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Forum » Other Forums » Electric Sports Cars

Battery type used in Tesla Roadster?

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Written on: 15 May 2008 [19:05]
pluginfuture Topic creator registered since: 12.02.2008 Posts: 7	Folks, I am wondering what kind of batteries the Roadster uses...Does anyone has an idea? I believe its a Lithium type but I would be interested in more details. The website gives out only limited info...Thanks
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Written on: 31 May 2008 [01:17]
jstack6 registered since: 27.10.2007 Posts: 29	They use about 6,000 of the 721 lithium ion laptop battereis. This is very similar to the ACPropulsion design use on the T-zero and eBox. It seems to be good in some ways but not in others. Imagine if you have one battery go bad that block shuts down, you get the pack checked and just replace one $5 battery. This beat 1 string of large battereis where if one goes bad your out of service and can't move. There is also a BMS Battery management system that checks heat and load to make sure all strings are in the safe operating range. It can open any strings with a problem and let you keep going with a little less range until you get it checked. On the bad side that's a lot of connections and extra work to build the racks and wire the series and parallel circuits.
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Written on: 31 May 2008 [15:49]
Lensman registered since: 31.05.2008 Posts: 75	Actually, according to Tesla Motors, the battery pack is designed to accommodate the failure of a few batteries over the expected lifetime of the battery pack. They claim that failure of any individual battery will be limited to just that battery, and that it won't cause an entire group to fail. Failed individual batteries won't be replaced. A few failures are factored in as part of the expected degradation of the battery pack over time. These batteries are only rated for lasting five years. That means in five years the battery pack will be degraded to only 80% of its original capacity. Obviously someone could keep driving the car past that point, if he's willing to accept somewhat reduced range and acceleration. But as I understand it, Tesla Motors' position is the battery pack should be replaced after five years.
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Written on: 01 June 2008 [16:04]
ecoadmin Administrator registered since: 20.07.2007 Posts: 504	Thanks Lensman for that informative post. And welcome to the forums. I hope you enjoy your time here. If they manage it the way you describe it, I see a fairly trouble free operation of the battery pack. If the packs still deliver 80% of their original capacity, I would say thats pretty good as this loss is managable. But to come back to the original question: Does someone know what type of cells are used to power the Roadster? LiFePo4, Lithium-Mangan or other cells? ecocarforum.com - Green Car Network
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Written on: 03 June 2008 [09:06]
Lensman registered since: 31.05.2008 Posts: 75	ecoadmin wrote: Thanks Lensman for that informative post. And welcome to the forums. I hope you enjoy your time here. Thank you! I know very little about lithium-ion batteries, and I can't seem to find anything definitive at the Tesla Motors Club forum, but following links from Wikipedia's "Tesla Roadster" article I find: ~~~~~~~~~~~~~ # Cell type: lithium ion, 18650 form-factor (18mm diameter by 65 mm length). Most laptop computer batteries already use this type of lithium-ion cell. # Cell count: 6,831 cells arranged into 11 modules connected in series; each module contains 9 "bricks" connected in series; each "brick" contains 69 cells connected in parallel (11S 9S 69P). ~~~~~~~~~~~~~ http://www.celebritygenius.com/Jeff-Skoll/biography.html?title=Tesla_Roadster For those who want more info, there are four references regarding this paragraph, footnoted in the article. The designation 18650 apparently refers only to the physical structure of the cell, not the chemistry: "By far the most economical lithium-based battery is the cylindrical 18650 cell." Quoted from: http://www.buchmann.ca/Article6-Page1.asp Note the quote above, "each 'brick' contains 69 cells connected in parallel", confirms that the failure of any individual battery won't result in the failure of an entire group or "string" of cells, as would happen if the individual cells were connected in series. In fact, since they're connected in parallel, I don't think it's correct to describe them as being in "strings". If the question was about who the manufacturer is, apparently Tesla Motors will be using more than one source. Tesla's own article on its battery pack says in part: ~~~~~~~~~~~~~ The engineers at Tesla Motors selected cells from reputable Fortune 500 battery suppliers that have each produced billions of safe, reliable, Li-ion batteries. All the cell manufacturers that Tesla Motors has considered invest a great deal of money and engineering resources to minimize manufacturing defects within their cells. Overall, the selection criteria used by Tesla Motors included multiple factors, confirmed by extensive internal and external testing, that directly relate to the cell’s overall safety in the Tesla Roadster. ~~~~~~~~~~~~~ http://www.teslamotors.com/display_data/TeslaRoadsterBatterySystem.pdf [This article was edited 3 times, at last 03.06.2008 at 10:26.]
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Written on: 15 June 2008 [16:49]
ecoadmin Administrator registered since: 20.07.2007 Posts: 504	Thanks for the research Lensman. After some more hours of reserach I've come across a discussion about the Roadster batteries in an Aptera forum. TM uses indeed laptop-type batteries of LiCoO2+graphite type. They have a high energy density at low weight, but cannot be charged as fast as other Li-Ion types. While they might be ideal for the Roadster they might not be the right choice for a commuter EV. ecocarforum.com - Green Car Network
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Written on: 16 June 2008 [19:21]
Lensman registered since: 31.05.2008 Posts: 75	As with most real-world applications, there must be tradeoffs and compromises. For laptop-type batteries used to power an electric car, there must be a tradeoff between weight, efficiency, price, and safety. The fact that a few fires have been started by li-ion laptop batteries is a major safety concern for Tesla Motors, and is something any auto manufacturer using similar batteries will have to deal with. As I recall, Miles Automotive Group claims its future XS500, an all-electric sedan, will use different battery chemistry which isn't a fire hazard, which will allow them to build a battery pack without the thermal monitoring and cooling equipment in the Tesla battery pack. Of course, I have no idea how true or false this claim will turn out to be. But I wish them luck!
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Written on: 12 July 2008 [19:49]
Lensman registered since: 31.05.2008 Posts: 75	An article about how the Tesla Roadster's battery pack will be recycled and eventually disposed of: http://tinyurl.com/2ucqmr I had assumed the claim it's "entirely non-toxic" and was "safe to put in a landfill" was an exaggeration, PR spin to help sell the car to environmentally- conscious customers. But apparently it's true.
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