Battery talk

<div class='quotetop'>QUOTE(etyler88 @ Jan 12 2007, 04:01 PM) [snapback]374841[/snapback]</div>

Then how can one explain the DIY plug in hybrids. What do they know that industry doesn't know.

 

<div class='quotetop'>QUOTE(burritos @ Jan 12 2007, 05:59 PM) [snapback]374898[/snapback]</div>

Or what acpropulsion have done just with a Scion xB: http://www.acpropulsion.com/ebox/specifications.htm

With a range of 140 - 180 miles, why that's only going to meet the needs of 95% of Americans daily driving...

 

<div class='quotetop'>QUOTE(etyler88 @ Jan 12 2007, 03:01 PM) [snapback]374841[/snapback]</div>

Interesting comparison between battery technology and colonization of the Moon; I wonder where the money would be spent for a better purpose (with apologies to those responsible for the technological wonders derived from the space program.) Quit giving us excuses and get on with it!

 

<div class='quotetop'>QUOTE(burritos @ Jan 12 2007, 05:59 PM) [snapback]374898[/snapback]</div>

I think the issue here is battery life. For example, CalCars put out plans for a DIY PHEV Prius conversion using sealed lead-acid batteries, with an expected working life of maybe 800 cycles -- like a year or two of use. Other DIY, I'm not sure.

I've been tracking the commercial Prius PHEV modifications that have been anounced, so I've been looking into this a fair bit. Here's what I think is the most telling item: Of the three commercial PHEV Prius conversions that have been announced for the US, two offer no guarantee whatsoever on the battery, one (Hymotion) offers two years. And if you look back to the battery manufacturer website, for the Hymotion conversion, it's not so clear whether or not you should expect it to last vastly longer than that. They talk about useful Li-ion battery life on the order of 1000 -2000 discharges, which at the low end would be three years, one discharge a day.

The other thing that seldom gets mentionied is that Li-ion batteries simply break down over time -- they just plain age, regardless of use, again on a timescale of a few years. I have yet to see anyone flat out claim that their Li-ion battery does not age. One manufacturer (Altairnano) claims vastly more cycles (on the order of 15,000), but as was pointed out in a recent thread, Altairnano was kind of vague about the aging issue and about battery life in years rather than discharge cycles. So, even if you use it lightly, the expected lifetime of a traditional Li-Ion battery is limited. My understanding is that the most recent gen of Li-ion batteries is showing much longer "shelf life" if you will, but I have not seen anybody say that they've solved the aging issue for a Li-ion battery in a way that would allow the original battery to last the expected lifetime of the car. (If anybody knows differently, please correct me on that.)

So, on the aging issue, it's gettting better but it hasn't been proven to be solved, that's my take on it.

Clearly some batteries will last a long time as EV batteries -- the RAV4 EVs are proof of that. My understanding is that the PHEV battery packs get much harder use than EV battery packs, and that's what makes the difference. You seldom take the EV right down to full discharge, but with a PHEV pack, that is the expected normal mode of operation. The whole point is that the tyipcal user will charge them full up and drain them completely empty every day. Under those conditions, I don't think the NIHM batteries that they used in the RAV4 would last the life of the vehicle. Ditto for the current Prius battery -- it'd be dead in a couple of years if you ran it from full to dead every day.

Anyway, that's my take on it.
1) Yes you can make a PHEV Prius.
2) It'll kill any existing battery in a few years, if you charge it full and drain it dead every day - which is how PHEVs are supposed to be used for maximum benefit. As far as I know nobody has a battery that will last th life of the car under those conditions (and if anybody knows of one, please speak up.)
3) The reason that doesn't happen in EVs (e.g., the RAV4 EV) is that EV's typically dont' run through the full charge to complete discharge cycle every day. They rarely do in typical use.
4) All lithium ion batteries age, regardless of use, due to their internal chemistry. That issue is getting better with the most recent geration but I don't think it's been solved, in the sense of having a Li-ion batery that will last a car lifetime (e.g., 10 years) while sitting on a shelf, let alone while being used. (Again, if anyone knows an example to the contrary, please correct me on this.)


So when the car makers say we don't have a battery that will do, I believe them. I think what they mean is (take your pick) a) we don't have a battery we can guarantee for (e.g.) 8 years in the car, or B) we don't have a battery that's cheap enough to throw away every (e.g.) 3 years.

On the other hand, GM announced the Volt for 2010, Toyota talked off an on about a stock PHEV option in 2009, so somebody seems to think this is going to be solved in the near future. But as the quote said, I don't think there's any off-the-shelf solution to the battery life issue yet.

 

<div class='quotetop'>QUOTE(chogan @ Jan 13 2007, 09:37 AM) [snapback]375120[/snapback]</div>

Here is the battery that can last 10 years, 150k miles: http://www.greencarcongress.com/2006/03/nec_and_fuji_he.html

I think there is a solution already. I believe the only remaining challenge is to bring the price down. Remember, Toyota own 8.7% (largest share holder) of Fuji Heavy Industry. We don't know any detail of how the dissolve affects the Managense Li-ion battery. It is interesting how Toyota bought 8.7% of Fuji Heavy Industry right before this dissolve.

