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Laurent
Member
smorgasbord
Active Member
Let's be careful with the round-offs. The original poster asked about 68mpg, not 75mph. The Roadster graph shows about 77% for 68mpg versus 55mph. With the better aerodynamics of the Model S, that figure may be different.
With the QC being advertised as 50% charge in half-hour, you can't double that time to get a full charge. Charging needs to slow down as the pack fills.
Finally, I started a thread about this, but no-one's taken the time to do it the way I asked, is that by driving slower you may actually reach your destination sooner since you reduce necessary charge time. Maybe I'll use some time over the holidays to finally crank out the spreadsheet, but if your destination is 275 miles away you'll get there faster at 55mph than to drive at 75mph and have to stop for a charge (even a quick one). Once the trip is longer than your range at safe highway speeds, however, there's some math involved.
WhiteKnight
_____ P85 #549 _____ Sig Red / Sig White
It has been there, just hidden. Kind of like the Signature information hiding off to the side.
That makes about 650 miles in 12 hours. That is a full days driving IMO. Or 450 miles in 8 hours.
strider
Active Member
Yeah, this Sig premium thing is bugging me too.
I'm looking at the Sport model. I don't need the twin chargers or the parcel shelf but I do want the pano roof, tech package, pearl white paint, and sound system upgrade). So I'm looking at a $6,800 premium to go Sig. That seems like a lot of extra dough to me.
I'm looking at the Sport model. I don't need the twin chargers or the parcel shelf but I do want the pano roof, tech package, pearl white paint, and sound system upgrade). So I'm looking at a $6,800 premium to go Sig. That seems like a lot of extra dough to me.
goyogi
Member
Though another way to look at it is you have the 'frunk' to hide your goods. The back area is your choice of child seats or extra storage to be hidden by the cover.
Kipernicus
Model S Res#P1440
Except it's really not an option to drive 55 on any highway. Even going the speed limit you risk many a honk and "the look".
I would like to drive from the Bay Area to Sacramento, about 120 miles (with a sizeable hill in the middle). While the 40kWh pack might make it, there would be no margin for error. I will either stretch $10k for the 60 or just not drive the S to Sacramento.
Yea, I really don't think the 160 is meant for trips. It's better than the leaf, but it's really meant for someone that does a lot of city driving. A real estate agent for example. Or someone with a set commute distance, something like 40-50 miles each way. Even with a charging infrastructure, it'd have to be extremely regularly spaced at every 75-100 miles or so. You couldn't afford to miss a charge point if the next one isn't for another 100 miles.
Yeah. You want to enjoy yourself on the drive. Worrying if you'll make it there especially in a few years when the range starts to decrease isn't worth it. Plus getting the 60 kWh pack brings you a few other benefits. I'd do it if possible.
That is absolutely true for the Roadster. If your miles per hour while driving is much higher than your miles per hour while charging, it will definitely help if you drive slower.
The only restriction is that you can't safely drive at an arbitrary speed. I wouldn't want to drive slower than 105 kph on the 401. You would have to take a slower highway if you wanted to drive slower than that.
stopcrazypp
Well-Known Member
That's the same trip I make too (and why a Leaf absolutely won't work for me). You can drive between 55mph-65mph in the slow lane and not have many issues. People can just pass you if they are in a hurry (I usually drive when there is little traffic so that's not an issue). I typically drive 65-70mph in the middle lane and have never been honked at. No need to go 75mph.
The 160 mile pack doesn't leave much margin for error though (esp. if you drive it in normal mode). If possible I'll wait until the EPA rating is out as that'll give a pretty good idea of what you can expect, even driving at the speed limit. A rough estimate is 112 miles (160 * 70%).
If I have time, I'll edit the Roadster graph and update it with the latest consumption data given by Straubel in a recent presentation (which I assume is consumption data from the Model S).
Awesome. Thanks. At least there is one reasonably priced tire
The Continental ExtremeContact DW is $788 for 4 tires on TireRack.com
Here's a review on TireRack.com
I can't seem to find the ADVAN Sport tire in the 245/35ZR21 size though.
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Time to do some math here.
I base my calculations on Tesla's stated ranges and a simplified model for energy lost to drag (40% at 55mph) and energy dependency on square of speed for the drag, all other resistances independent of speed. Further I simplify that energy extracted from the pack is independent of power.
I arrive at the following table for relative range. I took it to 110mph because that is the top speed of the 40kWh model.
It becomes obvious that there is a severe penalty for going faster. Alas, many people pointed out that you cannot slow down in highway traffic without becoming a nuisance or even a safety problem.
Now let's see the figures for a brand new pack driven in range mode:
Note that these figures are based on a scenario, you drive (without AC/heating) until the wheels stop to turn and you need a plug immediately.
A more real-world scenario would be driving in standard mode where you use 80% of the pack capacity and have some 10% spare to reach your target:
If your pack capacity is derated to 70%, traveling in standard mode will take you
*) My conclusion: If you want to make road trips with the 40kWh model at highway speeds and the pack is operating inside warranted parameters, and you replenish 80% of pack capacity (the fastest way to charge) at any stop, you need charge points spaced every 75 miles apart.
I base my calculations on Tesla's stated ranges and a simplified model for energy lost to drag (40% at 55mph) and energy dependency on square of speed for the drag, all other resistances independent of speed. Further I simplify that energy extracted from the pack is independent of power.
I arrive at the following table for relative range. I took it to 110mph because that is the top speed of the 40kWh model.
Code:
mph 55 65 75 85 90 100 110
drag increase 0% 40% 86% 139% 168% 231% 300%
range 100% 86% 74% 64% 60% 52% 45%Now let's see the figures for a brand new pack driven in range mode:
Code:
nominal pack size miles
kWh
40 160 138 119 103 96 83 73
60 230 199 171 148 138 120 105
85 300 259 223 193 180 156 136A more real-world scenario would be driving in standard mode where you use 80% of the pack capacity and have some 10% spare to reach your target:
Code:
nominal pack size miles
kWh
40 128 110 95 82 77 67 58
60 184 159 137 118 110 96 84
85 240 207 179 154 144 125 109If your pack capacity is derated to 70%, traveling in standard mode will take you
Code:
nominal pack size miles
kWh
40 90 77* 67 58 54 47 41
60 129 111 96 83 77 67 59
85 168 145 125 108 101 87 76*) My conclusion: If you want to make road trips with the 40kWh model at highway speeds and the pack is operating inside warranted parameters, and you replenish 80% of pack capacity (the fastest way to charge) at any stop, you need charge points spaced every 75 miles apart.
I'm a bit curious about the revamped 0-60 times. Tesla was stating 5.6 long before they said the 300 battery would even be available at release. Originally the 300 wasn't going to be initially available. If the 0-60 times are a technical limitation, that means Tesla could not have hit their 0-60 mark at initial release with the 230 even though that was the implication for quite some time (well, the implication was 5.6s with any battery). The other option is they are purposefully limiting acceleration in smaller batteries to push people towards upgrades. Except for the 85kWh battery, the 0-60 times for the 40kWh and 60kWh aren't particularly good really, not for the competitors in the space. It's average at best and I wonder how much that'll hurt them, especially the 40kWh buyers.
goyogi
Member
I suspect it's to preserve battery life so that they aren't discharged too quickly. 6.5 second sprint isn't that bad especially with the torque curve of an electric motor the power will be instant.
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