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Hence why I suspect the V3 supercharging will only apply to next gen packs, as mentioned in my first post. I was speculating how tesla will increase the power beyond a mere 350KW. My guess is a lot higher voltage, instead of a lot more amps.
Remember, total power safely in to the pack is determined by the cell's C-rating which is determined by chemistry & construction.
Current Tesla NCA Li-ion cell packs (excluding 60's) accept a peak of about 400V & and ~330A. Or in the neighborhood of 1.5-1.7C, depending on pack size.
Assuming the Model 3 has a ~60Kw pack, that would mean @ 800V a 1C current draw of:
60,000/800V=75A
Assuming the same ~1.7C capability of the cells, the packs could draw ~127A or 100KW. Still less than current superchargers can deliver. Heck even assuming the new 2170's are capable of a 2C rating, that would only be 150A/60KW.. still less than current superchargers.
So increased voltage doesn't necessarily buy folks what they might think.
Here is my guess:
For current cells, they are very close to the C-rate limit. (tho I can't find any reference about actual limit)
120kW / 480V = 250A
250A / 74 = 3.4A (74 groups in parallel)
3.4A for each 3100mAh cell is ~1.1C.
The reasonable way to apply >350kW is:
1. increase the cooling ability on the car
2. raise the voltage of SC from 480V to 1000+V
For current cells, they are very close to the C-rate limit. (tho I can't find any reference about actual limit)
120kW / 480V = 250A
250A / 74 = 3.4A (74 groups in parallel)
3.4A for each 3100mAh cell is ~1.1C.
The reasonable way to apply >350kW is:
1. increase the cooling ability on the car
2. raise the voltage of SC from 480V to 1000+V
Look again. The maximum charging speed in kW is achieved at low SOC when the battery pack voltage is low. On the big battery packs (85/90/100) the low SOC voltage is around 355 VDC. The peak SuperCharger current is actually about 333 Amps. That is how you get the maximum SuperCharger power for current vehicles.
355 V * 333 A = 118kW
Anyway, the point I really came here to make was that 333 amps is a lot of current to push through the Tesla inlet. The more current you pass through a connector, the more heat can be generated. If they would double the pack voltage, they could halve the current for the same C-rate and would generate less heat in the cables and connection points. That would make SuperCharging more reliable. Given recent experience in California with reduced charging rates that seems to be correlated to charging handle overheating, this would be a significant improvement. They don't have to double it like other makers are talking about either. Moving the peak pack voltage up to about 480 VDC, just under the 500 VDC limit of other infrastructure like CHAdeMO chargers, would reduce the Supercharger current to 250 Amps. The difference in heat generation would be noticeable.
355 V * 333 A = 118kW
Anyway, the point I really came here to make was that 333 amps is a lot of current to push through the Tesla inlet. The more current you pass through a connector, the more heat can be generated. If they would double the pack voltage, they could halve the current for the same C-rate and would generate less heat in the cables and connection points. That would make SuperCharging more reliable. Given recent experience in California with reduced charging rates that seems to be correlated to charging handle overheating, this would be a significant improvement. They don't have to double it like other makers are talking about either. Moving the peak pack voltage up to about 480 VDC, just under the 500 VDC limit of other infrastructure like CHAdeMO chargers, would reduce the Supercharger current to 250 Amps. The difference in heat generation would be noticeable.
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Not sure why you guys need to calculate the amps for each cell. Maybe you don't trust tesla's battery capacity? If so I understand. But if not see the math below.
You get C by just looking at the energy capacity and power charge rate.
Here is simple math:
100KWh charging at 120KW.
This means 120KW/100KWh or 1.2C into individual cells.
So 350KW into a 100KWh battery means 3.5C into the individual cells.
No need to calculate the amps. Don't trust me? Just do the calculation you will come up with the same answer. Think of it as how many times of capacity you are putting into the battery. It will apply to ALL individual cells of the battery pack.
