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Building a Safer Lithium-ion Battery - Part 3

Concluding interview with Marc Kohler on Valence Technologies' lithium-ion batteries

By Josh Landess

Editor's Note: Due to length of interview we had to complete final half in two parts.

EVWorld: A big-picture topic of mine is efficiency…Energy Efficiency of Battery Electric Vehicles. I just got through talking to some of the Fuel Cell guys and I said: "Look, this is not impressive. Your percentage on your electrolysis and your percentage on your fuel cell add up to something like 35 percent (based on what I'm told). That's about a good internal combustion engine car."

What, approximately, would be your wall-socket-to-wheel efficiency?

MK: Right. I had that same conversation yesterday with a guy from Daimler-Chrysler. If you're going to use electricity to generate the hydrogen from electrolysis, [and] then pump [the hydrogen] into a tank....

EVWorld: ...even being generous and saying very high efficiency electrolysis...

MK: ...and you have all of these steps so that if you're already starting with electricity why wouldn't you just put it into battery pack on the car and run? I don't know. And we debated that a little while.

As far as socket-to-wheel efficiency, say your charger comes into play anywhere from like 85 to 90 percent efficient, and what rate and so forth, then you have your battery efficiency, which depending on chemistry can be – have any – probably anywhere from 80 percent to 95, 98 percent efficient. Then you have your controller efficiency and your motor efficiency and drive train.

EVWorld: What would be the high end for battery efficiency? 98 percent? MK: I would say 98 percent efficient. Now, if you were talking about watt hours efficiency it's a little different than amp hour efficiency Coulombic, but it's still very good. Maybe mid-90's for the watt hours.

{Note: we never did tally up the final figures on our estimate for wall-socket-to-wheel for a Saphion-powered-EV.} {the above percent's work out to 60-70 percent efficient}

Valence History:

EVWorld: Where does your company come from? You guys have been around as a stock symbol for me at least four or five years.

MK: We started in '89 in Silicon Valley area doing pretty much research for Lithium batteries. They've gone through lots of different routes, different chemistries – Cobalt, Manganese. I think around '96 or '97 they started investigating phosphate technology, looking at something safer than what's out there, and about two or three years ago a new management team was brought in to commercialize product. Instead of being focused -solely on research and development, keep doing that but also develop some products in which you have our N-Charge Laptop Battery Supplement, and now we're doing large format.

EVWorld: Getting back to the safety thing: This phosphate type battery - does anybody else do that?

MK: No. We have Patents, we have IP, on the materials and the process.

EVWorld: Does that isolate you too much to be involved in the auto industry? Do they not like the idea of one company having a key [technology]?

MK: I don't think so. We've done a program with USABC on a technology assessment proposal, and we've just submitted another one to develop packs for hybrid electric vehicles.

EVWorld: I'm trying to find out what the catch is. Every battery person I talk to, sometimes I come away saying "Oh I didn't ask the one question… What's the one weakness…?" I guess I can't see the problem if the fast charging works out, if all these other things fall into place.... It does sound a little expensive, but prohibitively so? I don't know.

MK: Right, and we're working on that. And it depends on the application, depends on the format. What I mean by that is: The application determines what is 'prohibitively expensive'.

For instance a lot of people come up and say "What do you cost?... Oh, that's six times lead acid." Yes it is, but lead acid doesn't give you this energy, doesn't give you this weight, cycle life. There's lots of other things…

EVWorld: Cycle Life. What did you say: 2000 times?

MK: 2000 cycles, yes. People are just looking at up-front-cost rather than what it can do for you. Will it lighten your vehicle? With an electric bike or a moped or something like that, weight is very crucial.

EVWorld: What type of warranty do you have?

MK: It kind of depends on the application. Traditionally you have a one-year warranty. We can, depending on the customer and the arrangement, do a three year warranty pro rate. We can work with the customer and the environment to give the necessary assurance that the battery is going to last as long as we say.

Times Article Viewed: 7216
Published: 10-Jan-2004

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