Justification for 300 mile battery

[Robert.Boston]

gg's list

That's a very good list, GG. The extra $10k could also be invested towards the replacement battery; if technology moves along as quickly as we hope, that $10k will be able to buy a 400-mile+ battery in five years. Would you rather have 230 for 5 years and 400 thereafter, or 320 for the stretch? (Both options costing the same.)

 

[richkae]

To play the devil's advocate here, here are my (probably misguided or misinformed) reasons to settle for the 230 or maybe, even the 160 (given my daily commute of < 60 and longest weekend road trips of ~100):

1) 300 has newer chemistry (does it?) so, could, in theory, have more issues in the first year or two?!
2) Why make the car heavier than I need it to be? Wouldn't I effectively be "burning" more electricity per mile traveled in a heavier car?
3) The car price savings upfront could be invested elsewhere in a prudent/safe manner towards a new Tesla a few years later (or atleast towards a replacement battery pack) - if not towards my son's college fund :smile:
4) Larger carbon footprint in manufacturing and subsequently recycling (or disposing of) the larger number of cells in the 300 pack
5) Show EV naysayers - by living with the smaller battery pack for a long period of time without any issues - that range (that's not really required in a given situation such as mine) is not really everything
6) Be minimalistic - why consume more than I need?

1. Possible, but I believe each pack is using different new chemistries.
2. If #1 is true and each cell has more energy, then the weight may not be much different.
3. Agreed, except that the 300 mile pack will have a longer service life and not need replacement as soon.
4. The 300 mile pack will have a longer service life. The improved service life ratio may exceed the ratio of increased cost.
5. Show EV naysayers that you can make the same long trips as ICE cars.
6. No argument.

 

[Dan5]

Number for about a larger carbon footprint may not necessarily be true. Assuming the batteries are recycled, the cost of energy for manufacturing decreases by 90%.
All the batteries are lithium chemistries, but the reactions vary. You could go from a pretty nasty, caustic process to a more benign process. That was the basis of my research thesis. The only way to know for sure is to audit the battery makers for their processes for making the batteries (not going to happen). As an example, refining colbalt is alot more energy intensive then using recycled iron and phosphoric acid.

 

[Trnsl8r]

A charge cycle is from 0% to 100%. This is called deep cycling. From the battery spec sheets from Panasonic, it looks like it retains between 60-70% after around 500 deep cycle charges. This is very abusive to the battery though- more like a worse case scenario. To put in perspective, it's like running to empty then over filling in an ICE car (you damage the fuel pump and system if you do that on a continuous basis). To prolong the battery life, it's recommended to use a 220 or 120 and slowly charge it and keep the car within the 10% to 90% range (mid 80% capacity of the battery). That really prolongs the life of batteries
In terms of battery chemistry, it's ok to use the 480V fast charge occasionally, but it's not recommended to do it on a regular basis (faster charging means more heat generation in the cells when charging) and there is a slight risk of "cooking" (degrading) for some cells. (the lithium colbalt oxide family batteries have this issue).
If you are going 150-200 miles you should have no problem, with the 30 miles, I would charge it once a week or something.

OK, sorry about going off-topic here but now I'm curious. You're talking about the battery as a whole, right? Now from what I read, the battery consists of thousands of pocketlamp size batteries all connected together. What is the charge cycle for those individually? Do they get pumped to 100% and then drained or are they also used more "carefully" and charged to 80% and then stopped draining at 20% unless range mode is on?

 

[Robert.Boston]

My understanding is that the cells are balanced; ideally, each cell will have the same state-of-charge (SOC) as the others. BTW, normal charging runs up to 90% and down to 10% (using 80% of the battery's capability) as Dan5 noted, not up to 80% and down to 20% (using 60% of the potential) as you suggest.

 

[Trnsl8r]

My understanding is that the cells are balanced; ideally, each cell will have the same state-of-charge (SOC) as the others. BTW, normal charging runs up to 90% and down to 10% (using 80% of the battery's capability) as Dan5 noted, not up to 80% and down to 20% (using 60% of the potential) as you suggest.

Oh right, caught that after I posted. Sorry for playing a bit fast and loose with the numbers there, but you answered my question althesame. Thanks.

