The effect of passing on range....

[David_Cary]

Let's add some data to the conversation. I love the fact that we can do that with a Tesla.
Now sadly I don't have a P85 so I don't have the data to offer that you are exactly looking for, but maybe this helps anyway. This is from a recent drive with my S60. I was passing very aggressively, let's assume for this post that I was driving somewhere with a speed limit of 100mph... :redface:
The first graph shows the complete passing in context, the second one zooms in on just the accel / regen part (back to the original speed - it turns out I slowed down even more than that if you look closely).
So I spent 558Wh to pass (but bear in mind that I would have also spent some energy to maintain speed) and recovered 322Wh in regen. So I used 236Wh to pass - and I'm estimating that it would have taken me about 168Wh to just keep my speed (this is simply by using the 28 seconds prior to passing as benchmark). So total cost of a very spirited passing maneuver? About 68Wh. Or 3/4 of a cent at my electricity cost
Again, all this is with an S60. The P85 can use quite a bit more power (but then would only need to use it for a shorter period of time, right?) - my guess is the number for a P85 would be very comparable. If a P85 driver who is using teslams into a mongoDB to track their telemetry data is willing to do the comparable graphs I'd love to help (this analysis hasn't landed in Hans' github repository just yet... I wrote the code a minute ago in order to be able to respond here... thanks for giving me an idea what else we could do with these graphs

I have to think something is amiss with this scenario. What it looks like you didn't account for is the fact you went further in that 28 secs and you experienced a greater drag because of higher speeds. Taking those into account, I got 6 Wh wasted which is not possible because the transfer of electricity to kinetic energy is just not that efficient. I used 80 mph for average speed in the 28 secs amounting to .15 extra mile covered and then a used a 15% aero penalty.

Am I missing something ... Like a big hill?
.

 

[Alpha]

Yes, air drag is your enemy - most of the energy used goes into overcoming that.
But other accounts have shown that the regen really is quite efficient at recouping a lot of the energy.
For example:
Drag Times: Six Cents To Drag Race Your Tesla Model S (w/video)

 

[dirkhh]

Let's add some data to the conversation. I love the fact that we can do that with a Tesla.
Now sadly I don't have a P85 so I don't have the data to offer that you are exactly looking for, but maybe this helps anyway. This is from a recent drive with my S60. I was passing very aggressively, let's assume for this post that I was driving somewhere with a speed limit of 100mph... :redface:
The first graph shows the complete passing in context, the second one zooms in on just the accel / regen part (back to the original speed - it turns out I slowed down even more than that if you look closely).
So I spent 558Wh to pass (but bear in mind that I would have also spent some energy to maintain speed) and recovered 322Wh in regen. So I used 236Wh to pass - and I'm estimating that it would have taken me about 168Wh to just keep my speed (this is simply by using the 28 seconds prior to passing as benchmark). So total cost of a very spirited passing maneuver? About 68Wh. Or 3/4 of a cent at my electricity cost
Again, all this is with an S60. The P85 can use quite a bit more power (but then would only need to use it for a shorter period of time, right?) - my guess is the number for a P85 would be very comparable. If a P85 driver who is using teslams into a mongoDB to track their telemetry data is willing to do the comparable graphs I'd love to help (this analysis hasn't landed in Hans' github repository just yet... I wrote the code a minute ago in order to be able to respond here... thanks for giving me an idea what else we could do with these graphs

I have to think something is amiss with this scenario. What it looks like you didn't account for is the fact you went further in that 28 secs and you experienced a greater drag because of higher speeds. Taking those into account, I got 6 Wh wasted which is not possible because the transfer of electricity to kinetic energy is just not that efficient. I used 80 mph for average speed in the 28 secs amounting to .15 extra mile covered and then a used a 15% aero penalty.

Am I missing something ... Like a big hill?
.

a) your post will look better if you add the missing "[/" QUOTE "]" (you can always go back and edit it...)
b) don't know about your assumptions. My post is based on data straight from the car. There wasn't a significant hill (even though this was a hilly trip). Maybe a slight downhill.

 

[David_Cary]

Thanks for the quote help - I seem to mess that up a lot.

The drag race recovers about 50% of the energy but the car travels a distance - 1 mile? (1/4 mile + decel). It gets that mile for 500 Wh or a bit more than an average mile. But 500 Wh is pretty good. What seems hard to believe is that when you plug in all the loses, 1 got 6 Wh wasted which 1% of the acceleration. Regen is certainly not 99% efficient. On other EVs (and I see no reason to think Tesla is different), even 80% is probably optimistic.

 

[dirkhh]

Thanks for the quote help - I seem to mess that up a lot.

The drag race recovers about 50% of the energy but the car travels a distance - 1 mile? (1/4 mile + decel). It gets that mile for 500 Wh or a bit more than an average mile. But 500 Wh is pretty good. What seems hard to believe is that when you plug in all the loses, 1 got 6 Wh wasted which 1% of the acceleration. Regen is certainly not 99% efficient. On other EVs (and I see no reason to think Tesla is different), even 80% is probably optimistic.

Totally agree - 99% seems outrageous. But I am wondering how exact your estimates of the added distance / added drag are. Also, it's possible that my sample length isn't perfect (i.e., that I ended up slower than I started), which also helps explain the effect.

 

[David_Cary]

I estimated 15% lower efficiency due to aero effects - figured average speed was close to 80 and even a very aerodynamic car should lose 15% between 60 and 80. Using that average speed, I figured you traveled .16 mile further than you would have - 30 sec at 80 instead of 60. Sure - estimates.