which is not consumed by the I^2 * R losses, and power is simply the rate of delivery of that energy, also limited by voltage drop across the internal resistance.

Ok? Still not seeing the connection here. You can have a relatively small or large I and not have a big change in capacity, but it doesn't really work the other way around. Also, when Li ion batteries get really cold, their power output and perceived capacity is time dependent as the reaction is limited by diffusion of Li⁺ through the SEI.

The Volt's battery probably could, but as we've discussed driving around with a cold battery and thus high internal resistance wastes energy unnecessarily on internal losses and cuts the range significantly. GM wants to be able to say, I believe, that battery operation range is at least close to 40miles, always.

Do you have any way to support this claim? The sources I pointed out very clearly state it to be a performance issue suggesting that its an issue with power and not one of capacity.

 

[Topher925]

The tractive power required to travel 70mph vs 10mph in a sedan is about http://www.inference.phy.cam.ac.uk/withouthotair/cA/page_256.shtml"

Alright. But what's your point other than traction power increases with speed?

http://nissan-leaf.net/2010/05/27/nissan-leaf-battery-specifications/", Fluence is 250kg, frame and all, only the electrolyte and separator matter, and as the curves show it need be warmed only only to ~ 0 degC or so.

OK, either way 300kg is a large mass to heat, especially when the battery is air cooled and designed to have efficient convective heat transfer. Even if you assume the battery is made entirely of something like aluminum, that's about 1.5kWh to raise the battery from -20'C to 0'C. Or in other words, about 12% of your usable battery capacity.

And no, its not just the separater and electrolyte that matter, the electrodes, especially the negative electrode, matter as well. Its not like you can just heat one without the other anyway.

Well consider, for example, that the total battery pack is providing, say, 100A through an elevated internal resistance when cold of 10 milliohm. That's one KW of heating applied exactly where its needed. Yes the Leaf will be sluggish in extreme cold, and I imagine we'll hear people griping about it giving the car a bad rep. I suppose, as you say, Nissan's going for cheap, not good all weather performance. Of course some people are already used to taking additional measures in the extreme cold - Canadians and Scandinavians plugging in engine block heaters overnight.

See comment above. At 1kW of heat, its going to take well over an hour to heat up that battery. Although 10mOhm for resistance of an entire battery pack sounds pretty small to me. Were you referring to just a single cell or module?

 

[mheslep]

Alright. But what's your point other than traction power increases with speed?

Right, required traction power increases with speed. The point is that the vehicle won't need anywhere near the sustained full power for which the EV battery was designed until it hits the highway, and then only at high speed.

OK, either way 300kg is a large mass to heat, especially when the battery is air cooled and designed to have efficient convective heat transfer. Even if you assume the battery is made entirely of something like aluminum, that's about 1.5kWh to raise the battery from -20'C to 0'C. Or in other words, about 12% of your usable battery capacity.

And no, its not just the separater and electrolyte that matter, the electrodes, especially the negative electrode, matter as well. Its not like you can just heat one without the other anyway.

See comment above. At 1kW of heat, its going to take well over an hour to heat up that battery.

The heat comes only from the active part of the battery, and there will be a heat flux down a temperature gradient between the active battery area and the remainder. Let's look at the details.

As we discussed, the power limitation is due to ion diffusion temperature sensitivity, in this case Li ions. Thus we need look at only that which contains Lithium and is actively transferring ions, namely most of the electrolyte and the surface of the cathode. The electrolyte is about http://www.transportation.anl.gov/pdfs/TA/149.pdf" for one cell. Sixty such 100Ah cells at ~3.5kg/cell make up a 24KWh - 100 mile EV pack, for ~210kg, the rest is infrastructure (wiring,housing,etc), leaving maybe only 40kg of active material. The electrolyte is a salt, say LiPF6; I don't know its specific heat capacity but assuming it is similar to other salts at ~0.9 kj/kg-K, we have 0.9 *~20kg * 20degK / 1kW = 720s, i.e. a 20deg C rise in 12 minutes. Yes some of the heat is dissipating away to the rest of the battery, but via a salt and non-metal electrodes I'd guess that's a down ~20degC temperature gradient to the outside housing at max power.

 

[Topher925]

Right, required traction power increases with speed. The point is that the vehicle won't need anywhere near the sustained full power for which the EV battery was designed until it hits the highway, and then only at high speed.

And what about acceleration and driving up hills? What if I live in San Fransisco? Not everyone is driving Ms. Daisy.