 

[stopcrazypp]

To play the devil's advocate here, here are my (probably misguided or misinformed) reasons to settle for the 230 or maybe, even the 160 (given my daily commute of < 60 and longest weekend road trips of ~100):

1) 300 has newer chemistry (does it?) so, could, in theory, have more issues in the first year or two?!
2) Why make the car heavier than I need it to be? Wouldn't I effectively be "burning" more electricity per mile traveled in a heavier car?
3) The car price savings upfront could be invested elsewhere in a prudent/safe manner towards a new Tesla a few years later (or atleast towards a replacement battery pack) - if not towards my son's college fund :smile:
4) Larger carbon footprint in manufacturing and subsequently recycling (or disposing of) the larger number of cells in the 300 pack
5) Show EV naysayers - by living with the smaller battery pack for a long period of time without any issues - that range (that's not really required in a given situation such as mine) is not really everything
6) Be minimalistic - why consume more than I need?

1) 300 uses Panasonic NCR18650A which is Panasonic's new NNP (Nickel Oxide Based New Platform) chemistry. However, it was already mass produced and sold since March 2010, and in general isn't much different from other standard 18650 cells (besides from capacity and some extra safety features). It still follows the same strict quality standards as other laptop cells, so I don't see why there should be any expectation that the defect rate would be noticeably higher.
http://www.engadget.com/2010/04/23/panasonics-3-1ah-batteries-to-be-used-in-the-tesla-model-s-hav/
http://industrial.panasonic.com/www-cgi/jvcr13pz.cgi?E+BA+3+ACA4001+NCR18650A+7+WW
2) The 300 pack will use the same amount of cells as the 230 pack. Each cell in the 300 pack only weighs a nearly insignificant amount more (45.5g vs 44g in standard cells, a 3.4% increase). The weight issue only applies if you are considering 160 vs 230, not 230 vs 300.
3) I agree you will get price savings that you can put towards other uses. I won't be too optimistic there will be new replacement packs for general sale after the warranty/7 year expect life is over (we'll have to see how Tesla handles the Roadster). Most likely it'll be refurbished packs, and even if they add new cells don't expect them to increase the energy density.
4) See point 2.
5) Leaf owners have been living with reduced range and Nissan showed survey results that say they are largely satisfied with it. Yet no one is convinced the general market will be satisfied with such range, and there's plenty that say Nissan's survey results are just from self selection.
6) Again, see point 2.

 

[EVNow]

If you drive 50 miles per day, the 160 cuts it close after 2 degradation cycles (300,000 miles), 230 after 3 cycles (450,000 miles), 300 mile after 4 degradation cycles

Unlike what a lot of people think, the degradation after 80% capacity loss isn't linear. It is exponential.

There are also shelf life issues with Li batteries.

I almost view 300 mile range vs 230 as I'd view hard drives. I'd not pay a premium to get the largest available HDD if I don't don't need it now. The prices fall and it would be much cheaper to buy it when I need it.

 

[ckessel]

I almost view 300 mile range vs 230 as I'd view hard drives. I'd not pay a premium to get the largest available HDD if I don't don't need it now. The prices fall and it would be much cheaper to buy it when I need it.

Battery capacity improvements vs. cost have not ever been and are not foreseen to be anywhere remotely close to the type of cost-to-capacity curve we've seen with hard drives. We might see articles like "Scientists discover 10x battery tech!", but even those that pan out won't be in production for a decade.

 

[EVNow]

Battery capacity improvements vs. cost have not ever been and are not foreseen to be anywhere remotely close to the type of cost-to-capacity curve we've seen with hard drives. We might see articles like "Scientists discover 10x battery tech!", but even those that pan out won't be in production for a decade.

Right - it won't be exactly like HDD. But - the basic idea still holds good. I expect doubling energy density and consequent halving of price per kWh every 5 years.

 

[ckessel]

I expect doubling energy density and consequent halving of price per kWh every 5 years.

Based on what data? What little I could find doesn't seem to support that assertion. For example: http://dukespace.lib.duke.edu/dspace/bitstream/handle/10161/1007/Li-Ion_Battery_costs_-_MP_Final.pdf?sequence=1

Costs will certainly come down, but it's a slow enough drop that it's not really relevant to any considerations about what battery to buy with the Model S today.

 

[EVNow]

Based on what data?

Amount of investment going into battery research. Historically it has been about 10% per year, which would get you to 60% of the cost in 5 years.

