Tesla Model S Range and Charging: Some Clarifications

By · June 03, 2013

Tesla Model S

Yes, you can drive a long way, but 300 miles requires some adjustments. (Tesla Motors photo)

How far does the Tesla Model S go on a charge, 300 miles, right? If you read Consumer Reports’ celebrated rave review, giving the car 99 out of a potential 100 points, you’d think it was 200 to 220 miles. But range is a slippery slope, and some clarification is helpful here.

Maybe they were talking about the 60-kilowatt-hour car, Tesla said in an email. No, that’s not it. Consumer Reports Eric Evarts told me, “All our testing was on the 85 kWh model. We averaged 200 miles—about 220 in temperate weather, no heat or A/C, and as little as 180 in the winter with the heat on. We did not use the Max Range charging mode, because we think most consumers won't want to assume the risk to their batteries, at least most of the time, and think they want to know the typical, not max range.”

Stretched to the Max

As we all know, the Model S claims 300 miles on a charge, but Max Range charging is a big part of that, because it allows the battery 15 percent more capacity, extending the range. But that shouldn’t be something owners do routinely. As CR points out, “In general, we heed Tesla’s advice against charging for ‘max range’ due to the adverse effect on battery life, as any other owner would, and charge in ‘standard’ mode.”

Tesla's Shanna Hendriks says that owners really shouldn't worry about all of this. "Warranty is unaffected by charging to max range," she said. "In fact, as result of customer feedback, we have removed the Max Range versus Standard Range charge modes. Customers can now adjust the Model S charge level based on their individual and anticipated driving needs." On the newest cars, it's now a slider setting.

Similarly, range mode while driving also extends range, because it similarly allows the owner to tap into the bottom 15 percent of the charge. But the batteries really don’t like to be drained that far, so it’s something owners are probably going to use sparingly.

Everybody Does It

The Chevrolet Volt could have a longer EV range, but General Motors takes a conservative approach to how much of its battery power is accessed. In the 2013 Volt, the pack was slightly enlarged to 16.5 kilowatt-hours from 16, but the real deal was allowing the car to draw up to 10.8 kilowatt hours of that (up from 10.3 kWh in the two previous years). The result for owners is three more miles of EV range, from 35 to 38.

Many Model S owners wonder about often they should use range mode, but a Tesla Motors Club posting on “The Rules of Model S Tripping” throws caution to the winds. “Never, ever hesitate to use Range Mode. Ever,” it said. “Yes, there is a warning on the touchscreen about battery lifetime, but IMHO that warning is overstated. Tesla doesn’t want you leaving the car in Range mode for months at a time, because that will slightly increase the rate of degradation of the battery pack. We’re talking months here, not hours! A few hours at 100 percent charge has NO measurable impact on battery pack lifetime, and may actually improve battery pack balance.”

Beyond all of this, some Tesla owners say the rack up impressive range without thinking about it all that much. John Hennessey, a Connecticut 85-kilowatt-hour Model S owner, said he recently drove from Madison, Connecticut to Hingham, Massachusetts "with three other people, a bunch of stuff, a little heat when needed and a couple test drives, all on a single charge. The round trip was 278 miles and I returned with six miles left and 12 kWh (which meant that I had approximately 36 miles left)."

Hennessey drove 55 for most of that trip, because it extended his range. "If you need more range you can typically just slow down," he said.

Three Hours, and 141 Miles?

Speaking of Tesla range, how many miles do you get for 20 minutes on the company’s new 120-kilowatt Superchargers? In a conference call, CEO Elon Musk said such a charge will yield three hours of driving. “You can charge up to two-thirds in just over 20 minutes,” Musk said. “That means driving for three hours, stopping the normal amount of time on a road trip, grabbing food, and getting back on the road.” That claim is repeated here.

Ah, but Paul Mutolo, a fuel-cell chemist and director of external partnerships at Cornell University’s Energy Materials Center, says that, using Tesla’s own data, he comes up with a 20-minute charge range of only 141 miles. “You get 4.4 miles per kilowatt-hour added to the battery,” Mutolo said. In 20 minutes, you’re only going to get three hours of driving if you’re average speed is 47 mph.” In other words, don’t expect three hours of travel on the limited-access highways hosting the Superchargers.