The heat comes only from the active part of the battery, and there will be a heat flux down a temperature gradient between the active battery area and the remainder. Lets look at the details...some of the heat is dissipating away to the rest of the battery, but via a salt and non-metal electrodes I'd guess that's a down ~20degC temperature gradient to the outside housing at max power.

One of the details you didn't include is the heat transferred to the electrodes and current collectors. The geometry of the electrolyte and seperater obviously provide a large area of contact to the electrodes providing a lot of surface area per volume for heat transfer. The electrodes are constructed from graphite and spinel, both materials which have very good thermal conductivity. The current collectors are constructed from aluminum and possibly copper, again very good thermal conductivity. Its not realistic to make the assumption that only the electrolyte and seperater are generating heat and mostly only heating themselves, especially with a 20'C temperature gradient. To be realistic, you should at least consider the entire mass of the battery itself, 210kg, to account for convective heat transfer to the surroundings.

 

[mheslep]

I don't need to. I already searched the book itself. I couldn't even find where it states all of the root sources of thermal runaway.



Did I know that all along, yes. Did I "accept" it, a very strong No. There's a lot of controversy and suspicion over Nissan and the battery they put in the Leaf. 1,2,3 Stating that their battery can last essentially 10 years and even do it without a TMS is quite the statement, especially from a company that can't even build a much simpler competitive hybrid. Nissan has to buy their hybrid powertrains from their competitor, Toyota.

Oh I agree, a lack of a thermal system is going to be big problem, and the Leaf is going be all over the place in performance as a consequence. Some owner in San Jose, Ca w/ 80F 365 days a year will get 10 years, but some other guy in Vegas who drives hard in 110F summers may get half. That's completely different from the blanket statement "Li batteries also have a life of only about 3 years before they are considered dead", especially in the context of the recent GE buy of GM Volts which do have TMSs.

1. http://www.dailytech.com/Tesla+CEO+...imitive+Boasts+About+Model+S/article19286.htm
2. http://gm-volt.com/2010/01/28/nissan-taking-shortcut-on-leaf-battery-no-thermal-management-system/
3. http://www.technologyreview.com/energy/26832/?p1=A1

Thanks for these references. The bit from today's TR story I didn't know and is especially interesting:

Nissan recommends a cold weather package that includes a battery heater, but this doesn't come as standard. And the option is not available for the first Leafs to come off of the assembly line, and it cannot be added to a car later. If the Leaf pack gets too cold, or too hot, it enters a limited power mode, which restricts acceleration and top speed.

 

[mheslep]

And what about acceleration and driving up hills? What if I live in San Fransisco? Not everyone is driving Ms. Daisy.

If the location is SF then an EV will never see -20C, nor anywhere else in Ca outside the mountains. Let's not turn this around as if I have claimed all EV/PHEV's will work perfectly without downsides, all the time, everywhere. As I've said, an EV/PHEV without TMS in extreme cold weather is going to be sluggish until it warms itself up. I objected up front only to absolute claims that "EV's still don't work in cold weather", and then digging in deeper with claims that an EV won't "start" in the cold, and then won't drive away from the parking lot if started.

One of the details you didn't include is the heat transferred to the electrodes and current collectors. The geometry of the electrolyte and seperater obviously provide a large area of contact to the electrodes providing a lot of surface area per volume for heat transfer. The electrodes are constructed from graphite and spinel, both materials which have very good thermal conductivity. The current collectors are constructed from aluminum and possibly copper, again very good thermal conductivity.

I did consider the electrodes for heat flow and discounted them. What's important is not that the electrodes are good thermal conductors, but that salts (solid) are relatively very poor thermal conductors - probably 20-30x worse than metals, and thus won't quickly give up their heat. Imagine a hot brick (poor thermal conductor). Embedding several metal rods in it won't cause it to cool markedly faster.

 

[mheslep]

I came across these sticker prices for the Nissan Leaf EV vs a comparably sized gasoline vehicle, the Chevy Cruze, and wanted to extend them to ten year cost of ownership. Both are 5 door, 5 seat smallish vehicles.

The Leaf EV price of $26,380 is after the $7500 tax credit.

Here's ten year total cost of vehicle plus fuel/electricity, with the Cruze at $1457/yr and the Leaf at $396/yr:
Leaf: $30,340
Chevy Cruze: $31,565
Prius: $30,960

Maintenance:
For other maintenance, both vehicles will both need tires, but the Leaf needs no: oil changes, transmission work, radiator flushes, fuel/water pumps, little or no brake work, etc, etc. On experience, I'd guess that's $400/yr (not including tires) for a small vehicle like the Cruze, or $4000/ten years. The Leaf is going to need a new battery at ten years; replacement cost is complicated ten years out. Currently the battery is ~$10,000-12,000; by 2020 probably $5000. But then it may not make sense to buy a brand new ten year (non-swappable) battery for a ten year old car, so perhaps a half-life battery would do, if such a thing could be bought on the market at that time.

