# 85 Kwh Tesla battery teardown - questions?



## boekel (Nov 10, 2010)

Tomorrow I'll start tearing down a 85 Kwh battery, and if people want detailed pictures of specific areas / things, please leave a comment.

Of this pack 4 modules will be used in a small (7m) boat, in a 2s2p configuration. the rest are not yet intended for a specific project, I do want to look into possible 12s configuration.


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## bchaffin72 (Jan 4, 2017)

I'm interested. Since you're going to be tearing it down anyway, I'd love to see some documentation of the process. Whatever you think is relevant or catches your interest about how it's built.


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## kennybobby (Aug 10, 2012)

Will you be able to open it up/ remove the lid, without damaging it--such that it could be closed back up or reused? Or is that too much trouble? This would be an interesting question that you could answer.


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## boekel (Nov 10, 2010)

kennybobby said:


> Will you be able to open it up/ remove the lid, without damaging it--such that it could be closed back up or reused? Or is that too much trouble? This would be an interesting question that you could answer.


Looking at other teardowns I doubt that's an option, but I'll look into it.

I'd like to use a complete battery (or two) in my own boat in the feature (both household use and propulsion), so it would be super cool if the built in BMS will be hacked for diy use someday.
(doing that is way out of my league, will have to wait for smarter people to do that)


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## kennybobby (Aug 10, 2012)

i have traced the board and identified the components, was considering trying to get the firmware and reverse it all the way--but i like Wolf's approach better, just buy a blank microcontroller and solder it on, then write a new program to use the board for balancing and reporting. Don't need to know all the details of tesla's code, just want to use the board...

is anyone up for that challenge?


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## oudevolvo (Mar 10, 2015)

boekel said:


> so it would be super cool if the built in BMS will be hacked for diy use someday.


Looks like EVTV is working on that 
https://youtu.be/bUWwZme4DIc?t=1h12m21s
At 1:13:27 "By the way we can turn on the battery and get that information now. It resets after a few minutes. .... It's looking for some CAN that I have to provide."


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## Tomdb (Jan 28, 2013)

The built in bms has a serial bus between each slave module. 
EVTV want to get the canbus side, so the complete pack, working which is good if you want to use the whole pack. 

You can see what the pack does when you give it 12 volts, if there is any can messages being sent. And then what the internal serial bus is doing.


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## GoElectric (Nov 15, 2015)

I'd like to know a small detail about the modules if you end-up taking one apart: there are two thermistor outputs on one end of each module - are the thermistors right there at the edge of the pack, or embedded part way in?


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## boekel (Nov 10, 2010)

All pictures:
http://boekel.nu/foto/17/2017-01-tesla/

All went well, I'll go into details later, bedtime for me...


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## Yabert (Feb 7, 2010)

Absolutely beautiful.... Thanks a lot.


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## GoElectric (Nov 15, 2015)

Thanks! I'll save that link for when I do one. I have someone interested in putting a Tesla drive train into a stretch limo.

One question (of many to follow, I think): could you tell if the weight of the modules was being supported by the rails on the side?


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## boekel (Nov 10, 2010)

GoElectric said:


> One question (of many to follow, I think): could you tell if the weight of the modules was being supported by the rails on the side?


Yes! that's where you want to carry / fix them. Should be quite easy to make battery boxes.

Also, the BMS is saying 'hello world', a very dim white led strobe can be seen but only if its dark around you.

Unfortunately the main wiring harness is potted in, so the bms wiring can't be removed intact.


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## GoElectric (Nov 15, 2015)

Hi, thanks and good to know. 

Big debate over Tesla BMS - just to be clear, the whole system is still intact; you don't have individual modules looking for their mommy?

Anyway, I enjoyed looking at your pictures and will do it again, only this time try to get them in order. By pushing the Next button they were jumbled-up. 

If this is not an intrusion - or high-jacking your thread - I'd be interested to know where/how you got the pack. Not specifically, but I gather you did not pull it out of a car, so how the heck do you get something like that delivered?

Jim


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## boekel (Nov 10, 2010)

I did add some phone-pictures shortly after publishing...they came in front of the other pictures, F5 should do the trick.

I got the pack from a wrecker, car had burn damage to the front, battery not affected and no signs of heavy crash.

Edit: the pack was a 1,5 hour drive away, my dad (retired) picked it up for me.


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## boekel (Nov 10, 2010)

So...story time!

Found a battery pack from a 2015 Tesla with light left front crash damage and fire damage also to front left. 1,5 hours drive away.



















I first drained most of the coolant, was a little messy due to not having correct sized hose, basically just added air pressure to one port and pushed open the other. No pictures due to hands full 









The pack is covered with a plastic sheet, held on there with tackytape.


