Now for the increase voltage argument. The voltage increase is so tesla doesn't need to redesign a contactor or thicker cable to carry the increase Amps. Without the higher voltage. You are looking at 875A through the contactor and cables both on the supercharger side as well as the cable that runs to the battery bypassing the AC charger. At 800V the current is at 437.5A which is much more reasonable for the current contactor and cable size.
You get C by just looking at the energy capacity and power charge rate.
Here is simple math:
100KWh charging at 120KW.
This means 120KW/100KWh or 1.2C into individual cells.
So 350KW into a 100KWh battery means 3.5C into the individual cells.
No need to calculate the amps. Don't trust me? Just do the calculation you will come up with the same answer. Think of it as how many times of capacity you are putting into the battery. It will apply to ALL individual cells of the battery pack.
Now for the increase voltage argument. The voltage increase is so tesla doesn't need to redesign a contactor or thicker cable to carry the increase Amps. Without the higher voltage. You are looking at 875A through the contactor and cables both on the supercharger side as well as the cable that runs to the battery bypassing the AC charger. At 800V the current is at 437.5A which is much more reasonable for the current contactor and cable size.
I
The max I have ever seen on my car is 290A.
I am not sure about the max 333A. Maybe the regular 85KWh battery is different. But on my tesla the fastest charge rate for me was when the car is about 385V or so. Attached is the specs on the supercharger V2.0 themselves.
The max I have ever seen on my car is 290A.
Attachments
Before I posted, I checked Bjorn's videos just to be sure. Just look at the first 30 seconds of the video below.
Yup.
But the title of this is regarding 350kW charging, and the OP asked: "... will the batteries in the current cars be able to handle the wattage?"
Certainly nobody is arguing that you couldn't reduce the current cable gauge with the higher voltage for the same power delivery. But many people mistakenly believe that simply increasing voltage allows the total power delivery to increase... and while that is possible for a given cable size, it's not necessarily the case for a given cell/pack rating.
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Absolutely.
For me it's more to illustrate the point, given there are now competing announcements from other folks using competing standards (CCS) advertising 350kw charging. However it's also believed that power is achieved with a 1000V rating, which no current, or announced, car is configured for.
As a result, that power is not practically achievable, and the math to determine the current draw figures out what is.
Heck, some of the current "150kW" chargers are in the same boat... they are rated at 500V which means the are really limited to less for current packs as a result of the current limitation they have.
So you are certainly right... not strictly true for talking about Superchargers... but useful for understanding the implications of what Tesla will need to do for higher power delivery levels.
Chuq
Active Member
Just noticed a new Electrek article about Supercharger v3 - not a lot of definite info, a bit of speculation about ZEV credits.
Tesla’s upcoming ‘Supercharger V3’ is the last piece of the EV adoption puzzle – and means more ZEV credits
[Edit: And insideevs.com - Elon Musk: Tesla Supercharger V3 Coming With Output Over 350 kW ]
Tesla’s upcoming ‘Supercharger V3’ is the last piece of the EV adoption puzzle – and means more ZEV credits
[Edit: And insideevs.com - Elon Musk: Tesla Supercharger V3 Coming With Output Over 350 kW ]
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If Tesla wanted the Model 3 to accept 350 kW of current, it can design the battery pack to do so, including chemistry or whatever else is needed. Nobody really knows what is going into the Model 3 pack. One of the reasons Tesla built the battery gigafactory was so it can manufacture what it wants and not be dependent on someone else.
True... within the bounds of today's battery technology constraints.
There are batteries that can indeed accept 6C charge rates. However they typically are deficient on some other performance axis critical to EV applications: energy density, cycle life, thermal stability, volumetric density, etc...
Tesla certainly could have more advanced chemistry/construction for it's next gen cells, but a jump bay a factor of ~4X for charge rates is pretty radical. I'd love to see it, but temper my expectations.
Electric700
Active Member
I don't think this is true. They may have to take each Supercharger center offline before they upgrade it though.
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I don't think there is much opportunity to earn more ZEV credits. More info here:
Will V3 Superchargers Provide More ZEV Credits and Revenue?
GSP
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