Newer P90DL makes 662 hp at the battery!!!

[St Charles]

Tesla has been talking about using new 2170 format batteries instead of the current 18650. They're only a little bigger in height and diameter so they might be able to pack them into the same foot print.

So yeah, those cells are larger but that extra space has to come from somewhere. It would be interesting to see a side by side teardown to see if the same number of cells are used with the new format.

 

[R.S]

All of tesla's packs to date have increased in power with increased capacity. And in going from 85kwh to 90kwh the increased current ratio was pretty close to the increase in capacity ratio.

The 85kwh battery is configured as 96 cells in series with 74 of these series connections in parallel. Each of those 74 provide 1/74th of the power out of the battery. Since the voltage has remained the same in going to 90kwh the capacity could be increased by using 78 in parallel. That would increase the packs power delivery by 78/74ths, the same as the capacity ratio. In any case since the voltage remains the same the only way to increase capacity is to increase amp-hrs. Typically, you can pull more amps as the amp-hr rating goes up, using similar chemisty.

If you start at the foot of a mountain and you go up path, will the path go up forever, since it did so for the lat few hundred steps?
While I still do think it will increase in power, your explanation makes no sense at all.

If there are 74 in parallel, they provide a 74th of the amperage, not the power. Every cell provides 1/7104th of the power, no matter if they are all in series, or all parallel. The power, or the internal losses don't even change, if we just look at the batteries, if we switch from all parallel to all series. And why should the 90kWh pack should use more cells parallel. The voltage would drop if they did that. I guess the cells still have the same voltage, but a higher capacity. And the notion that you can pull more amps out of a higher amp hour cell is just wrong. It is true if you have a bigger cell, or look at a pack with more cells in it, but other than that its just wrong.

It would be nice if we could solve all our battery problems with fractions, 7/12, 18/4, 99/263... but it really isn't that easy.

 

[TIppy]

If you start at the foot of a mountain and you go up path, will the path go up forever, since it did so for the lat few hundred steps?
While I still do think it will increase in power, your explanation makes no sense at all.

If there are 74 in parallel, they provide a 74th of the amperage, not the power. Every cell provides 1/7104th of the power, no matter if they are all in series, or all parallel. The power, or the internal losses don't even change, if we just look at the batteries, if we switch from all parallel to all series. And why should the 90kWh pack should use more cells parallel. The voltage would drop if they did that. I guess the cells still have the same voltage, but a higher capacity. And the notion that you can pull more amps out of a higher amp hour cell is just wrong. It is true if you have a bigger cell, or look at a pack with more cells in it, but other than that its just wrong.

It would be nice if we could solve all our battery problems with fractions, 7/12, 18/4, 99/263... but it really isn't that easy.

If they provide 1/74 the amps and they all have the same voltage across them they provide 1/74 the power. p = v x i = v x i1 + v x i2 + v x i3 + ... v * i74 = v x (1i + i2 + i3 + ... + i74). If there are 74 of them in parallel and 1500 amps are being drawn, then each one is providing 1500 / 74 = 20.3 amps. The 94 cells in series are providing 305 volts under this load, so are providing 305 * 20.3 = 6182 watts. But there are 74 of this units working in parallel, so 74 * 6182 = 457500 watts. If there are 74 identical arrangements of cells in parallel, why would any one provide any more or less power than its neighbor; they all provide the same amount of power. Each additional string of 96 cells in series would be able to provide an additional 20.3 amps at 305 volts..

 

[TIppy]

And the notion that you can pull more amps out of a higher amp hour cell is just wrong. It is true if you have a bigger cell, or look at a pack with more cells in it, but other than that its just wrong.

The charge and discharge current of these cells is specified as some fraction of C, the amp-hr capacity of the cell. Like 1C charging current, 2C discharge and 7C discharge for 10 seconds. It seems odd that they would specify current handling capability as a function of some variable, C, that had nothing to do with current capacity.

 

[St Charles]

The charge and discharge current of these cells is specified as some fraction of C, the amp-hr capacity of the cell. Like 1C charging current, 2C discharge and 7C discharge for 10 seconds. It seems odd that they would specify current handling capability as a function of some variable, C, that had nothing to do with current capacity.