Underneath is a (fire?) insulation blanked, also in plastic. It's about 8mm thick.









Lots of screws underneath, and some mounting bushes.


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## boekel (Nov 10, 2010)

'Database error on the forum, don't know when this can be posted...

I first opened the smal cover:


















Pack voltage









The control PCB, contacters and connectors are here.


















Precharge resistor is underneath, I didn't trace it but assume it is activated via the relay on the control board.




































All connectors are nicely labeled.









two Jtag headers


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## boekel (Nov 10, 2010)

Lots of fasteners...









The (aluminium) bushes have a left-hand thread.









hex10mm


















front 'hump'









looks like a vent..



























The two stacked modules.









insulation cover plates


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## boekel (Nov 10, 2010)

.8mm thick









watercooling connections these ones are easy to undo


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## Tomdb (Jan 28, 2013)

Got any higher resolution pictures of the main bms board?


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## boekel (Nov 10, 2010)

the bus-bars are hard to reach here, so I went to the other modules first (to be able to isolate these modules, making it safer to work on)

In the white translucent cover is the HV fuse, also difficult to reach, there's a cover underneath, but I didn't have the correct tool for the 6 lobe screws.









Carefully pried open the cover, a claw hammer (!) turned out to be a relatively save tool, because you can't 'shoot through'damaging or potentially shorting cells.
(I also wore thick rubber gloves and a safety shield until there was no more 'hv' risk.)









Some of the covers were sticking to the cover, carefull 'massaging' got most of them back, two covers I had to use a knife to cut loose the sealant.









No need to write it, but just in case: if you do this yourself: without the thin plastic cover, you can easily touch or damage the fuse wires!









Portside open!









Uncovered...


















The modules are secured between these black anodised aluminium profiles and corresponding carriers in the box.


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## boekel (Nov 10, 2010)

To remove the modules I first removed all busbar bolts (13mm socket).
Pulling the modules out would be easier if you have 3 or 4 hands...one coolant connector can be undone with the module in place, the other can only be done with the module lifted above the edge of the box.









The coolant tubes are 8mm outer diameter.









The quick-connect hose thingies 









sorry, no better picture.









The BMS boards.


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## boekel (Nov 10, 2010)

The coolant side of the module.
Coolant flows through a 'flat pipe' making contact with each cell through a (silicone?) white rubber heat transfer strip.









Topside without plastic cover.
I can imagine a battery module with a thinner (and shaped) coolant line can hold quite some extra cells...




































Underside of the module


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## boekel (Nov 10, 2010)

The margin you have when opening a pack...


















HV fuse is underneath.









I didn't have the correct 5 lobe bit...



























I got it out with the busbarrs.









the 'cover' is also what the fuse bolts to.


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## boekel (Nov 10, 2010)

Tomdb said:


> Got any higher resolution pictures of the main bms board?


no good ones, I dropped them here anyway:
http://boekel.nu/foto/17/2017-01-tesla/highres/

I did bring one battery module home with me, I can undo the bms board on that one to make pictures, and i -might- send it to you 

btw the bms boards are all connected in a loop.


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## boekel (Nov 10, 2010)

30cm interval.

















































































The modules are further apart where mounting bolts have to go inbetween.


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## Tomdb (Jan 28, 2013)

I would love some good pics of these Revision 2 boards, it mainly just looks like a shuffle of the components. Question becomes what kind of protocol is used on the bus, might be worth trying to sniff it out, to see if any data gets put onto the bus as soon as they power up.


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## boekel (Nov 10, 2010)

End of the (water) line..









All modules have their own sealed compartments, silicone rubber sealings around the water lines.


















The dividers / carriers are glued in place...with a very special glue...









Metal shavings in / on the glue...looks like no good cleanup...but might be very special conductive glue? 









half of the busbars are straght across


















Others have already shown they're made up of thin layers of copper.


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## boekel (Nov 10, 2010)

Tomdb said:


> I would love some good pics of these Revision 2 boards, it mainly just looks like a shuffle of the components. Question becomes what kind of protocol is used on the bus, might be worth trying to sniff it out, to see if any data gets put onto the bus as soon as they power up.


I might have to send you the main board too then...if you promise to share your findings with the world...


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## boekel (Nov 10, 2010)

All modules out...finished?









There's a steel protective cover on both sides, covering the vents.









Per module two one way valves (check valves?) and 4 more plastic plugs, presumably to melt away and open in case of fire?



























a rubber valve disc.


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## boekel (Nov 10, 2010)

Something I only found out removing the last parts (hv contacters)













































Whoops...no more warranty...





































There is a plug underneath the pack leading directly to the hv lines of the battery, easy way to measure pack voltage before you buy a pack.
'emergency crew' acces...do they have a special plug to short out the pack and blow the main fuse?


