# Tesla Model 3 Battery Pack Architecture



## garsh (Apr 4, 2016)

Full article:
Tesla Model 3: Exclusive first look at Tesla's new battery pack architecture

So, the CAD drawing we were shown at the Model 3 reveal was NOT of the final design.
The pack has four modules.
50kWh battery: 31 cells per "brick", 23 bricks in outer modules, 25 bricks in inner modules.
74kWh battery: 46 cells per "brick", 23 bricks in outer modules, 25 bricks in inner modules.









Here's a diagram of the pack's electronics.








1. Charge port connector 
2. Fast charge contactor assembly 
3. Coolant line to PCS 
4. PCS - Power Conversion System 
5. HVC - High Voltage Controller 
6. Low voltage connector to HVC from the vehicle 
7. 12V output from PCS 
8. Positive HV power switch 
9. Coolant line to PCS 
10. HV connector to cabin heater and compressor 
11. Cabin heater, compressor and PCS DC output fuse 
12. HV connector to rear drive unit 
13. HV pyro fuse 
14. ?
15. HV connector to front drive unit 
16. Negative HV power switch 
17. Connector for 3 phase AC charging

And diagrams of the assembled pack:


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## KennethK (Oct 13, 2016)

I just hope that the reliability of the system is high. Hopefully the components are still easily accessible and swap-able.

So the Gigafactory is really assembling a large part of the vehicle if the whole battery assembly/ controls are one component.


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## KennethK (Oct 13, 2016)

So the electronic assembly probably is located somewhere under the rear seat. I love seeing all these detailed drawings!

I didn't know that the "powertrain" generated enough heat to warm the batteries.


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## garsh (Apr 4, 2016)

KennethK said:


> I just hope that the reliability of the system is high. Hopefully the components are still easily accessible and swap-able.


It sounds like swapping a battery pack will be more involved than for an S or X.
According to the article, the bolts are accessible from above instead of below, so parts of the interior would have to be removed.

So, definitely no fast battery swapping stations for this car.


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## KennethK (Oct 13, 2016)

garsh said:


> It sounds like swapping a battery pack will be more involved than for an S or X.
> According to the article, the bolts are accessible from above instead of below, so parts of the interior would have to be removed.
> 
> So, definitely no fast battery swapping stations for this car.


The battery pack as a whole, yes, will be more time consuming than an S or X. But, I was referring to individual components, like the AC/DC charger or other components. Probably pop up the rear seat, unbolt a cover and pull out the components.


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## TrevP (Oct 20, 2015)

With this new design battery swapping is effectively dead. Tesla is putting all their efforts into Supercharging as if their network expansion wasn't proof enough 

If find it very intriguing how they're using software to control the motor outpost to effectively 0 in order to generate heat for the battery pack thermal management system. Just goes to show how much effort was put into finding more efficient ways that will result in cost savings. If this works well, and it should if they're going into mass production of it, I can expect a lot of these new methods to eventually make its way into their other cars.

It's all becoming more clear now what Elon meant during the last fainancial call that they're going to bring Model S and X up to the same tech level as Model 3 soon.


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## Akilae (Jan 16, 2017)

TrevP said:


> With this new design battery swapping is effectively dead. Tesla is putting all their efforts into Supercharging as if their network expansion wasn't proof enough
> 
> If find it very intriguing how they're using software to control the motor outpost to effectively 0 in order to generate heat for the battery pack thermal management system. Just goes to show how much effort was put into finding more efficient ways that will result in cost savings. If this works well, and it should if they're going into mass production of it, I can expect a lot of these new methods to eventually make its way into their other cars.
> 
> It's all becoming more clear now what Elon meant during the last fainancial call that they're going to bring Model S and X up to the same tech level as Model 3 soon.


Also a good reason to keep away from CPOs right now and wait for the 3 (trying to convince myself right now  ).


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## garsh (Apr 4, 2016)

garsh said:


> 50kWh battery: 31 cells per "brick", 23 bricks in outer modules, 25 bricks in inner modules.
> 74kWh battery: 46 cells per "brick", 23 bricks in outer modules, 25 bricks in inner modules.


I was thinking about those per-brick cell counts. It's strange that they don't have a common multiple.

But then I remembered some talk about potentially having "extra" cells in the pack that only get used if a cell goes bad. Perhaps the cells are in groups of 15, and each brick has a single "spare" cell (30+1 and 45+1).

Just thinking out-loud.


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## garsh (Apr 4, 2016)

garsh said:


> 74kWh battery: 46 cells per "brick", 23 bricks in outer modules, 25 bricks in inner modules.


Also, 46*(23+23+25+25) = 4416 cells in the large battery pack.
Bringing us back to the Teslanomics video where Ben mentions that the pack is using 4416 cells.