This is a very common way to express charge/discharge capability of Lithium batteries. I believe it has to do with the internal resistance of the cell.

 

[TIppy]

This is a very common way to express charge/discharge capability of Lithium batteries. I believe it has to do with the internal resistance of the cell.

At a given voltage, say 305, the lower the internal resistance, the more current you get. So the implication is that the higher the amp-hr rating, C, the lower the internal resistance. When I said it was odd, I was being sarcastic in response to R.S. who said the notion that current would increase with increasing amp-hrs was wrong.

 

[St Charles]

At a given voltage, say 305, the lower the internal resistance, the more current you get. So the implication is that the higher the amp-hr rating, C, the lower the internal resistance. When I said it was odd, I was being sarcastic in response to R.S. who said the notion that current would increase with increasing amp-hrs was wrong.

I like to think I was adding to your comments

 

[TIppy]

I like to think I was adding to your comments

Thanks.

 

[R.S]

The charge and discharge current of these cells is specified as some fraction of C, the amp-hr capacity of the cell. Like 1C charging current, 2C discharge and 7C discharge for 10 seconds. It seems odd that they would specify current handling capability as a function of some variable, C, that had nothing to do with current capacity.

That C rate is just very practical, when it comes to charging. you know how long your cell has to charge. And its a good relation between capacity and power, but still it isn't a fact that higher capacity cells have more power. Just look at li-polymer cells, the don't have the highest capacity, but very high power densities. There just isn't a correlation between capacity and power.

 

[TIppy]

That C rate is just very practical, when it comes to charging. you know how long your cell has to charge. And its a good relation between capacity and power, but still it isn't a fact that higher capacity cells have more power. Just look at li-polymer cells, the don't have the highest capacity, but very high power densities. There just isn't a correlation between capacity and power.

We're speculating on what tesla is going to do. They're not likely to change to some new battery technology in the near term. In cells that are very similar, there seems to be a strong correlation between amp-hrs and current capacity. If not, why specify 1C or 2C? Why not discharge current should be limited to two times the diameter or length of the cell? It seems C must have some significance in determining how much current you can safely draw from the battery.

 

[TIppy]

The Panasonic NCR18560 and NCR18650B are both the same size cell. The B variant is 3200 mah and the other is 2700 mah. On the "Discharge characteristics(by temperature)" plot for each of these cells, Panasonic plots the voltage of the cell vs mah consumed. On the plots for both batteries the constant current being drawn is specified as 1C, so for the B variant that's 3.2 amps and 2.7 amps for the other. Using the highest temperature plot which is 104 degrees F, not quite to the 112 degrees for max battery, both plots indicate 4.0 volts at 0 mah consumed. Even though the B variant is supplying about 20% more current, the output voltage is the same as the non-B variant. That's a pretty good indication that the B variant has lower internal resistance. By the time both batteries have provided 1500mah, they still have equal voltages of 3.5volts.

 

[St Charles]

There just isn't a correlation between capacity and power.

Sure there is. Given that battery cell chemistry is unchanged then an increase in capacity should allow for a larger amperage draw from the battery pack.

As capacity increases in a pack of batteries it becomes possible to pull higher overall amperage at a given voltage. More amps at the same voltage means more power. This concept is expressed in the variable C. In words, 1C is the number of continuous amps at the rated voltage supplied from a battery for 1 hr. The C rating of a battery pack is how many C can be drawn safely from a battery. I have an RC car that runs on an 11.1v battery pack, rated at 50C. This means that I can safely draw up to 50x the rated capacity of the battery pack for a short time.

Lets bring this to Tesla:
I have a 90kWh, 400V pack. This means I can draw a continuous 225A for an hour before my pack becomes discharged (90,000w / 400V = 225A). Now, lets add in the maximum amperage drawn as measured, 1600A. This would mean that Tesla has determined that the maximum C rating of my battery pack is 7.1C.

Lets assume that the 100kWh pack comes out and it is also rated at 400V. 1C on this battery would be 250A (100,000w / 400v = 250A). Now, if we assume that the C rating of the new pack is the same (7.1C) then we can multiply 250A x 7.1C and arrive at a maximum theoretical safe draw of 1775A.

