Performance Battery worth $5k?

[PanameraFrank]

no EV owner ever said “I have too much range”

Just to piggyback on this, the other way to think of the PB+ is as an investment in the future.

A) You might suddenly need more range one day
B) EV Batteries degrade and you will lose range over the life of the car.

$5k for 14 more kWh is well, well, well worth it IMHO and you will never go "oh no I have too much range!" but you might go "oh no I don't have enough!"

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[f1eng]

So perhaps one of our engineers can help me better understand the relationship between torque and horsepower. My understanding is that if you have two engines with the same torque but one with more horsepower, the one with more horsepower will be able to apply that torque in a shorter period of time(note: faster rotation?).

Power is torque times speed so we use the torque curve is to calculate the power curve, since power is what gives the performance.

The thrust at the tyre is indeed torque multiplied by gear ratio and wheel radius but the important thing is that there is this gear ratio in there.
As an illustration imagine two engines with the same max torque but one of them achieves this torque at twice the RPM. That means that the this engine actually has twice the power of the other and will require twice lower gearing for the same car speed which will give twice the thrust at the tyre contact.

That doesn't mean"ease of drivability without changing gear" which many people falsely refer to as "torque".

Edit:
The torque varies with motor speed too, not as peaky as an IC engine but the torque curve, which defines the power, is not flat.

 

[gnop1950]

Just to piggyback on this, the other way to think of the PB+ is as an investment in the future.

A) You might suddenly need more range one day
B) EV Batteries degrade and you will lose range over the life of the car.

$5k for 14 more kWh is well, well, well worth it IMHO and you will never go "oh no I have too much range!" but you might go "oh no I don't have enough!"

I agree, and at these price points, unless you are in a real money crunch, I'm very much in the no regrets mode of purchasing. I find I regret cutting corners much more often than I regret adding an option.

 

[jasperp]

The question about additional acceleration power is answered in the thread "RWD Power/Weight vs Accel Anomoly" by Macad80.
Please read that if you want to know the details.

Conclusion:
With launch control both are equally fast 0-60.
Without launch control PB is faster from the line. Mid range they are equally fast. At high speeds PB+ is faster.
The reason is that PB+ is more heavy, with equal torque and more power.

 

[smohr33]

The question about additional acceleration power is answered in the thread "RWD Power/Weight vs Accel Anomoly" by Macad80.
Please read that if you want to know the details.

Conclusion:
With launch control both are equally fast 0-60.
Without launch control PB is faster from the line. Mid range they are equally fast. At high speeds PB+ is faster.
The reason is that PB+ is more heavy, with equal torque and more power.

Again, just conjuncture without real world results.

Until someone has a slip from a regular battery car, we know nothing.

 

[JimBob]

You can start here

 

[jasperp]

B) EV Batteries degrade and you will lose range over the life of the car.

I agree that anticipating for battery degradation is a good argument.
(unlike acceleration and resale value)

 

[jasperp]

Again, just conjuncture without real world results.

Until someone has a slip from a regular battery car, we know nothing.

The numbers are quite clear already. The torque is equal. The PB+ is more heavy. That are facts.

I expect the difference to be too small to reliably measure it. Other things like battery state and temperature will affect the measurement. You will need to do a drag race.
It would indeed be nice to see it proven in reality.
A nice 'science project'

But I am sure the difference will be too small to be relevant in practice.

 

[gnop1950]

The numbers are quite clear already. The torque is equal. The PB+ is more heavy. That are facts.

I expect the difference to be too small to reliably measure it. Other things like battery state and temperature will affect the measurement. You will need to do a drag race.
It would indeed be nice to see it proven in reality.
A nice 'science project'

But I am sure the difference will be too small to be relevant in practice.

The difference would likely be small, but with the better power-to-weight ratio of the PB+ 10.1 versus 11.4 and the greater HP (and Torque in launch control). I'm betting on the PB+.