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## boekel (Nov 10, 2010)

BMS plugs, left for a battery module, right for the main board, all the same wires only different plug.









contacters.


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## boekel (Nov 10, 2010)

Starting opening the 'spline' of the pack.


















BMS plug, one half to previous board, other half to next.


















bus bars




































Whoops...

With a bit of time (about one hour I think) you could get all the wiring out of the rubber without damage, I only did two pieces yet.


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## boekel (Nov 10, 2010)

Main cable in the bottom of the spline.


















extra insulation.









Same 'mica like' material as the sheets.









do-able.


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## boekel (Nov 10, 2010)

So...bring the box to the scrapyard?









Partly...









Chop it up!









Might use this for a 4 module pack...with room for contacters...and possibly main bms board...









other possible 4 module battery case 

So...any questions?
(btw, I have modules for sale, need 4 for a boat conversion so the rest is available)


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## electro wrks (Mar 5, 2012)

The silicone-mica tubes make sense to reduce the chance of a dead short between the high voltage power cables in case of a fire and the insulation melts. Save the red and clear pop-off valves; and the silicone-mica sheets if you want to duplicate the Tesla fire safety features in your battery boxes. Here's Tesla's patent that describes why they need the valves and how they work:

http://redirect.viglink.com/?format...=https://www.google.com/patents/US20120231306 

Can you measure the diameter of the holes the valves fit in?


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## Tomdb (Jan 28, 2013)

boekel said:


> I might have to send you the main board too then...if you promise to share your findings with the world...


I will, just like i did with the Honda IMA inverter and Chevy volt inverter. For me reverse engineering is like crosswords, keeps me off the street. 

Btw, great teardown pics, so through some good reference material to figure out how certain things work.


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## Moltenmetal (Mar 20, 2014)

Thanks so much for these teardown pics!

Wow- just amazed at the complexity...and puzzled. The Volt and Leaf pack configurations make so much more sense to me...the pack build cost for these things must be enormous and it's tough to imagine how it would get too much cheaper even if they scale up massively.


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## kennybobby (Aug 10, 2012)

What's the part number of the big fuse, if you remove the orange housing to see the vendor info, etc?

Also that connector behind the 6-lobe socket head cover--does it go directly to pack + and - , and bypass the contactors? It could be used by the factory to charge or discharge the pack during servicing, or a safety feature such as you mentioned. We'll have to ask Ingineer over at TMC.


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## boekel (Nov 10, 2010)

electro wrks said:


> The silicone-mica tubes make sense to reduce the chance of a dead short between the high voltage power cables in case of a fire and the insulation melts. Save the red and clear pop-off valves; and the silicone-mica sheets if you want to duplicate the Tesla fire safety features in your battery boxes. Here's Tesla's patent that describes why they need the valves and how they work:
> 
> http://redirect.viglink.com/?format...=https://www.google.com/patents/US20120231306
> 
> Can you measure the diameter of the holes the valves fit in?


Thanks for the link! I'll measure them later.



kennybobby said:


> What's the part number of the big fuse, if you remove the orange housing to see the vendor info, etc?


I can look into that later.



> Also that connector behind the 6-lobe socket head cover--does it go directly to pack + and - , and bypass the contactors? It could be used by the factory to charge or discharge the pack during servicing, or a safety feature such as you mentioned. We'll have to ask Ingineer over at TMC.


Yes it goes straight to the pack.


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## boekel (Nov 10, 2010)

Better pictures of the boards:
http://boekel.nu/foto/17/2017-01-tesla/highres/


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## kennybobby (Aug 10, 2012)

Thank you for the HR pictures.

There is an led, D100, in the upper right of that board, which may have been winking at you when the cell monitoring boards are plugged in.


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## boekel (Nov 10, 2010)

kennybobby said:


> Thank you for the HR pictures.
> 
> There is an led, D100, in the upper right of that board, which may have been winking at you when the cell monitoring boards are plugged in.


That's correct.


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## SWF (Nov 23, 2007)

boekel said:


> So...any questions?


Great job documenting the tear down. Sent you a PM with some potential small component purchase questions.

How thick is the material (aluminum?) that forms the bottom of the pack enclosure? Just curious how much impact protection there is between the modules and the road. Did the modules sit fairly snug against the mica sheets at the bottom or was there some air gap?


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## boekel (Nov 10, 2010)

SWF said:


> Great job documenting the tear down. Sent you a PM with some potential small component purchase questions.
> 
> How thick is the material (aluminum?) that forms the bottom of the pack enclosure? Just curious how much impact protection there is between the modules and the road. Did the modules sit fairly snug against the mica sheets at the bottom or was there some air gap?