More on C rating:
Charles-Augustin de Coulomb's C-Rate for Batteries

 

[ggnykk]

The Panasonic NCR18560 and NCR18650B are both the same size cell. The B variant is 3200 mah and the other is 2700 mah. On the "Discharge characteristics(by temperature)" plot for each of these cells, Panasonic plots the voltage of the cell vs mah consumed. On the plots for both batteries the constant current being drawn is specified as 1C, so for the B variant that's 3.2 amps and 2.7 amps for the other. Using the highest temperature plot which is 104 degrees F, not quite to the 112 degrees for max battery, both plots indicate 4.0 volts at 0 mah consumed. Even though the B variant is supplying about 20% more current, the output voltage is the same as the non-B variant. That's a pretty good indication that the B variant has lower internal resistance. By the time both batteries have provided 1500mah, they still have equal voltages of 3.5volts.

So the latest Model S/X are using the 3200 or 2700 mah? If it is still using 2700 mah, that means the battery capacity will go well beyond 90 kwh while keeping the battery in the same dimension?

 

[TIppy]

There just isn't a correlation between capacity and power.

In my previous post(#1151), I gave the concrete example of the NCR18650B with its 20% higher capacity being able to draw 20% more current for the same voltage drop. That's because the higher capacity cell has lower internal resistance. The lower the internal resistance a cell has the higher the power it can deliver to a load. At a given current there is more voltage available at the battery terminal, less power dissipated inside the cell. Max power is delivered when the resistance of the load equals the internal resistance. So the increased capacity has allowed for more power, thus there is a correlation.

 

[lolachampcar]

It is a good bet that Tesla is introducing battery construction/chemistry changes as fast as they can perfect/test/prove them. This is their MO with S and there is no reason to believe they are not evolving their batteries at least as fast and implementing the changes/improvements just like they do with their vehicles.

 

[TIppy]

So the latest Model S/X are using the 3200 or 2700 mah? If it is still using 2700 mah, that means the battery capacity will go well beyond 90 kwh while keeping the battery in the same dimension?

Probably neither. It's my understanding that Panasonic provides a tesla specific cell. But in the 85Kw pack there are 7104 cells, so each cell provides 85000 / 7104 = 11.97 watt-hrs. At an average discharge voltage of 3.6v, that gives 11.97 / 3.6 = 3.324 amp-hrs or 3324 mah. So they're already the big boys.

 

[Mickie]

Anyone else notice the Model S and Model X P90D Ludicrous Mode upgrade pages have added the same disclaimer text as the P85D Ludicrous Mode upgrade page? Specifically "The retrofit will not be an exact equivalent performance spec as a new P90D." Previously only the P85D Ludicrous Mode upgrade page had this disclaimer. The plot thickens...

Tesla — Ludicrous Mode P90D
Tesla — Ludicrous Mode P90D
Tesla — LUDICROUS MODE ONLY (P85D) - PRE ORDER DEPOSIT

Yeah so, about this. Is this a copy paste mistake from the P85D page's help text, or is it confirmed a factory P90DL is going to perform slightly better than a P90D that was retrofitted with ludicrous?

 

[TIppy]

Yeah so, about this. Is this a copy paste mistake from the P85D page's help text, or is it confirmed a factory P90DL is going to perform slightly better than a P90D that was retrofitted with ludicrous?

I don't know how else to read that. I guess it could be in error. But it kind of aligns with the up thread discussion of the newer P90D packs having a different part number than the earlier ones. Something about the newer part numbered pack shouldn't be used on cars built earlier than April 2016.

 

[fiksegts]

best 1/8 mile, MPH and 60' to date:

6.8 @ 100.7 MPH....

2016 Tesla Model S P90DL v2 1/4 Mile Drag Racing

this car will go 10's....

 

[St Charles]

best 1/8 mile, MPH and 60' to date:

6.8 @ 100.7 MPH....

2016 Tesla Model S P90DL v2 1/4 Mile Drag Racing

this car will go 10's....

True story! If I could get a 1.55 60' i'm pretty sure that I could get a 10.9 with my rig.