To advertise 691HP, you only need to achieve it at one point in an engine RPM band. If you take an ICE car and have only one gear, you hit its peak at only one speed. You've still satisfied the advertised HP, so long as you hit it at some point along the way. So, I don't see the argument about 50 to 70, as much as I do the peak.
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[updated with *] P85D 691HP should have an asterisk * next to it.. "Up to 691HP"
- Thread starter krisg81
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- Driving Dynamics Model S
To advertise 691HP, you only need to achieve it at one point in an engine RPM band. If you take an ICE car and have only one gear, you hit its peak at only one speed. You've still satisfied the advertised HP, so long as you hit it at some point along the way. So, I don't see the argument about 50 to 70, as much as I do the peak.
ERP
Ludicrous Member
If the P85D hit a peak motor power of 691 hp this thread would not exist. So far there has not been any proof that combined hp is possible. Look at the graph below (taken from the previous page); between 30 and 75 mph the hp output is nearly flat. It tapers with rpm as expected, but it is not a steep decline. But the output is only 450-400 whp. If the motors were actually outputting 691 peak hp then tapering off, this section of the graph would be much higher and (30) 50-70 mph acceleration would be quicker.
I'd still be grabbing 4th gear, at 130mph on a race course, if I wasn't fully comfortable with the fact that electric cars show their best colors, at lower speeds with a full charge. All electric cars see fading roll-on performance as they wind out a single gear, and loose charge. Just because you can take a P85D and drain its battery down to 50% SOC, against, for all I know, a pre-warmed, fully charged 85D, and still lose in roll-on, doesn't say whole lot.
Voltage drops with discharge. Maybe we should revisit how batteries work? Fresh batteries mean brighter bike lights, better fidelity on your portable, or (much) faster RC cars and helicopters. You'll notice performance and voltage both go down throughout a charge. Same for a Tesla, and in this regard it seems many are complaining about what is really just an education. A couple tenths slower roll-on, because of voltage, is the same nitpick as if ICE were new and we complained about winding out 4th gear, in a car before 5, or 6, speeds. It really doesn't have much to do with substantially missing the peak claim, or for that matter, the way power falls off as you turn the P85D's steering wheel.
llavalle
Member
I think you misunderstood my point here. Both car had been charged to 90%... Then we followed each other for close to 200miles (road trip). I'm not saying that the drop in power is a problem, I understand the math behind it... I'm just saying when you compare the real life performance of a P85D vs a 85D, the difference gets smaller and smaller as SOC% (of BOTH cars) gets down.
Example (bogus numbers)
Both cars at 100%SOC : P85D is 30% faster 0-60 and 15% faster 60-80
Both cars at 60%SOC : P85D is 25% faster 0-60 and 10% faster 60-80
Both cars at 40%SOC : P85D is 20% faster 0-60 and 5% faster 60-80
Again, these are bogus number, just to illustrate what I think we are seeing here.
You get what I mean? While both car gets slower along with SOC, as expected (100%normal), the P85D loose its margin, especially at higher speed. Speculating here but I guess the new smaller drive units have a less pronounced HP drop as RPM ramps up.
That's what I meant. In any cases, 0-30 of the P85D totally destroys a 85D, event if the P85D is 30% and the 85D is 100%... but then, in that case, it's more of having more power where it matters most at those speed : on the rear axle. I can feel my front tires slipping under heavy acceleration. The P85D I tried did not do that, probably because the rear motor has more power and so is able to "push" the car as much as the smaller motor up front is "pulling" it.
Ah, got it. Watching all the PHEVs hitting the market, I've always thought folks under-weight the top end abilities of larger EV batteries, instead obsessing about range. So, I'm not too surprised that two 85kwh batteries are only going to be separated by so much. What I do find, though, if we are talking about perception, the visceral difference between P85D 0-30 and 85D 0-30, where P85D definitely loses more ability to accelerate as higher speeds come along. The acceleration goes down a steeper slope, no matter the resulting roll-on times we could gather. If you're both at the same SOC% and stepping on it, than yeah, perhaps the PD is simply programmed to grab less battery discharge. At 50%, I'd be bordering on a long trip. So, that isn't an around town SOC% for most owners, anyway.
I think one of the battery threads talks about 1.7C discharge (18650) as being a possible safe bound, that Tesla hasn't come close to using. The allowable C-rate probably goes down with voltage, too. I'd also wonder if the effects of the larger rear motor mass don't come into play, as falling V meets higher inertia?
llavalle
Member
Yep... I wonder if the patent may be of help here... See CONTROL SYSTEM FOR AN ALL-WHEEL DRIVE ELECTRIC VEHICLE - diagram, schematic, and image 02
In Fig 2, they call the 201 line the "primary motor" and the 203 line the "assist motor". While they do not represent actual rear and front motor of a P85D, you can clearly see that their "assist motor" has a very flat torque curve, especially compared to the main motor.
Based on that, I don't think it's far fetched to imagine that if you have 2 of the assist-type motor in a car, you'll get less of a drop at higher RPM. I don't know enough about the actual design of the motors themselves (along with their accompanying inverter) but I do remember reading somewhere that a 85D can sustain it's top speed longer than a P85D. Now, reaching that top speed is slower on the 85D... but it won't get into "power limited mode" like the P85D does. This clearly shows that the new drive unit are probably more efficient, especially at high RPM. This also matches the RPM limits in the specification page of the manual (see page 150). 16K for the large motor, 18k for the smaller one.
