Seeking more practical Model S range estimates

Seeking more practical Model S range estimates

Now that Tesla has at least 3 months of Model S beta experience (with the Oct 1 event onward), can Tesla provide a more reasonable estimate for range at real highway speeds?

85kWh battery:
Speed Range at delivery Range at 3 years
@55 mph 300 miles ?
@65 mph xxx miles ?
@75 mph xxx miles ?

I'm asking from a practical perspective (Yes, it's range anxiety in disguise!):
I have a recurring need to make a 210-mile round trip in a single evening, with no time permitted for a recharge. I need to know if this will fit my largest need (for gasoline).

Apologies if this is a repeat thread. searching the forums is, well, not impossible, but not easy.

AndyM, P1988

Jason S | 15. Februar 2012

We must guess for the Model S, since the effiency isn't known yet. There exists a graph for the Roadster and its drag but results vary depending on wheels, etc.

210 miles with zero recharge, overall, should be possible at reasonable speeds (65 - 70). However it might be difficult in extreme hot or cold weather (likely hot is a problem because cold would mean lower MPH and range goes up with less MPH).

Just guesses however. Might want to be safe and do a quick 10m charge at the local Walgreens somewhere on the drive.

Timo | 15. Februar 2012

My calculated guesstimate in another thread somewhere told that you lose about 20-25% from 300 mile at 75mph. 240-250 miles, something like that. It's not linear, you lose less with 65mph than average of 300 and 250.

AndyM | 15. Februar 2012

Excellent links and answers, gents. Many thanks!
My climate ranges between 45-85 degrees F normally, has flat roads, and a speed limit of 65. Unfortunately, no J1773 chargers mid-route. :)

Sudre_ | 15. Februar 2012

Tesla has stated that you get 300 miles at 55mph. If you are really concerned about the distance on the 85kWh battery just go 55mph in the slow lane :-) and you should have no problems.

You could go 75mph and save about 30 minutes on your drive. That would give you the extra time to charge for 30 minutes at a fast charger.

Either way you make the distance. Either way it's about a 4 hours drive. If you need to make it in 3 hours it might be a little tight after 3 years on a hot day.

Personally I would not think the battery degradation would be that bad after three years unless you are driving the battery hard and Tesla may not going to have numbers for that anyway.

AndyM | 15. Februar 2012


Driving a performance sedan at 55 mph on a US Interstate highway is just plain *wrong*. :) It is dangerous to drive nearly 20 mph slower than other traffic. And tragic to drive a Model S like a VW bus.

I think quoting this range is just as disingenuous as reducing the list prices by $7500 for the US tax break... you still have to front the cash. It's misleading.

jbherman | 15. Februar 2012

I agree that posting the price as $7500 less than the actual cost is misleading. That has bothered me since Dec. 21st. I understand the rationale, but I personally think it comes across a little seedy! They can't guarantee that the rebate will still be in place when some of the reservation holders take delivery. Plus, I don't think you get the rebate at the time of purchase, rather it's likely when you file your 2012 or 2013 tax return (depending on when you take delivery). Any accountants out there know otherwise? That means 9 months fronting the $7500 for early sig holders. Not a deal breaker...but doesn't inspire a lot of good feelings.

AndyM | 15. Februar 2012

jberhman, your understanding is correct. You have to file for it using IRS Form 8834, with your taxes for the tax year in which you purchase the vehicle. Chevy and Nissan advertise their EV's prices the same way.

David M. | 15. Februar 2012

If you want to receive the $7,500 credit before you file your taxes, you could adjust your withholding (W-2) or your Quarterly estimated taxes (1099) and receive the $7,500 throughout the year. However, if you do this, you must be convinced the rebate WILL still be in place throughout the tax year you take delivery.

Discoducky | 15. Februar 2012
cablechewer | 15. Februar 2012

I remember reading that the Roadsters have been losing less charge than expected per year. I think it was around 3%, however that is different battery tech and an older version of the PEM.

In talking with Tesla reps I have been told that cold weather is much kinder to the battery than very hot weather in the Roadster. In cold weather the battery heats itself somewhat just by being used to drive the car, but in hot weather they have to get that waste heat out and cool the battery. I don't know how having the battery in the floor tray of the Model S will affect the two temperature extremes (I would assume better heat dissipation in hot weather, but will we need it heated more in cold?)

So to partially answer the original question...
Assuming battery degradation is 3% per year range will drop by 9-10 miles per years. Everything else will depend on getting a graph like the ones displayed here:

olanmills | 15. Februar 2012

I honestly would not use the Model S in your scenario, if what you're saying is absolutely true, that you can't stop for recharges. Because you're pushing the limits of the range, and you don't know what could go wrong on your trip. Like maybe you would have to take a large detour or something. The weather and traffic conditions could unexpectedly change. My ICE car should be able to 325 miles or more with a full tank of gas, but for instance, if I was told that I needed to make a trip like the one you're describing, and there were no gas stations anywhere near my route, then I wouldn't do it.