 

[brainstorm]

The solution to energy crisis has been discovered and I have already invested: the Snuggie (blanket with sleeves).

As for the problem with heating electric cars, how much propane would it take to keep an electric car at 70F for a 1-hour commute?

 

[mheslep]

The solution to energy crisis has been discovered and I have already invested: the Snuggie (blanket with sleeves).

As for the problem with heating electric cars, how much propane would it take to keep an electric car at 70F for a 1-hour commute?

Which day of the week?

 

[brainstorm]

Which day of the week?

Lol. Sunday morning at 11am when it's 40F with no clouds and the car is driving due east 50% of the time in Chicago with a 50/50 mix of shaded and unshaded routes.

 

[mheslep]

Was reviewing some of the posts upthread on nuclear costs and thought this apropos to recent news:

Regards the Olkiluoto EPR, any word from the industry on a) the expected final cost of the plant and b) the primary reasons for the cost overruns and schedule delays? Pop press now says 4.5B Euro / $5.7B for the 1,600MW plant, won't come online until 2012 (permit granted in early 2005)
http://www.guardian.co.uk/environment/2008/oct/18/nuclearpower

Update two years on:

But the Olkiluoto-3 reactor has had a deeply troubled history. Originally slated to cost around $4 billion (€3 billion), its price tag has nearly doubled to $7.2 billion (€5.3 billion). And it is four years behind schedule.

http://online.wsj.com/article/SB10001424052748703865004575648662738551250.html?KEYWORDS=Olkiluoto

That's one reactor being built at an existing nuclear plant. Good grief.

 

[mheslep]

http://online.wsj.com/article/SB10001424052748704584804575644773552573304.html") for around town deliveries, and not for green wash, but because they pay off:

[...]Staples Inc., the Frito-Lay division of PepsiCo, FedEx Corp., AT&T Inc. and a few other companies have begun purchasing electric delivery trucks. Proponents say they make more sense in many ways than electric cars. That's because delivery trucks generally drive short, defined routes each day, which are better suited to the limited range of battery power.

Staples has ordered 41 trucks from Smith Electric Vehicles of Kansas City, Mo., and will start receiving them in January. There is "a real strong chance we'll make a second order for 40," Mr. Payette said.

The trucks, which have a top speed of about 50 mph and can carry 16,000 pounds, cost about $30,000 more than a diesel, but Staples expects to recover that expense in 3.3 years because of the savings inherent in the electric models, Mr. Payette said.

Interestingly it appears maintenance is becoming one of the deciding factors for high usage EVs.

Staples said the annual maintenance cost of a diesel delivery truck is about $2,700 in most years, including oil, transmission fluid, filters and belts. For an electric truck—which has no transmission and needs no fluids, filters or belts—the cost is about $250.

I can vouch for the advantage in brake wear from my own experience:

One big savings comes in brakes. Because electric trucks use "regenerative" braking, which returns some of the force of stopping to the batteries in the form of electricity, the brakes don't wear out as fast. That means the brakes last four or five years, not one or two, before they need a $1,100 repair.

Summary:

Add it all up and Staples expects to save nearly $60,000 over the 10-year life of an electric truck over a diesel model.

Stats on the Smith van:
range: 100 miles , 50 miles
top speed: 50 mph
payload: up to 8 tons
recharge time: 6-8 hours
cost for 50 mile version:$90k vs $60k diesel.

 

[BilPrestonEsq]

The solution to energy crisis has been discovered and I have already invested: the Snuggie (blanket with sleeves).


As for the problem with heating electric cars, how much propane would it take to keep an electric car at 70F for a 1-hour commute?

That is hilarious I am still laughing a little even now


I have done a lot of thinking on electric cars and I have never thought of heating or cooling the car. Wow

So my two cents in this discussion is this(keeping it short): I think that more giant power plants isn't the answer. A lot of smaller ones would be better. Everything is going to have to become more locally based( well maybe we should keep trying to figure out the whole fusion thing). I just like the idea of having my own personal power supply, same goes for food supplies but that's a different topic I guess, well except for all the energy we would save if we didnt have to drive all our food across thte country and ship it in from other countries. Also home design is HUGE and the materials that go into them. How many houses are designed for passive solar heating? Not many. Passive Solar design in itself would save such a massive amount of energy and that's just the tip of the iceberg. And for cars, well if we worked closer to home we wouldn't have to drive as much. I do think that we should be driving electric cars, the ones with hub motors that burn biodiesel in super efficient free piston linear generator motors that take advantage of regenerative braking and regenerative shocks(I know that was talked about already). Well I don't want to type anymore but those are a couple of things that I could elaborate on if this discussion is continued mainly home and building design there is so much to talk about though.

