GNHBus,
You question is kind of like "How big of a gas tank do you need for a 300hp engine?" The answer is "it depends".
As discussed below, a Kokam battery bank as small as 1200Wh (48V x 25Ah) would support a brief burst of 12kW. A bank as small as 2400Wh would support that load until it was empty, probably less than 10 minutes. But all of this is simple math using the information that I already posted before.
So there is no real answer to your question.
Eric
--- In electricboats@yahoogroups.com, GNHBus@... wrote:
>
>
> What is the approx. investment cost of these Kokam Batteries for a 12kw electric marine motor?
>
>
> -----Original Message-----
> From: Eric <ewdysar@...>
> To: electricboats@yahoogroups.com
> Sent: Thu, Feb 3, 2011 6:33 pm
> Subject: [Electric Boats] Re: Government incentives?
>
>
> GNHBus,
>
> Kokam batteries are a unique format Lithium-Ion cells that are made with advanced nickel metal cobalt technology. You can find whatever info that is public domain on the internet. BTW, I believe that Kokam cells are actually manufactured in Korea, but I could be mistaken. Here's the link to the place in Pasadena where I was able to see them in action.
>
> http://dowkokam.com/index.htm
>
> These batteries are better suited for high amp load use cases like drag races and short course auto racing. Able to sustain discharge rates up to 10C for short bursts, they are rated for 5C discharge. In case you're not familiar with the terminology, in batteries 1C = Ah rating. So for a group 31 FLA battery (105Ah), 1C is 105A. Most deep cycle lead-acid batteries will support up to about 1.5C discharge rate. LiFePO4 prismatic cells (like my Thundersky cells) are rated for 3C loads, although I hope to keep things under a 1C rate. The guys I know with Kokams are finding ways to deliver more than 1000A to their motors, but there are problems beyond the batteries at those rates, i.e. smoked motors, controller, cabling, etc.
>
> I don't know of any of these end-user pioneers that are looking to the government to support their hobby, but they are getting a good deal of sponsorship from the manufacturers. Their kind of destructive testing is crucial to finding out what abuse the components can take in practical applications. I do know that our government provides considerable subsidies for many green technologies like the new tech battery manufacturers. As consumers, this shows up as the reduced prices that we pay for these batteries, still very high but much less than R&D prices. Until these technologies mature a bit farther, it's not realistic to expect the government to chip in again towards the end-user too. Remember, for each of these successful technologies, there were a dozen more that just didn't pan out. I'm glad that the government didn't sink too much money into supporting those ideas, because they weren't viable in the long run. This is an area where private investers like ventur e capitalists shine. They take the risk and sometimes reap the reward. I don't want the government being that speculative with my tax dollars.
>
> Fair winds,
> Eric
>
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