# Tesla’s batteries – past, present and future



## BelgiumEV (Aug 24, 2015)

Hi has any forum member an idea wether it is an option to try and make a conversion with Tesla type batteries? Or even with the actual Tesla batteries, I mean they said they were giving away their patents so perhaps that includes the patents on how they use these batteries in their cars?
It seems like a well researched option to use these small batteries and also quite handy to fit them in available space during a conversion, compared to the chunky big batteries...


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## Karter2 (Nov 17, 2011)

Not quite so simple..
Tesla packs are rare, expensive, and custom shaped to fit their cars, 
Reusing one generally means dismantling it and reconfiguring the many 1000's of cells into a useable pack size, shape , voltage, and capacity, to suit your particular vehicle. .. a lot of work and connections to make.
but people have done it and there are videos of how to dismantle the packs.
I would suggest it is not a task to be underestimated !


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## AntronX (Feb 23, 2009)

I don't see a reason to cut up tesla model s battery modules. They are about 4.8KWh each and 22V. You could wire 6 or 7 of them in series and use DC motor or HPEVS kit.


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## Karter2 (Nov 17, 2011)

there are many ways you could reuse the Tesla pack /modules, and that is certainly one of them.
But the OP was suggesting the ability to use pack modules smaller than the usual LiFePO4 bricks would be an advantage.
A 4.8kWhr, 23 kg , Tesla module is not the most friendly size !


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## BelgiumEV (Aug 24, 2015)

thanks for your answers! I see the issues now Karter2, will try to find the videos you refer to. Wouldn't it be great if Tesla would sell their batteries and engines seperate to DIY'ers (in different shapes and sizes...)?


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## Hollie Maea (Dec 9, 2009)

BelgiumEV said:


> Wouldn't it be great if Tesla would sell their batteries ... to DIY'ers


There have been a whole host of people (myself included) who have put up feelers about selling high quality engineered 18650 packs that would work well for DIYers. There's no market for it when you can buy a salvaged LEAF pack with the change you find in your couch cushions.


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## dougingraham (Jul 26, 2011)

BelgiumEV said:


> Hi has any forum member an idea wether it is an option to try and make a conversion with Tesla type batteries?


Of course it is an option. Jehu Garcia has been partially driving on a couple of modules he built from used 18650 laptop batteries. In his case he paralleled 150 cells to meet the peak demands of his 650 amp HPEVS AC-50 setup. This gives him around a 300 AH module. He has some YouTube videos of his project. You can get a large and inexpensive (in dollars) battery with this solution but extremely labor intensive. 



BelgiumEV said:


> Or even with the actual Tesla batteries, I mean they said they were giving away their patents so perhaps that includes the patents on how they use these batteries in their cars?


And Jehu has also played with using Tesla Modules in his experimentation.

As near as I can tell there isn't anything patent-able in Teslas modules. Everything in there could easily be found elsewhere. And just because the Patent Office issues a patent does not make it defensible.



BelgiumEV said:


> It seems like a well researched option to use these small batteries and also quite handy to fit them in available space during a conversion, compared to the chunky big batteries...


Not so much as you might think. To use the Tesla technique you have to parallel 74 cells in a flat plane which makes a somewhat bulky brick. You want all the paralleled cells at the same temperature so they need to be tied together physically and electrically so that all the paralleled cells share the load. A 100 AH prismatic with a 10C discharge potential may be 1/2 the wh/kg rating of the cells Tesla is using but the wh/liter rating is not nearly as good. This is because in a prismatic all the space inside the container is used while with a round cell with cooling tubing running between adjacent cells you only get active material in the cylindrical area of the square space the cells uses. An 18mm dia cell has an effective area of (18/2)^2 * pi = 254.5 sqmm. A square with sides of 18mm uses 324 sqmm. So the density is less than 79% of a prismatic.Once you get the cooling in there is is probably well below 75%. A Tesla module has 74 cells paralleled and those cells are about 3.2 AH making for a 237 AH equivalent cell. And although the wh/li numbers for a single cell are three times better than the best of the prismatics once you turn 74 of the into a module you end up at about twice as good. So 100 AH prismatics are about the same volume as your 237 ah Tesla configuration. Finding room in a typical conversion for that is a big problem. But if you can afford that large of a pack you get twice the density and half the weight for the same wh. (it is actually a little better than this because we are comparing cells with 3.7 volts to those with 3.2 volts).

And a lot of the discussion in this thread really belongs under the batteries section.


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## CadenceEV (Aug 27, 2015)

BelgiumEV said:


> Hi has any forum member an idea wether it is an option to try and make a conversion with Tesla type batteries? Or even with the actual Tesla batteries, I mean they said they were giving away their patents so perhaps that includes the patents on how they use these batteries in their cars?
> It seems like a well researched option to use these small batteries and also quite handy to fit them in available space during a conversion, compared to the chunky big batteries...


I have plans for a conversion with Tesla modules right now. I will let you know how it goes.

While their patents are informative and definitely fascinating, they are no instruction manuals. They give you very high level views of their technology, which could possibly inspire DIY solutions for us, but it would be difficult to use their tech as is.

With energy density (Wh/kg) at almost twice as much as your average Chinese LFP, it makes for a very attractive option once more modules get flooded into the used market and prices go down.


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## tomofreno (Mar 3, 2009)

Hollie Maea said:


> There have been a whole host of people (myself included) who have put up feelers about selling high quality engineered 18650 packs that would work well for DIYers. There's no market for it when you can buy a salvaged LEAF pack with the change you find in your couch cushions.


 Do you need a house cleaner?


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