 

[Topher925]

I recently attended a green car expo this past weekend and had the chance to talk to a (very cute) GM rep who was showcasing the chevy volt. She informed me that the latest and greatest batteries from CPI was providing an estimated battery life of about 150k miles, much greater than the current estimated battery life.

Apparently GM is still working with A123 as well and they may become their future supplier. GM has also developed a fuel cell version of the volt, although they don't showcase it nearly as much as the new equinox.

 

[brainstorm]

So my two cents in this discussion is this(keeping it short): I think that more giant power plants isn't the answer. A lot of smaller ones would be better.

Strangely, I have never seen comparative analyses between different configurations of generators and grid maintenance costs (including energy costs). You would expect that some efficiency is gained by the scale of a large central power plant and a widely dispersed grid, but maybe it is the opposite and sprawling urban/rural areas could better scrap their grid lines and recycle them into solar panels. The problem with solar is storage, even when you reduce your power usage to fall within the capacity of your solar system. In denser areas, the costs and materials for maintaining a grid and central generator are probably must less per unit consumption. Surely heating a multistory apartment building uses much less energy than if the same residences were spread out as numerous single-family dwellings?

I just like the idea of having my own personal power supply, same goes for food supplies but that's a different topic I guess, well except for all the energy we would save if we didnt have to drive all our food across thte country and ship it in from other countries.

I would be interested to know how much fuel is consumed by all food-related transportation. I'm not so sure that more fuel is used by ocean ships than trucks driving across land. It may also be the case that the shipping logistics of food-distribution is relatively well-planned and efficient and the biggest energy-waste is due to maintaining climate-controlled and otherwise luxurious supermarkets and prepared food distributors (e.g. restaurants). It could be that if vegetables were grown locally in warm months and more storable dry foods like rice, grains, etc. were distributed out of the backs of trucks, UN-style, that this would cut most of the fuel loss.

And for cars, well if we worked closer to home we wouldn't have to drive as much. I do think that we should be driving electric cars, the ones with hub motors that burn biodiesel in super efficient free piston linear generator motors that take advantage of regenerative braking and regenerative shocks(I know that was talked about already).

Driving less is the holy grail of fuel conservation. More efficient cars are a neat idea, but ultimately how much fuel can you save when you're moving around 2000+ pounds of vehicle weight in addition to passengers and cargo? Trains seem most efficient to me because they have practically no rolling friction and they are long, which would seem to minimize wind-resistance. Rails are expensive to maintain, though.

 

[Dr Lots-o'watts]

As for the problem with heating electric cars, how much propane would it take to keep an electric car at 70F for a 1-hour commute?

Why not just regular gas, but used exclusively for heating? Or traditional heating oil?

 

[mheslep]

I recently attended a green car expo this past weekend and had the chance to talk to a (very cute) GM rep who was showcasing the chevy volt. She informed me that the latest and greatest batteries from CPI was providing an estimated battery life of about 150k miles, much greater than the current estimated battery life.

Apparently GM is still working with A123 as well and they may become their future supplier. GM has also developed a fuel cell version of the volt, although they don't showcase it nearly as much as the new equinox.

1. Was that mileage life for the Volt battery (future), or some other, generic, LG CPI battery? 2. Did you get her ph number?

 

[Topher925]

1. Was that mileage life for the Volt battery (future), or some other, generic, LG CPI battery? 2. Did you get her ph number?

1. Yes, the vehicle life of the Volt. 2. No, I kept getting cock-blocked from people going up to her and asking stupid questions.

 

[PhilKravitz]

Issue as I see it is lack of energy independence.

My favored solution is what some call the Matt Simmons plan (see Ocean Energy Institute) which is
1) off shore wind powered electrical generators up and down both the west and east coast
2) on shore wind up and down the middle of the country
3) PV solar in the southwest
4) oil from algea in the southeast

I am also interested in Thorium based nuclear.

Where will the money come from to do this? I do not see a politically doable way to make this happen. If we could divert money from the two major federal expenses health and military to pay for this then we could do it. But that seems unlikely.