# reconfiguring Tesla battery modules to 50v for TR4A project



## alex d (May 10, 2015)

I have battery modules from a p85 Tesla. these are configured 6s74p producing 24.9v at 100% soc. I am only going to use 8 of the 16 modules as they weigh almost 26 kg each and I don't want to overload my Triumph TR4a (see my ev album profile). this will mean I have a 43kwh capacity which will give me a great range and keep the car at a stock weight as the total pack will be around 200kg, the only problem is that 8 modules will only provide 200v and my Siemens/ scottdrive 200 set-up ideally wants around 400v.

I have been thinking of ways to reconfigure each module from 6s74p to 12s37p. I was thinking about removing the aluminium plates that connect the cells together and taking the cells out to reorientate them appropriately and then laser cut some new redesigned plates to each side of the pack but this would take too long and I didn't want to destroy the pack as its held together with some pretty strong glue.

instead I have bought a router attachment for my dremel and I am going to cut the metal plates in half, whilst connected to the module. I am making sure not to cut the pre made links in the pack between the cells + and - terminals as this will save a considerable amount of spot welding.
I have finished routing my first test pack and now i need to spot weld bus bars in the pack to reconnect it appropriately. when i hold wires in the bars places as i have not done this yet, it registers 47.3v which is double the previous voltage so it seems to be a success!

I now need to but a spot welder so I can finish attaching the bus bars, do you think I should use aluminium or nickel plate for this?

Alex


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## alex d (May 10, 2015)

these are the most recent pictures I have on my phone, ill take ones of the fully cut up module later, the red markings are the cut lines and the green markings show the pre made connection between a + and - terminal.

i plan on using an Orion bms, any thoughts here? the stock bms cant be used anyway unless the can is cracked and anyway it was designed for the previous configuration.

i'm hoping this configuration will allow me to pass 150kw of power to my motor and hopefully give around 160mi range, (the Tesla weighs over double and has double the capacity and seems to do 300mi ok )

any thoughts are very welcome!

Alex


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## AntronX (Feb 23, 2009)

Good luck. I also have tesla modules and their low voltage makes AC conversion difficult. I was thinking to use 100KW DC-DC boost converter and keeping original modules intact.


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## Karter2 (Nov 17, 2011)

As long as that 150kW is only in "bursts", you should be OK as that would only be ~ 380 amps from a ~ 120 Ahr pack.....so about 3C load peak.
But , if you are not using the original Tesla cooling systems, you should not expect to hold that for long.
Range is tricky to predict since it is much more a function of system efficiency...motor type, gearing, etc...and aero effects/ speed , driving style, road conditions, etc.
Remember, the Tesla has a much better aero design than a TR4 !
.......but not as much character !


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## dcb (Dec 5, 2009)

what material are the plates?

I would suggest using a thin dremel cutoff wheel or thin saw so you leave the most material fwiw.


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## alex d (May 10, 2015)

The plates are stamped saying aluminium grade 1100, I was thinking about using a cut ff wheel but there are too many curves. I am going to use a slightly smaller milling bit for the next ones but i want to prevent arcing and make sure they are not too close as well!


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## alex d (May 10, 2015)

I guess im too late but do you have a link to the dc/dc converter you found? what is the efficiency of it?

ill probably only do the 150kw bursts very rarely as i can imagine it to be pretty scary in such a small car! the most important thing is that it can complete a 100mi trip as that is the furthest i ever seem to go!

is a bms advised, ill need to send my Orion off to have more wires added if so.

alex


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## electro wrks (Mar 5, 2012)

If you are using an abrasive cut-off wheel (for the straight cuts), paraffin or candle wax rubbed on the wheel will keep it from loading up with aluminum. It may keep a carbide burr from loading-up too.


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## electro wrks (Mar 5, 2012)

AD, what are the dimensions of the Tesla packs? Also, could you point out the 6, 74p areas in the packs? They look to be odd, random sized areas. Also, are the fusible link wires on both the positive and negative ends of the cells?


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## alex d (May 10, 2015)

both ends of each cell have fusible links, the only part of the pack where you will see a plate connecting a cluster of 74 cells is on the plates that becomes the main positive and negative connection for the pack, all the other plates have 148 cells connected to them, this consists of the positive ends of a 74 cell cluster and the negative ends of a 74 cell cluster, these clusters are daisy-chained together with the appropriate plates on either side of the pack to form the module.