 

[ckessel]

Amount of investment going into battery research. Historically it has been about 10% per year, which would get you to 60% of the cost in 5 years.

Can you point to any sources? I can't find anything via Google to back that up and the source I linked doesn't seem to either. I've heard 8% before, but again, I can't find any supporting documentation.

Also, is that 10% capacity improvements or 10% cost reduction? They're not the same. It'd take 100% increase in capacity per $ to get a 50% effective cost reduction.

 

[Norbert]

Based on what data? What little I could find doesn't seem to support that assertion. For example: http://dukespace.lib.duke.edu/dspace/bitstream/handle/10161/1007/Li-Ion_Battery_costs_-_MP_Final.pdf?sequence=1

Costs will certainly come down, but it's a slow enough drop that it's not really relevant to any considerations about what battery to buy with the Model S today.

8% percent is what Tesla used to say in recent years, though I'm not sure whether that referred to cost reduction specifically, or improvements in general.

8% precent means 2.15x in 10 years. The report you mention ends at 2005, and in the time 1995-2005 it actually shows an improvement of more than 4x. However, according to that data, as the report points out, the price decrease diminished to 5.4% between 2002 and 2005. However, the graph appears to show a plateau between 2001 and 2002 (about 0%), and from then on (within the range 2002-2005) the decrease appears to have grown again. I'd guess that at least in the last few years, research has noticeably increased and will result in larger rates.

 

[ckessel]

The report you mention ends at 2005, and in the time 1995-2005 it actually shows an improvement of more than 4x.

Not exactly, I think you're were looking at the graph that showed Watt hours per Kilogram decreasing 4x, not the prices. The bit about prices is as follows from the article, which seems to indicate that we've already gotten the big gains in price and weight with Lithium Ion, so anticipating the large gains EVNow mentioned is unlikely. It'll be consistent refinement.

The compound annual price decrease for the period 1998 – 2005 is 9.9%, while for the period 2002 – 2005 itis only 5.4%. The decline in Li-ion battery prices is dueprimarily to rapidly increased production volume in Asia, as well as increased packaging efficiencies through better space utilization at the cell-level (Beach, 2008). Based on this decelerating trend of declining prices, a baseline scenario was chosen that assumes a 4% per year decrease in the overall cost for automotive Li-ion batteries.

The article goes on to indicate the most likely long term is 50% cost decreases after about 15 years (see Figure 12).

 

[stopcrazypp]

Not exactly, I think you're were looking at the graph that showed Watt hours per Kilogram decreasing 4x, not the prices. The bit about prices is as follows from the article, which seems to indicate that we've already gotten the big gains in price and weight with Lithium Ion, so anticipating the large gains EVNow mentioned is unlikely. It'll be consistent refinement.


The article goes on to indicate the most likely long term is 50% cost decreases after about 15 years (see Figure 12).

The most recent data I have found is the 2008 presentation by CTO Straubel:
http://www.whitehouse.gov/files/documents/ostp/PCAST/PCAST Sep. 2008 Straubel slides.pdf
Slide 3 shows cell pricing has stuck to around $2-3 since about 2006.

Slide 15 says ~5% per year improvement in density, and given cell prices stay about the same, that translates directly to ~5% lower costs/Wh per year.

Energy Density continues to improve (~5% / yr)

1.5-2X the energy storage capacity is widely predicted in approx 10 years
– 300 mile pure EV range possible
– 50 mile PHEV range possible with smaller and cheaper battery pack

Storage density increases drive down cost/Wh stored since Mfg cost/cell generally does not increase as much

Cycle and Calendar life are improving

Cell abuse tolerance continues to improve although this is in tension with energy density increases

However, recently Tesla has been saying 8% per year improvement to the press. I've verified that claim back in 2009:

Panasonic Develops High-Capacity Lithium-Ion Battery Cells that can Power Laptops and Electric Vehicles - Earth Times

New 3.4ah (mass produced 2012) and 4.0ah (mass produced 2013) 18650 cells in development by Panasonic. This answers my call for a ~2x improvement of density (which would roughly halve the weight of the current pack in the Roadster or double the energy for the same weight).

It seems the improvement estimate of 8% a year is fairly accurate. Starting with a 2.9ah baseline for 2009.

Year Actual Projected(8%/yr)
2009 2.9ah 2.9ah
2010 3.1ah 3.132ah
2012 3.4ah 3.653ah
2013 4.0ah 3.945ah

Hopefully, we see the same thing happen for automotive grade and other large format cells.