This does not change the fact that the P85D is VERY impressive but lets just say that with all of this, I'll keep my 85D and I'm glad I saved the difference in $$$. Now, when a new, bigger pack (or with higher drain) is available, the "P" should be faster!
I am amazed if there is any auto manufacturer trying to sell their performance model without advertising the Horse Power. Tesla claim the P85D has 691HP because they want you to believe it can go 0-60 in 3.2sec and it will be thrill to drive as it accelerate all the way the top speed, simple as that.
So why would you think Tesla advertise 691 hp instead of the real 550 hp, and why they haven't respond to this question yet?
JohnSnowNW
Active Member
For the same reason ICE, at least in the US, doesn't advertise WHP. The larger numbers sound better...I mean what does it matter if the vehicle can produce a certain amount of HP at the crank, when it doesn't put it down on the road?
For the most part HP numbers are used for advertisement, at least with performance oriented vehicles, and my opinion is that real world performance is a better measure. Now people have brought up that the vehicle doesn't accelerate like they'd expect at certain speeds...which if fine. However, the Model S is never going to perform as you'd expect at higher speeds, if your experience is with ICE vehicles, due to the gearing. So, how much faster would the Model S be at higher speeds, with rated horsepower, but the same gearing? I don't know the answer to this, but I suspect we'd have a thread on here where people complained about it.
They don't advertise that any more. My pure speculation is that they got ahead of themselves and fully intended to provide an update that draws 515KW but that they ran into issues or are having second thoughts due to long term battery health. This is my belief because I want to give them the benefit of the doubt and not assume this was an intentional misrepresentation as a way to boost sales.
Not sure where you got the 1.7C number from. The P85D at 415kW already pulls almost 5C. I personally have tested discharging individual Model S 18650 cells as high as 7C (~80W from a single cell!). They definitely heat up quickly at such crazy loads, but they can certainly do it safely if they're not already warm. Tesla's thermal loop should be able to suck away most of that heat in a reasonable amount of time, but definitely not capable of continuous discharge near these levels for that reason and others.
From my testing, the cell level fuses in the pack can easily handle 6C continuously and up to about 8C before popping (super bad).
Details: Pics/Info: Inside the battery pack - Page 54
I must have confused it with max sustained charge rates, which are closer to this zone. The point is that the gap you point to, of up to 7C from 5C, is the place we might expect Tesla (or some tuner) to uncork the P85D further.
Dear Tesla fan
I have been following this thread for a while and I more than agree that there is confusion about the 691 hk and that it should have an asterik.
I have a question though and my apology in advance if this has been asked and answered before, but can any one of you confirm a lower performance in Insane mode after the Version 6.2 was installed. I am talking 3.7-3.8s (0-60 mph) instead of the initial 3.1-3.2s.
At least I cant get my car anywhere below 3.6 s. I am using Racelogic, flat road, warm battery, fully charged, 21" etc.
I got my car delivered in June so never tested Insane with version 6.0 or 6.1.
Thx in advance.
Torben_E
I have been following this thread for a while and I more than agree that there is confusion about the 691 hk and that it should have an asterik.
I have a question though and my apology in advance if this has been asked and answered before, but can any one of you confirm a lower performance in Insane mode after the Version 6.2 was installed. I am talking 3.7-3.8s (0-60 mph) instead of the initial 3.1-3.2s.
At least I cant get my car anywhere below 3.6 s. I am using Racelogic, flat road, warm battery, fully charged, 21" etc.
I got my car delivered in June so never tested Insane with version 6.0 or 6.1.
Thx in advance.
Torben_E
Andyw2100
Well-Known Member
You said Racelogic. They make lots of products. VBox, PBox or one of the many far pricier professional variants?
With a 65% SOC, I'm seeing 3.2 seconds with a 1 foot rollout or 3.5 seconds without. With 90% SOC, I'm seeing 3.1 seconds with a 1 ft rollout. 3.7 seconds is not good if your SOC was over 60%.
Also, if you're using the iPad app, it can be error prone and not actually report the correct times. To remove all confusion, upload the vbo file directly to vBox Verify
It will extract all the valid 0-60 runs and throw out the one that are invalid for whatever reason. The ipad app will still report 0-60 results for invalid entries. The website will tell you which ones are valid, invalid, and give you times for 0-60 using a 1 foot rollout and from a dead start.
Thx Sorka
I just borroved the Racerlogic this Sunday so i am still figuring out how it works and thx for the tips. The unit has two labels. PerformanceBox and Racelogic. Guess it is a PBox then.
Great to know your 0-60 mph times and that is with 6.2 SW rigth ? My build is .250
I will try the vBox Verify later today.
Br and again thx
Torben_E
I just borroved the Racerlogic this Sunday so i am still figuring out how it works and thx for the tips. The unit has two labels. PerformanceBox and Racelogic. Guess it is a PBox then.
Great to know your 0-60 mph times and that is with 6.2 SW rigth ? My build is .250
I will try the vBox Verify later today.
Br and again thx
Torben_E
mkspeedr
Member
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