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## electro wrks (Mar 5, 2012)

I wonder if the cell pattern evens out the cooling by spreading out potential hot spots. You wrote that the modules weigh almost 26 kg. I would be interested in the length, width, and depth of the modules.

Thanks for your time.


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## Sunking (Aug 10, 2009)

At 50 vdc, don't expect any kind of meaningful speed. Grandma's in Golf carts will be passing you. With a 500 amp controller means something on the order of a 7 Kw or 6 hp motor. My golf cart has more HP at 16 hp, and 1/3 your weight. Wanna race?


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## Karter2 (Nov 17, 2011)

Sunking said:


> At 50 vdc, don't expect any kind of meaningful speed. Grandma's in Golf carts will be passing you. a 500 amp controller means something on the order of a 7 Kw 6 hp motor. My golf cart has more HP at 16 hp, and 1/3 your weight. Wanna race?



.....did you read the OP ?


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## Neal_Wallace (Apr 23, 2016)

Were you able to cut and reconfigure the Tesla pack? I have a 2001 SV650 and would like to reconfigure an authentic Tesla module. It seems it may be easier to just get separate 18650 cells. 

Sent from my Nexus 7 using Tapatalk


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## jimwebo (Mar 3, 2017)

Congratulations for your method and also for sharing.
There is too much secrecy about it.
I bought three modules and I want to make the modification to 12S, I will look for the best route for the cut, your photos are of great help ..
Do you have news of how your project is going?
And can you give me some advice before you start cutting?
A greeting.
Thank you.
Jim.


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## GoElectric (Nov 15, 2015)

You will see double-voltage modules are for sale elsewhere, and at a reasonable cost - I think it was 1,600/module. 

As far as a BMS goes, I think that is a good idea to use an Orion. You will of-course have to run 6 more wires from the 37P "cells," but that should work! 

EVTV has now hacked the Tesla BMS slave modules. And the Master too, I think, although I did not watch the entire video. So you could use two slave modules per double-voltage pack.


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## boekel (Nov 10, 2010)

I can give some advice:

drawings here:
http://www.diyelectriccar.com/forum...s-conversion-succesfull-prototype-182226.html

-don't hit the fuse-wires
-don't short out the positive poles with aluminium chips
-use a spiral groove router bit made for aluminum 
-seal the groove with electrical grade silicone sealer
-make a -good- connection to close the 12S loop...only thing I've been able to come up with is with a CD Stud Welder, I use M6 bolts for the connections, and M4 bolts for the balance wires.


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## jimwebo (Mar 3, 2017)

[Quote = boekel; 853065] puedo dar un consejo: 

dibujos aquí: 
http://www.diyelectriccar.com/forum...s-conversion-succesfull-prototype-182226.html

-don ' t golpear los fusibles de cables 
-no cortocircuitar los polos positivos con virutas de aluminio 
-Utilizar una fresa de ranura en espiral hecha de aluminio 
-seal la ranura con un sellador de silicona de calidad eléctrica 
-hacer una conexión -good- para cerrar el bucle 12S. lo ..only que he sido capaz de llegar a es con un CD Stud soldador, yo uso pernos M6 para las conexiones y tornillos M4 para los cables de equilibrio. [/ quote]




Thank you very much, great work.
I'm glad you share this information.
I'm going to use a dremel with milling attachment.
Do you think it will do it?
Thanks again .
Jim.


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## jimwebo (Mar 3, 2017)

by the way.
The soldering of the bolts by discharge of capacitors is DIY?
Can I use my 4F spot welder for this?
Thanks.
Jim


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## boekel (Nov 10, 2010)

jimwebo said:


> Thank you very much, great work.
> I'm glad you share this information.
> I'm going to use a dremel with milling attachment.
> Do you think it will do it?
> ...


It is theoretically possible, but I wouldnt do it, one little mistake and you have a 36S pack instead of 37S (hit a fuse wire, I did this on the prototype module, with a cnc cut route...)
Where are you going to rest the dremel? 
I use a 4mm router bit, because a 3mm bit is to flexible and gives a rough cut.












jimwebo said:


> by the way.
> The soldering of the bolts by discharge of capacitors is DIY?
> Can I use my 4F spot welder for this?
> Thanks.
> Jim


What is a 4F spot welder? a tab-welder? don't know if it is possible, you coult try on a piece of soft aluminum.
What maximum current do you want to draw on your pack?

I use this welder:
https://weldingshop.nl/index.php?it...action=article&group_id=138&aid=49361&lang=nl


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