I'll have to measure the thickness of the bottom.
there is about 4,5 - 5 mm space between the mica sheets and the module.


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## boekel (Nov 10, 2010)

Updates:



electro wrks said:


> Can you measure the diameter of the holes the valves fit in?


They're 26mm diameter, but I forgot to check thickness.



kennybobby said:


> What's the part number of the big fuse, if you remove the orange housing to see the vendor info, etc?


No other information on it, it looks like the white housing is glued around a standard fuse as a containment enclosure.



> Also that connector behind the 6-lobe socket head cover--does it go directly to pack + and - , and bypass the contactors? It could be used by the factory to charge or discharge the pack during servicing, or a safety feature such as you mentioned. We'll have to ask Ingineer over at TMC.


It goes straight to the pack, but it has a 20A fuse in the wiring.


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## kennybobby (Aug 10, 2012)

Thanks for uncovering some unknown aspects about the tesla pack.

There was a comment on the tesla forum that the connector behind the 6-lobe cover was to drain the pack before servicing, but i doubt that anyone knew about the 20-amp fuse which would make it a slow process.

The main pack fuse has been a subject of speculation that it was changed for something "smart" when they went to larger capacity and higher currents--but it doesn't appear to have any sort of CAN buss or control lines does it? The older version was just a big dumb fuse:


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## boekel (Nov 10, 2010)

kennybobby said:


> The main pack fuse has been a subject of speculation that it was changed for something "smart" when they went to larger capacity and higher currents--but it doesn't appear to have any sort of CAN buss or control lines does it? The older version was just a big dumb fuse:


I doubt it's anything special


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## boekel (Nov 10, 2010)

Something I forgot to check earlier:









If you want to design a battery box...









The carriers are about 56,5mm high

Another question was the location of the temperature sensors:









Follow the blue and yellow wires and find them...









They're pushed against a single cell.
Also visible the rubbery (silicone?) heat transfer strips, and in between the rows of cells a smooth clear coated woven seperator.


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## Karter2 (Nov 17, 2011)

Just curious...
..do you really think those silicone strips are for "heat transfer" ??
..Silicone is a very good heat insulator, so it would seem an odd choice to act as a thermal transfer medium.
Or is it some other material ?


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## boekel (Nov 10, 2010)

Karter2 said:


> Just curious...
> ..do you really think those silicone strips are for "heat transfer" ??
> ..Silicone is a very good heat insulator, so it would seem an odd choice to act as a thermal transfer medium.
> Or is it some other material ?


I don't know the material type, but it reminds me of (silicone) heat transfer pads, like this:

http://solutions.3m.com/wps/portal/...Thermally-Conductive-Interface-Pads?N=8704982


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## boekel (Nov 10, 2010)

More measurements:



















The whole bottom of the pack is 6,5mm (just over 1/4")









Ok a little thinner here...









The outside of the pack is an extruded profile, welded to a plate that forms the bottom.


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## SWF (Nov 23, 2007)

boekel said:


> More measurements:


Thank you. For those of us building enclosures for tesla modules, these are useful to know.


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## GoElectric (Nov 15, 2015)

I have found all dimensions are in inches, nice!


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## GoElectric (Nov 15, 2015)

RE heat-conducting strips a page back:

I agree, it looks like an odd choice for material and form-factor, but I read the Tesla patent for the battery temperature control system, and it is indeed for heat-transfer. There was a diagram with explanation and it looked exactly the same.


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## boekel (Nov 10, 2010)

GoElectric said:


> I have found all dimensions are in inches, nice!


What do you mean by this?


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## GoElectric (Nov 15, 2015)

I mean everything I have measured on these cars comes out in nice round numbers when I use imperial units. The modules are for example 1"above the flange, 2" below the flange and the flange is 1/8". He measured the aluminum extrusion, and it was nominally 1/4". 

I see some of the measurements in the tear-down are in metric, some are imperial - I think imperial is the standard they are using, that's-all.

Jim


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## boekel (Nov 10, 2010)

More pictures:

http://boekel.nu/foto/17/2017-02-tesla/index.htm


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## annerajb (Jul 27, 2016)

do you recall the part number of the MCU's on the main bms board?


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## boekel (Nov 10, 2010)

annerajb said:


> do you recall the part number of the MCU's on the main bms board?


I can't make them out on the pictures, will check tonight.

http://boekel.nu/foto/17/2017-01-tesla/index11.htm


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## boekel (Nov 10, 2010)

more pictures:
http://boekel.nu/foto/17/2017-19_bms/index.htm

If you want I can send you a bms board and slave board...


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## annerajb (Jul 27, 2016)

Thanks I'll send you a PM.


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## Jimbo69ny (Feb 13, 2018)

Great thread! Thank you!


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