Robert.Boston | 16. Februar 2012

@olanmills: "the traffic conditions could suddenly change"

The odd thing about EVs is that slowed traffic will typically increase your range. The sort of "rubber-banding" that characterizes heavy freeway traffic means that your average rate of speed is down a lot, reducing aerodynamic energy losses; and instead of braking, you'll be able to slow primarily with regen.

Timo | 16. Februar 2012

OTOH rolling resistance of the Model S is higher than Roadster and it is pretty constant thru the entire speed range so it causes the maximum range speed point to be higher than it is with Roadster. I'm guessing somewhere between 35-45 mph, so if the traffic crawls really slow for some reason you start to lose range again. Of course it needs to slow down a lot before it goes to less than 300 mile though.

mwu | 16. Februar 2012


"Unfortunately, no J1773 chargers mid-route. :)"

Do you mean J1772 instead of J1773? If so, have you done any research of your own on this? I downloaded both Recargo and PlugShare on my iPhone and I know of some J1772 stations that do not show up on those apps. I have been planning on getting out to those locations so I can enter the details into those apps, but I haven't gotten around to it. Those apps are crowd sourced, so stations can exist without them being listed.

"I have a recurring need to make a 210-mile round trip in a single evening, with no time permitted for a recharge."

Do you mean not enough time for a full recharge or not enough time to stop to get enough charge to make the rest of the trip? I am expecting that on trips I have almost enough range, but not quite I may stop just long enough to get the charge I need to complete the trip (hopefully without dropping my battery's charge too low). I would pre-plan the trip to ensure that charging times won't inhibit my schedule and that I won't drop the charge too low.

EdG | 17. Februar 2012

Sounds like a need for a good app: punch in how far you've got to go till your next recharge and the computer, using your own historical data (your tires, your driving habits' results), figures out how many spare miles you would have on arrival if you were to travel at various average speeds. It could display certain alternatives in red if those speeds were to result in less than 10 miles of spare range.

Included would be the computed travel time to destination. If you're considering a possible stop at a charging station, you might see that traveling at 55 mph would get you to your destination faster than going 70 because you could avoid a charge-stop.

Brian H | 17. Februar 2012

Sounds like a brainy no-brainer! ;p

I wonder how soon there will start to be a problem with contention for slots at the charge points. It could be a looonng wait if you're 3rd in line ...

ddruz | 17. Februar 2012

I have read that the Roadster has both a 100% full charge option and an 80% standard charge option (which charges to 90% and does not use the bottom 10%).

If you do a standard charge on the Roadster to 90% but find you need that bottom 10% while en route can you tap it and effectively use all of the 90% charge or is the bottom 10% hard wired into the standard charge option at the time of charging thus restricting you to 80% of battery capacity when you standard charge regardless?

Is it reasonable to assume the Model S will follow the same charging protocol as the Roadster? If so it gives us some additional guidelines in choosing battery size for the Model S given our estimated driving distances and charging habits. Most folks will probably usually standard charge to prolong battery life. It would be good to know whether that restricts us to 80% battery capacity or whether we really have 90% if we need it for emergencies.

The battery will also slowly lose capacity over time so we should plan to buy the battery size that will still hold the charge we need at the end of our anticipated lifetime ownership of the car, not the beginning. The Roadster seems to be holding battery capacity much better than estimated, losing less than 2% per year so far in a small study: I'm wondering if assuming 3% loss per year on the Model S is therefore reasonable.

Thanks to you knowledgeable forum members for considering my questions about standard vs full charging and reasonable battery degradation estimates.

SteveU | 18. Februar 2012

@ddruz: You can change the mode while driving so you can use the last 10%. (This was a firmware change. Originally you had to stop to switch modes. Even then you could get to the last 10%.)

I've got no idea how much extra degradation of the battery is caused by using some or all of the last 10%. I've never done that with my Roadster (and only used the top 10% about half a dozen times in three years).

ncn | 18. Februar 2012

210 miles? You'll be fine with the large battery. Even at 75 mph. Charge up in range mode. As the battery degrades, it might get harder to do without slowing down, but then we hope that there will be more charging points by the time that becomes an issue, right?

ddruz | 18. Februar 2012

@SteveU: Thanks very much. Excellent information. You've been using standard charge most all the time for 3 years now in your Roadster. How much maximum range capacity does your car have at this point compared to when it was new? Thx.