So, @Meros wins! 

https://teslaownersonline.com/threads/tesla-could-be-using-a-"4416"-battery-cell-in-model-3-and-next-gen-s-x-fleet.4367/page-3#post-33658


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## MelindaV (Apr 2, 2016)

garsh said:


> 14. ?


comments in the article are listing #14 as a pyro switch.  I don't know what that is, but seems logical, being next to a pyro fuse


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## Skione65 (Apr 4, 2016)

MelindaV said:


> comments in the article are listing #14 as a pyro switch. I don't know what that is, but seems logical, being next to a pyro fuse


@MelindaV,

The PSS is a new safety system to 'quick-disconnect' and bypass either a faulty battery or especially in an accident or post accident for passenger safety. Also used occasionally 'in-line' in airbag systems. Here is a not too long read...10 pages on new design PSS's as they pertain to new generation EVs in particular. Auto-Aliv is one of the top manufacturers. Very interesting read. Enjoy!

https://www-esv.nhtsa.dot.gov/Proceedings/24/files/24ESV-000163.PDF

Ski


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## Model34mePlease (Jun 3, 2017)

What is the shape of the battery 'brick' that yields an odd number in each module? It is interesting that the picture shows 12 'repeats' along the smaller one and 13 'repeats' in the larger one. Is it possible that it is really 24 (2x12) bricks in the smaller and 26 (2x13) bricks in the larger? That would yield the same total number of bricks.

Also, what is the function of '17. Connector for 3 phase AC charging', as opposed to '1. Charge port connector' (which I would think goes to the SC port)?


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## JimB (May 11, 2016)

I don't know why, but I'm always interested in how the cells are interconnected and I have not seen any other post about it. Here's my take on it.

I've seen the cell voltage as either 3.6v or 3.78v. Assume it is 3.78v.

So, if the cells in a brick are connected in parallel and the bricks are connected in series and the modules are connected in series. Then:
The output of the 23 brick module would be 3.78 x 23 = 87v
The 25 brick one would be 95v. Adding the 4 modules would be 364v. Sounds about right.

Also, going from 50 kWh to 74 kWh adds cells in the parallel connected brick, so the voltage does not change.

Maybe this is obvious.


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## Tom Bodera (Aug 10, 2016)

Great discussion guys. I am curious on using the motor to generate heat with zero torque. Would that mean tryign to spin the motor one way and reverse very quickly to create countering torque to heat up the windings without moving?

"10. HV connector to cabin heater and compressor"
Also "HV - High Voltage" could they not have used the cabin heater to heat the battery pack through a loop?That way excess motor heat on the same loop could have been used to heat the cabin and cool the loop. 

Lastly any thoughts on the compressor being AirCon only or heat pump?


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## garsh (Apr 4, 2016)

Tom Bodera said:


> Great discussion guys. I am curious on using the motor to generate heat with zero torque. Would that mean tryign to spin the motor one way and reverse very quickly to create countering torque to heat up the windings without moving?


Probably not.

To make the motor spin, you need to send it an AC waveform. A magnetic field is created by a *changing* electrical field. If all you want to do is to generate heat, you could probably just provide a constant DC voltage, and have it (the stator of the motor) act like a resistive heater. Since the electrical field isn't changing, no magnetic field will be created, and the rotors won't move.

But, that's just a guess.


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## John (Apr 16, 2016)

Gotta love that every Model 3 comes standard with *An Explosive Guillotine.*


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## Roderick80 (Jul 21, 2017)

sorry for the noob question, but how is the coolant dispersed through this particular battery pack and is it different than what occurs on the X/S? I can't tell from the diagram.


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## garsh (Apr 4, 2016)

garsh said:


> To make the motor spin, you need to send it an AC waveform. A magnetic field is created by a *changing* electrical field. If all you want to do is to generate heat, you could probably just provide a constant DC voltage, and have it (the stator of the motor) act like a resistive heater. Since the electrical field isn't changing, no magnetic field will be created, and the rotors won't move.


I was also thinking that the inverter might not have been designed to deliver a DC voltage to the motor. So, another possibility would be to send a very high-frequency AC waveform to the motor. If the motor is sitting still, it will basically not have time to spin in one direction - the magnetic field will have moved and started pulling it in the other direction before it gets started. Combine that with a parking brake to keep things from "shuddering".

In other words @Tom Bodera , you might be right. 
Well, mostly. It wouldn't _really_ be the inverter trying to spin it one way, then the other. The inverter would just be driving the AC waveform too fast for the rotor to start following along.

Here's a good video explaining the "start up problem" with synchronous motors.
Basically, Tesla could be making use of this "issue" to have the drive units generate heat w/o moving.
I've linked to 1:54, which describes startup. The whole video is interesting though.


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## JWardell (May 9, 2016)

#14 is the pyro fuse, not 13. It is shown as the tallish black module in the first photo.
#13 appears to be a bus bar with small wire connector coming out of the top, most likely a current sense for overall current draw

I should also note I like the innovation of the pyro fuse.
Breaking very large currents is extremely difficult, and a normal switch or fuse will just cause the current to jump the gap. Typically this requires a large, heavy, and expensive contractor with giant contacts as well as magnets to guide the electric field. That's a lot of extra expense and weight for something that would only be used once during an emergency. Here Tesla uses pyrotechnics to blow a much larger gap than would occur with a fuse or breaker, not to mention has zero heat loss as there is no thin fuse wire to heat.


