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Inside the Tesla battery pack
- Thread starter Ingineer
- Start date
gg_got_a_tesla
Model S: VIN 65513, Model 3: VIN 1913
Amen! Happy to gawk at it and learn more as long as it's not my battery pack. Thanks, Phil.
Telsa might have you do an MVPA to get a Model S, but does Toyota do that when you buy a RAV4EV ?
For what it is, Phil's pictures portray a work of art from what I can see.
Tesla creates well engineered objects of nerd beauty.
Hells yes. This!
Well not my car until the warranty is up. I am all for tinkering and messing around but I normally wait for the warranty to expire before I do anything serious. Like say opening up a battery pack.
mknox
Well-Known Member
+1 I was thinking the same thing myself. I don't recall ever seeing debate like this when the new iPhone is dissected and broken down into costed components (and we all know how Apple can be!).
lolachampcar
Well-Known Member
Phil,
You are the man and PLEASE post more pics (or point me to your site so I can see more). I'd love to understand the engineering and have no desire to ever build a pack myself.
As for changing cooling fluids and providing manuals, please do not get me back up on that milk create. Large OEMs are obliged to provide service manuals for third party service providers and documentation to their diagnostic interface so that people like AutoLogics can build test tools (that even support module re-programming). Even little ole non-cooperative Ferrari has to do it although they throw up as many obstacles along the way as they possibly can.
You are the man and PLEASE post more pics (or point me to your site so I can see more). I'd love to understand the engineering and have no desire to ever build a pack myself.
As for changing cooling fluids and providing manuals, please do not get me back up on that milk create. Large OEMs are obliged to provide service manuals for third party service providers and documentation to their diagnostic interface so that people like AutoLogics can build test tools (that even support module re-programming). Even little ole non-cooperative Ferrari has to do it although they throw up as many obstacles along the way as they possibly can.
Excellent! Presumably this is an 85 kwh battery.
The next issue is going to be the control protocols for the battery. If third parties are going to be able to reload these with new and/or higher power cells they're going to have to reverse engineer the communication link between the battery and the car. Hopefully Tesla didn't encrypt it.
The next issue is going to be the control protocols for the battery. If third parties are going to be able to reload these with new and/or higher power cells they're going to have to reverse engineer the communication link between the battery and the car. Hopefully Tesla didn't encrypt it.
timdorr
Model S P90D w/AP3.0
Honestly, given that Tesla is such a thought leader in this space, I doubt I'm ever going to trust any sort of third-party battery pack for a Model S. They would have to be some top-notch MIT grads for me to even give them the time of day.
You can be quite confident that every major car manufacturer has, or soon will, tear these things apart to see how they work. Next will be the hot rod and performance folks. If Tesla sells enough of them, you can also expect that there will be an aftermarket develop for replacement and upgrade parts. Bought a 60kw car and after 5 years want it to be an 100kw car? If Tesla won't sell you the upgrade, you can bet someone else will. Saleen, Rousch, NAPA, and all of the boy-racer speed shops have been doing it for years with varying degrees of factory support. The aftermarket for performance and upgrade parts is worth billions of dollars and employs 1000s of people. All of those businesses and people are not going away because we all decide to drive EVs. Also, there are laws that protect the industry's ability to sell these aftermarket parts. Most important, it's human nature to take whatever we have and make it faster. It will be fascinating to see what develops in the future.
The thing is, Tesla could already make a crazy supercar version of model s. Assuming peak current draw is already near the max for these cells, just wire the pack differently (in parallel) to double the current output, beef up the electronics (and whatever else) and put in a 900 hp motor. In fact they might as well offer this as an option since a 40kW battery already is. It'd probably need to be 2-motor AWD though, with that much torque...
Homer Simpson - In This House We Obey The Laws of Thermodynamics - YouTube
No matter how you wire up the pack, each cell is going to see the same current for a given power draw.
Way you can make a crazy supercar version battery pack:
1. Allow for higher power draw from the pack and accept the drawbacks associated with that (in fact Tesla already does this with the 40 and 60 kWh packs and compensates by reducing the warranty terms for those packs).
2. Add more cells to the pack so each cell sees less current. Of course, this adds weight which reduces performance gain.
3. Replace current high-energy cells with high-power cells which can handle more power without issue. Drawback is that these cells can typically hold less energy so range will be reduced.
Back to the great pics Phil posted:
Interesting that they use such a small wire to carry the current from each cell. It looks to be no more than 26ga wire or similar? With over 7000 cells in the pack and a peak power draw of 310 kW, each cell is responsible for about 45W under peak load. With a lithium-cobalt cell having a nominal voltage around 3.7V, that's about 12A per cell over that tiny wire. Sure the wire is short, but I still have to wonder how much power is lost in each one under heavy load... I'm sure one of you EE guys will be able to calculate this quickly.
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Well, no. You can also think of it this way. 2 cells in parallel give you twice the capacity because the current is now half thru each--voltage & power staying the same. Perhaps you're thinking of capacity, which doesn't change no matter how you wire the cells (obviously)
(Though higher currents will effectively lower capacity because of higher power losses thru heat).
Well, no. You can also think of it this way. 2 cells in parallel give you twice the capacity because the current is now half thru each--voltage & power staying the same. Perhaps you're thinking of capacity, which doesn't change no matter how you wire the cells (obviously)
Well moving batteries from series to parallel will double you current (I), it will also half your voltage(V), and give you no power (P) gains. And P=IV shows this. half V and Double I and you get the same P.
Well it comes down to how the battery is wired. We know it's not purely a series or parallel arrangement of cells because I don't know what the final voltage of the battery pack is, but I'm pretty sure it's neither ~4V nor ~28,000V (assuming 7000 cells). So it's a mixture of both arrangements. To get more current handling, you just move to more parallel groups. Or think of it this way: assuming the 40kw packs are half the size, just wire two of those side by side in parallel. Well you can do that internally with an 85kw pack.
Correct. You cannot "wire differently" to be able to get higher discharge rate without reducing voltage.
Switch cells to ones who allow higher discharge rate is your answer, with different cell chemistry.
Since Tesla seems able to make very powerful motors/inverter combinations, and the battery pack output power is apparently the limiting factor, there is still hope someday that they could put an "ultracap front end" to provide bursts of high power for quick passing and 0-60 "hole shots", and then have the lithium-cells recharge the ultracap buffer at a more cell friendly rate.
It would be nice if the 40kWh Model S had the same 0-60 performance as the 85kWh versions...
It would be nice if the 40kWh Model S had the same 0-60 performance as the 85kWh versions...
You could also use the ultracap for regen braking- thus prolonging the battery life, and giving better regen performance on really cold days.
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Actually how do we know for sure there isn't some kind of ultra capacitor inside there already? I've heard Elon Musk often talk about how ultra capacitors may one day be good enough to replace the battery entirely. So I think we can safely assume that Tesla has carefully researched and considered all the angles for use of that technology in the current production Model S... (that doesn't of course mean there is one in there-- they probably would talk about it more if it was... on the other hand, they keep so much stuff secret...)
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Actually how do we know for sure there isn't some kind of ultra capacitor inside there already? I've heard Elon Musk often talk about how ultra capacitors may one day be good enough to replace the battery entirely. So I think we can safely assume that Tesla has carefully researched and considered all the angles for use of that technology in the current production Model S... (that doesn't of course mean there is one in there-- they probably would talk about it more if it was... on the other hand, they keep so much stuff secret...)
Todd Burch
14-Year Member
The major difference being that Tesla's existence is fragile at this point, whereas Apple is worth hundreds of billions of dollars.
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