Now, if we can just get someone to buy two identical RWD Taycans with the only difference being the PB/PB+ and run a bunch of drag races for us we can settle this once and for all. Any volunteers?

 

[gnop1950]

Yup, but YOLO ? A friend offered to sell me his Model 3, I think he was looking to upgrade to a Model S. I took a look, but it had absolutely no appeal to me. By the time I finished optioning my 4S I could have bought 2 M3P's and a new motorcycle. But, I wanted a Porsche. Originally I was looking at 911's but then a Taycan caught my eye and the rest is history. Future history since my 4S started production on the 25th of this month and is scheduled for delivery the first week in April.

A lot depends on your circumstances. My Porsche is my retirement gift, encouraged by my family. I should note that this is my first EV and if Porsche wasn't making the Taycan my new car would have been a 911 (not a different EV).

 

[jasperp]

The difference would likely be small, but with the better power-to-weight ratio of the PB+ 10.1 versus 11.4 and the greater HP (and Torque in launch control). I'm betting on the PB+.

If you really care about such little performance differences, you have to start thinking about the additional weight of the air suspension, the rear wheel steering, the better audio system, the glass roof,...
It all adds weight and can also add 0,1 seconds of acceleration time.

 

[gnop1950]

If you really care about such little performance differences, you have to start thinking about the additional weight of the air suspension, the rear wheel steering, the better audio system, the glass roof,...
It all adds weight and can also add 0,1 seconds of acceleration time.

The question was are the differences between the PB and PB+, performance, capacity, resale value, range, etc, worth the extra cost. Whether or not it is worth the extra money is an individual decision. For example, I opted to not get the glass roof. Not to save money or weight, I just personally don't like glass roofs.

In my opinion, the sum of the differences between the PB and PB+, even though each individual difference like speed may be minimal, is worth the extra cost. Everyone will have to make their own decision on what is important to them.

P.S. And I doubt I'll be doing much drag racing. Certainly not when my wife is in the car

 

[Marcad80]

Conclusion:
With launch control both are equally fast 0-60.
Without launch control PB is faster from the line. Mid range they are equally fast. At high speeds PB+ is faster.
The reason is that PB+ is more heavy, with equal torque and more power.

This is correct, for those who want to dive a little deeper into the Engineering see below:

The PB+ battery has a higher voltage than the PB battery (more batteries in series. And for those that want to know the Taycan has 2 bundles of series batteries wired in parallel. 4.2v batteries x 396 = 1663 volts so two parallel strings are 831v)

So if the PB+ cars motor would maintain the same current (I) as the PB car it would have a higher power P because the Voltage V is greater with the larger batter (P=V*I). All DC so it works out really nicely.

Therefore, since the Torques are equal they are actually current limiting the PB+ to a lower current than the PB to hold the same HP at a given RPM (HP=Torque * RPM). This is very sad, since current defines the heat generated and proving through the PB that a higher current level is acceptable. That means this is intentional.

Also the only reason the PB+ even shows a higher HP is because at higher speeds (I estimate above 50mph) the PB’s current reaches the real system current limit before the PB+ does because of its lower Voltage. Again P=V*I. So when the PB+ reaches the same current as the PB it’s now actually at a higher rpm, and therefore a higher HP. Again HP=Torque x rpm.

But since I don’t plan on racing a lot of people from 50mph to 100mph, this is a useless range for me and the equal HP from 0-50 of the PB and PB+ minus the additional weight I’m carrying for the batteries, makes this a slower accelerating car to 50 (my estimated crossover point).

For reference, if they did run the same current mapping between the cars (which they should have) the RWD PB+ would be in the range of 4.6 sec 0-60.

But I do need the range, so PB+ it is for me.

a little about me. I spent 20 years as an automotive engineer, and am currently an Engineering Fellow in the Aerospace industry. I used to design steering systems and my last two in automotive were the Cadillac CTS and BMW Z3.

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