One possible outcome is that NEC Lamilion Energy could partner and supply these Manganese Li-ion battery to Toyota, the same way Panasonic EV is supplying Nimh HEV packs to Toyota.

Dennis

 

<div class='quotetop'>QUOTE(usbseawolf2000 @ Jan 13 2007, 11:33 AM) [snapback]375149[/snapback]</div>

Thank you. I stand corrected.

 

<div class='quotetop'>QUOTE(usbseawolf2000 @ Jan 13 2007, 11:33 AM) [snapback]375149[/snapback]</div>

Digging deeper, I found an article supporting my conjecture. This article contains many possible improvement technology in the next Prius. One that caught my eye is GTBT (grounded-trench metal-oxide-semiconductor-assisted bipolar-mode field effect transistor) which seems to be superior over IGBT. This power swich would greatly reduce the power drain while waiting for someone with the car powered on (say battery idling).

Toyota has been testing Li-ion battery (from PEVE) in a production car (Vitz) since 2003. Although it is not a full hybrid, it should give enough data for the life and durability to use in a full hybrid.

 

Morning all, interesting discussion...

I was actually just discussing the PHEV thing with my roommate earlier tonight (he watched the 'who killed the electric car' DVD I got him and was partially curious). He knows I've been following that trend, and we discussed a couple items (mainly the cost issue).

It's good to hear that there is a possible battery that can now do this, if the cost is brought down low enough. But there is another item that was brought up tonight - there is no long-term / real-world data on the battery tech.

I'm looking over the current warranty info for Prius (dealer had a second buyback offer, so I wrangled an '07 - finally with NAV! - out of them today), and the Hybrid System (presumably including the battery) is warranted to 96 months / 100,000 miles.

Kinda stopped my search for a PHEV conversion when I hear that the existing system is now guaranteed for 8 years - my original Corolla lasted just shy of 10, and that only because it became 'light duty' two years prior.

But, also, that's going to make Toyota really cautious about what higher-capacity batteries they may want to convert to. And rightly so - a mistake will be expensive and they'll take a big hit for it. Best guess would be for mid to late 2008; Either in time for halfway down the 2008 model lines or the beginning of the 2009s. It all depends on how far along the internal testing is going, and how the results are stacking up.

*wave*
--TSK

 

<div class='quotetop'>QUOTE(T_S_Kimball @ Jan 14 2007, 02:09 AM) [snapback]375431[/snapback]</div>

For states like CA, MA, ME, NY, and VT, those who adopted the CA new car emission standards, the hybrid battery and emission controls are warrantied for 15 years/150k miles.

http://www.arb.ca.gov/msprog/ccbg/atpzev.htm

 

I can think of another reason why making batteries for PHEV vs just pure EV's is harder. EV's typically have more cells arranged in parallel to get the increased capacity. This means the current draw on each cell is a lot lower resulting in lower operating temps, helping to extend the cell life.

Regarding calendar life, all the new cells (A123, Altair etc) are really too immature to truly know how they will hold up. Cycle life is easy to verify but not so with calendar life. I could see major car manufacturers wanting 3 - 5 years of experience with batteries before mass scale usage. Large scale failures would be very costly and damaging to the reputation of plug-ins.

 

I just read some interesting rumours....

Apparently, the A123 systems battery (safe, fireproof, long life, high power), which GM/cobasys are currently evaluating as a powerpack for the Volt is NOT as good as it could be!

Here is how the rumour goes.... ( I should reiterate that all of this is an informed RUMOUR so far! )

The question is all about who really invented the revolutionary A123 battery chemistry. Yes, it came from MIT labs, but apparently not directly.

The A123 chemistry was in fact developed by Dr. Donald Sadoway, currently the head of the MIT battery department. It has been claimed that this chemistry was removed from Dr. Donald Sadoway’s lab by an assistant who then went, on his own, to form A123 Systems to produce the technology. MIT quietly and successfully sued A123 Systems for licensing infringement, and the case vanished with a secret OUT OF COURT SETTLEMENT.

However more recently, Donald Sadoway himself was quoted in Forbes Magazine saying that his lab has “solid-state†Lithium Ion chemistry with DOUBLE THE DENSITY of the liquid based A123 Systems chemistry. Dr. Sadoway’s chemistry, which was presented at Yale last year is much more advanced than the chemistry currently in production by A123 Systems.

So it appears that the stolen A123 chemistry was only the half-way house, a stepping stone to the real breakthrough.

If the promised solid-state version has a similar safety profile, but with 200 Wh/kg energy density, then a 200 kg battery pack could store up to 40 kWh, enough for 200 miles EV range.

I'm looking forward to hearing more about this....

 

Well, the actual discovery was found by the MIT Professor Yet-Ming Chiang (one of A123 founder) and his coworkers.
http://www.sciencenews.org/articles/20020928/fob4.asp