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## Kizzy (Jul 25, 2016)

JWardell said:


> I should also note I like the innovation of the pyro fuse.


I'm slightly amused by the car having a kind of self-destruct mechanism. "Like a spaceship" indeed!


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## JimB (May 11, 2016)

garsh said:


> I was also thinking that the inverter might not have been designed to deliver a DC voltage to the motor. So, another possibility would be to send a very high-frequency AC waveform to the motor. If the motor is sitting still, it will basically not have time to spin in one direction - the magnetic field will have moved and started pulling it in the other direction before it gets started. Combine that with a parking brake to keep things from "shuddering".
> 
> In other words @Tom Bodera , you might be right.
> Well, mostly. It wouldn't _really_ be the inverter trying to spin it one way, then the other. The inverter would just be driving the AC waveform too fast for the rotor to start following along.
> ...


After watching that video, I'm now concerned about starting on steep hills.


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## garsh (Apr 4, 2016)

JimB said:


> After watching that video, I'm now concerned about starting on steep hills.


Don't be. The inverter control electronics they have nowadays are very good. It used to be that we could only create AC waveforms at a single frequency, so having a synchronous motor lose phase under load could be an issue.


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## JimB (May 11, 2016)

garsh said:


> Don't be. The inverter control electronics they have nowadays are very good. It used to be that we could only create AC waveforms at a single frequency, so having a synchronous motor lose phase under load could be an issue.


Thanks. There a lot very steep driveways around here.


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## Guest (Aug 26, 2017)

JimB said:


> Also, going from 50 kWh to 74 kWh adds cells in the parallel connected brick, so the voltage does not change.


If that would be true, I would be really happy.

PS: With this battery module design, it is, technically, possible to switch between 400V and 800V chains using few extra relays. Reason is that the middle part of the pack is right where it should be for rewiring.


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## Badback (Apr 7, 2016)

Model34mePlease said:


> What is the shape of the battery 'brick' that yields an odd number in each module? It is interesting that the picture shows 12 'repeats' along the smaller one and 13 'repeats' in the larger one. Is it possible that it is really 24 (2x12) bricks in the smaller and 26 (2x13) bricks in the larger? That would yield the same total number of bricks.
> 
> Also, what is the function of '17. Connector for 3 phase AC charging', as opposed to '1. Charge port connector' (which I would think goes to the SC port)?


Three-phase charging is a European thing as three-phase is quite common there, SCs are DC.


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## Model34mePlease (Jun 3, 2017)

Badback said:


> Three-phase charging is a European thing as three-phase is quite common there, SCs are DC.


Do European cars have another charge connector on the outside, or is that charging method available through the SC port? Is it faster than 240V charging? I ask because I actually have 3 phase power available at my home.


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## MelindaV (Apr 2, 2016)

Model34mePlease said:


> Do European cars have another charge connector on the outside, or is that charging method available through the SC port? Is it faster than 240V charging? I ask because I actually have 3 phase power available at my home.


the Euro tesla connector is different.








so if thinking you could order up a Euro spec'd car and charge faster at home, you would be out for all other charging options in NA without a custom adaptor. There are some that brought Euro cars over to NA and made adaptors to work, but not sure that they worked with Superchargers.


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## Guest (Aug 27, 2017)

It's not EURO connection. It is non-US connector. AFAIK only US (on big picture) does not have 3 phase at least somewhat common. And US connector is, AFAIK, only in US. Not even Canada.


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## MelindaV (Apr 2, 2016)

arnis said:


> It's not EURO connection. It is non-US connector. AFAIK only US (on big picture) does not have 3 phase at least somewhat common. And US connector is, AFAIK, only in US. Not even Canada.


US and Canada cars have the same connection


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## Guest (Aug 27, 2017)

Oh crap. My bad. It would be impossible to travel to Canada with SC network.


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## Model34mePlease (Jun 3, 2017)

There seem to be a whole bunch of SCs in Europe, so that must work with SCs, no?


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## MelindaV (Apr 2, 2016)

Model34mePlease said:


> There seem to be a whole bunch of SCs in Europe, so that must work with SCs, no?
> 
> View attachment 3081


the superchargers in those locations have that same corresponding plug, not the plug used in NA.


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## Thomas Mikl (Jun 26, 2017)

Guys do not worry about the motor. We will prolly not see the complete design for a while (if ever) and today no motor is a synchronous or asynchronos motor as per definition.
With a permanent magnet motor even Toyota has experimented to make it "somewhat" asynchonous by moving the magnets with rotational force, some asynchonous designs use "pre-load" currents to make it synchronous in special conditions etc. etc. etc.

So unless they would show us the full design specs of the motor and all feeding components and algorithms, speculation is really just looking into a bowl of soup and guessing the amount of carrots.


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