There’s no doubt that you’d get a full charge in an hour from a Supercharger, but who wants to spend an hour at a rest area, even if it has a restaurant? This is about topping up and heading out. Tesla’s Hendriks tells me, “The whole idea of Supercharging is that it takes the same amount of time to Supercharge your battery as it does to stop for a quick bite to eat and a pit stop.”

Comments

· · 1 year ago

Hi Jim,

Great clarifying note! I figured out what Consumer Reports is doing; they are getting better but it's still clear that they are not used to how people use EVs. Around town on a day to day basis (at least with a long-range EV) it doesn't matter - I don't even look at the battery gauge, because I'm not going to drive that far. The extra range only matters on a road trip - which of course is when I DO charge in range mode. Consumer Reports could have made that a lot more clear; thanks for doing your part to help.

One mistake though; this sentence is not true:

“Similarly, range mode while driving also extends range, because it similarly allows the owner to tap into the bottom 15 percent of the charge”

The Roadster has a Range driving mode that worked kind of like that. But the Model S does not. There is a “range mode” for the climate control settings, but that’s it. The Model S always shows the whole battery; it doesn’t hide the bottom end like the Roadster did.

Similarly, this line

“Max Range charging is a big part of that, because it allows the battery 15 percent more capacity”

is not quite correct, as the difference is more like 10 percent (though the exact amount is hard to be sure of as Tesla doesn’t say; but from comparing miles available in each mode it looks to be right about 10%).

· · 1 year ago

By the way, while Tesla does say "300 miles", they are careful to say "at 55 mph" and then note that the EPA rates it at 265 miles. The product specialists in my local store say "265 miles". I don't even mention the 300-mile figure (though it is definitely possible!) and just give the 265-mile number when people ask as EPA numbers are the best for comparing different vehicles.

When somebody is serious about buying, I note that as mpg varies, range does too. A new owner should never stretch the range of their EV; get used to it first! I've never seen anybody buy a gas car and see how close to empty they can get the tank; I'm not sure why that is so popular with EVs. If you make regular charging stops, you can drive anywhere you like and never have range anxiety. Range anxiety will happen with gas cars too if you don't fill it up until it's empty.

I live in Seattle WA, and am driving to Palo Alto CA tomorrow. This will be my 7th long road trip in an EV. Though I can't wait for my 8th in January, when the Superchargers will be up and running along the West coast.

· · 1 year ago

I want to point out that when the new batteries of the long list companies that work on new batteries things will chage. Take Amprius; soon they will make the 700 Wh/L battery. This will make the Tesla Model S go for at least 800 miles. With 800 miles I would not even think of where to recharge it or how long it will take since I can not drive more that 5 hours after which I need to rest if not have a good sleep. While sleeping and only sleeping the car can be charged. With the 120 KW charger it will take 2 hours to charge. I will sleep longer than that. And that is to assume that I depleted the battery to zero! I think that we should push for these new batteries and not break the wings of Tesla.

· · 1 year ago

A Tesla sales person told me that Tesla rates battery degradation at 3% per year. That should be factored into the purchase decision, with the expected time the buyer plans on keeping the car.

Tesla has an excellent blog on efficiency and range of the Model S with graphs. The EPA 5 cycle test appears to correlate quite closely with driving a constant 65 mph.

http://www.teslamotors.com/blog/model-s-efficiency-and-range

Tesla says that air conditioning and heating will drop range by about 10-15 percent at 55 mph. Above that speed, it will have less effect, since the AC/Heating load is essentially fixed regardless of speed.

The 120 kW charge rate will decrease as your batteries reach a greater and greater state of charge. Maybe someone can confirm, but I don't believe that the 60 kWhr batteries will ever reach 120 kW even if fully depleted. I believe that rating is for the 85 kWhr batteries.

There is also an interesting thread on the Tesla forums regarding charging rates, and the number of cars charging at a single charging station. Apparently, whoever gets there first gets a higher charging rate. As the first car "fills up", and the charging rate for car #1 decreases, the charging rate will increase for car #2. If car #1 leaves, car #2 gets the full charging rate, the actual rate depending on how full the batteries are.

http://www.teslamotorsclub.com/showthread.php/15739-Barstow-Supercharger...

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