John Petersen's  Instablog

A reader named Doug Korthof just posted a comment to my August 2008 article "Battery Technology: A Different Set of Rules." While I've  always said that the comments are usually more interesting than my articles, Doug's recent contribution is the most lucid, accurate and complete comment I've ever received. Doug is an EV afficianado of the highest order and has been writing on EV issues for years through his website at www.EV1.org. So these are not the words of a wannabe or a techie, the're the words of somebody that I would classify as a real life EV expert who has learned the issues from real life experience rather than studies.

Doug's comment said:

"Energy storage is a technical topic too deep for most of those who comment on it. Mr. Petersen is a clear thinking non-techie who uses common sense, and qualifies statements about which he's not sure.

The other posters and commentators should pay heed, and not say silly things that make them look dumb. As the Chinese adage goes, "...'tis better to remain silent and be thought the fool, then open one's mouth and remove all doubt...".

There's a big difference in lead-acid batteries; most SLI (commodity batteries that are in a gas IC car) are designed to last little more than 3 years; yet it's possible to make a lead battery that lasts 100 years if only used for "Starting Lights and Ignition".

Energy storage using batteries, unlike SLI apps, takes "deep cycling"; if you use the battery in an EV, it needs also to put out a lot of power (up to 400 Amps -- and if you don't know what that means, you need to study before commenting). High power draw tends to break up battery insides, destroying the electrodes or other components, especially because mostly we hook them up in series to get high voltages. Other concepts you need to know are "internal resistence", "voltage drop", and "discharge curve". A123, for example, has an extremely flat discharge curve which makes it difficult to predict when the voltage drops to dangerous levels. This is part of the reason why GM chose to *buy* 16 kWh of Lithium (from LG, not A123) but only *access* 8 kWh, making it twice as expensive. NiMH and lead don't have that problem; you can run them close to "zero", we have many times, even below "zero".

Lithium gets torn up worse than others, in high power applications; lead acid actually does better, which we've found in actual experience using EVs. For backup power applications such as peak-shaving, this doesn't matter much; but it is a big deal for EVs.

Tesla, following ACP, uses commodity laptop 18-650 Lithium batteries in a parallel-series arrangement that allows monitoring in parallel and discharge in series; various newer Li chemistries have their own chemistries, and their own unsubstatiated (so far!) claims.

Now the other concept lurking behind Mr. Petersen's articles is that of "Life Cycle Costing" (LCC). Some uneducated or naive folks don't distinguish between "safe disposal" and "sale for junk value". Unbeknownst to the public, there's a whole industry involved in junk metals, what is now called "recycling". This has vast implications for LCC comparisons for the three technologies, and also for the issue of "material supply". If your lead is "mined" from junk batteries, you may never need to refine much new lead.

Lead acid batteries are almost all recycled; there will never be a shortage of lead at current prices because it's almost all reused and most of our lead supply comes from melted junk lead. "Dissipatory" applications, such as the former use of lead in paint or tetraethyl lead, where it can't be recycled, are no longer extant.

NiMH uses Nickel metal and some rare metals such as Vanadium, Titanium, and rare-earth misch metals. An industry can be made in reusing old Nickel batteries; most Ni comes from junk metal anyway, and most is used in Stainless Steel, Monel propellor shafts, surgical and corrosive environments, etc.

Lithium almost all comes from virgin Lithium, not because of the high temperatures, but because of the chemical properties of Lithium, which, like Na and K, reacts violently with water or humid air. Refining Lithium from ore does require processing of Lithium Carbonate, a stable form, but to purify the metal requires special attention to the explosion and fire danger. Hence, Lithium currently has no junk value; it's true that Toxco does recycle it, but I suspect mostly for the additives, Cd and Co; pure Lithium batteries have no junk value, they are "safely discarded into the trash" unless they have toxic Cd or Co.

Now LCC is composed of three elements:
Initial cost;
Logistic (support) cost;
Sunset (disposal) cost or credit.

With an article such as batteries, we amortize the LCC over the number of years or product cycles to compare the three.

Lead: low initial cost, low support cost, high junk value; 50K miles
Nickel: modest initial, low support, high junk; 200K miles
Lithium: very high initial cost, high support, no junk value; 50K miles.

Obviously, if you do the numbers, Lithium is (so far) way off the scale, much too expensive for EV application. Now you can argue about the numbers, but they are best we can do and from actual real-world applications. There are other factors: Lithium lasts longer in small cars, where it doesn't have to push so much weight, and all three have unique temperature and BMS requirements.

Lead: Less than $6000 over 50K miles for 12 cents per mile;
NiMH: No more than $11,000 over 200K miles for 5.5 cents per mile;
Li: Total cost of about $25,000 over 50K miles for 50 cents per mile.

Now this doesn't mean that Lithium is impossible; just that so far, it's not economical. In all the hype about Lithium cars, there is

NO LITHIUM EV WHICH HAS GONE MORE THAN 50,000 MILES WITHOUT SIGNIFICANT BATTERY DEGRADATION.

If you know of an EV that did so, I want to hear from you: call me at 562-430-2495. But so far, no car.

This irreduceable fact must be dealt with: but it takes some thinking to understand that Lithium might work well in a low-power-draw applicaton such as a cell phone or laptop, but not be as economical in a high-power-draw application such as an EV. Actually, in a cell phone, we use Lithium because of its sterling Wh/kg ratio, because it's the only one that meets the usage parameters, the cost doesn't matter.

Now as for peak-shaving, the advantage goes to Lead!!!

No one would think of using anything else for battery backup or storage, just looking at the LCC. For example, I have 7 year old $1500 total-cost top-of-the-line lead batteries for my battery backup, holding 13 kWh and still function at top rank. The same thing in Lithium might last as long (maybe not; there's a shelf-life issue with Lithium) but the cost would be outrageous, about 10 times the best lead-acid battery made."