Although to be fair, 18650 battery density may have stagnated from ~2006-2009. Shortly after my post, there was an 2007 article posted that mentioned a 2.9ah Matsushita (parent of Panasonic) cell that went into limited production in April 2006 and mass production in 2007 and the announcement they were developing a 3.6ah cell.
http://www.dailytech.com/article.aspx?newsid=5681

 

[Norbert]

Not exactly, I think you're were looking at the graph that showed Watt hours per Kilogram decreasing 4x, not the prices. The bit about prices is as follows from the article, which seems to indicate that we've already gotten the big gains in price and weight with Lithium Ion, so anticipating the large gains EVNow mentioned is unlikely. It'll be consistent refinement.

Wh/kg is certainly increasing over time, not decreasing. I was looking at Figure 11. Price is the red curve with squares, in US$/Wh. It's been decreasing, in the last decade which the graph shows, 1995-2005, from about 1.7 $/Wh (above the 1.60 line), to about 0.3 $/Wh, 3 quarters to the 0.40 line (measured pixels). That's actually a factor of 5.7x, which is an average annual improvement, in price, of about 19%.

The article goes on to indicate the most likely long term is 50% cost decreases after about 15 years (see Figure 12).

I'm not sure this article (a masters project) is aware of all the research being done (that would be difficult for anyone), one constantly hears about significant improvements possible even within LiIon.

 

[Norbert]

The most recent data I have found is the 2008 presentation by CTO Straubel:
http://www.whitehouse.gov/files/documents/ostp/PCAST/PCAST Sep. 2008 Straubel slides.pdf
Slide 3 shows cell pricing has stuck to around $2-3 since about 2006.

The graph only goes until 2007 and a bit, so that's a plateau of a just bit more than a year. There have been plateaus before, so that doesn't necessarily mean it is stuck there.

The year just before, Jan-2005 to Jan-2006, showed an improvement, in price per cell, of about 18%, I measured the pixels.

(18% improvement = 15% reduction)

 

[ckessel]

1995-2005, from about 1.7 $/Wh (above the 1.60 line), to about 0.35 $/Wh, 3 quarters to the 0.40 line. That's actually a factor of 4.8x, which is an average annual improvement, in price, of about 17%.

That's kind of cherry picking the data from the graph to start with the 1995 year that has a massive 3 year drop. If you take the period of 1998-2005, the numbers look far less rosy. Plus the article seems to indicate the price drops were more due to ramp ups in production volume than tech breakthroughs. It's not really clear if even more volume is going to make much of an impact. The flatness of the graph post-1998 would seem to indicate it doesn't.

The steady improvements are great and bode well, but I just don't think EVNow's expectation is going to hold for battery pricing/performance following anything like Moore's law for computers. I'm very hopeful that if I buy a new car in 10 years, it'll be a marked difference, but I don't see anything that would warrant expecting to upgrade the Model S to a battery significantly bigger and cheaper 3-5 years from now.

 

[Norbert]

That's kind of cherry picking the data from the graph to start with the 1995 year that has a massive 3 year drop. If you take the period of 1998-2005, the numbers look far less rosy.

First, I corrected my numbers: it actually goes down to 0.3, not 0.35, which is even better. So the percentage improvement, in the last decade, is 19%.

I already mentioned in the message preceding the one you are quoting now, that "the price decrease diminished to 5.4% between 2002 and 2005". That's even less than the 10% between 1998-2005 which you are mentioning. (However it is increasing again since 2002, as seen in the graph stopcrazypp posted (which is in price per cell), up to 18% in 2005, but then again 0% in 2006).

So to talk about cherry-picking is rubbish, if I may say so. I chose the last decade simply because one usually gives these numbers for decades, and one does so since there are a lot of annual fluctuations. If I include 1991 (4 more years, the complete graph), the number is about 18% improvement (18% improvement = 15% reduction), going down again.

I'm very hopeful that if I buy a new car in 10 years, it'll be a marked difference, but I don't see anything that would warrant expecting to upgrade the Model S to a battery significantly bigger and cheaper 3-5 years from now.

I'm not that sure about 3-5 years either, but did hear something about a Tesla employee indicating that Bluestar batteries (that's probably 2015/2016) will be an improvement in price. Which they kind of need to be...