Tesla Model S Range and Charging: Some Clarifications
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.”
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