On range anxiety

It’s always fun when people approach me to ask a few questions or make a comment about the car. Two of the most commonly asked questions are:

  1. What is the range on the single charge?
  2. How long does it take to charge the battery?

This usually ensures that it is not going to be a short conversation ;). Both of these questions are often referred to as “range anxiety” when driving or owning an EV (electric vehicle). I thought it would be good to answer these questions here and hopefully relieve folks of some of that tension.

The maximum range on my Model S is about 240 miles (75 kWh battery). There’s a number of factors that will affect the real driving range though. Driving speed and style, weather conditions (temperature, precipitation, wind) and topology of the terrain – they all play an important part. On a warm and sunny day (85 F / 29 C) with no headwind, a person cruising at around 65 mph on a relatively flat terrain while avoiding abrupt acceleration or deceleration will probably get very close to the rated mile. Possibly even better. Any deviation from these conditions will most likely have a negative impact on the range.
While Tesla does a great job maintaining an optimal temperature of the battery pack, low temperatures will quickly eat up a good portion of the range. I am yet to experience the winter conditions, but those who own a car for some time suggest numbers in the range of 20-30%. I find it a bit extreme, so I will reserve my judgment till I go through at least one winter season. Other weather related conditions such as wind or rain will have an impact, too.
Same goes with driving style: the more heavy-footed you are, the more impact you will notice on how many miles are remaining before you have to make a “pit stop” to charge (similarly to a gasoline fueled car where you would waste more fuel when driving more aggressively).
One thing that differentiates EV from ICE (internal combustion engine) car is regenerative braking. Most, if not all, EVs are equipped with this functionality and it really helps to extend the range. It takes a bit of practice to get used to at first, but quickly becomes a second nature. I always use it to my advantage and apply the mechanical brakes only as a final assist to bring the car to full stop or in emergencies. Where this feature shines the most is during long descents on a mountain roads. You hardly have to press the brake pedal (just ease on accelerator) and the car takes care of the rest. How efficient can it be? VERY. Here’s an example from our road trip where we traverse parts of the Blue Ridge Parkway between Tennessee and North Carolina:

IMG_2598

Notice the big dip (in green)? It helped us to extend the range so much that on a 136-mile-long stretch of the road we have effectively consumed only about 70 miles of the battery’s range. Of course, this is an extreme example. Regardless, regenerative braking works and you should always use it to your advantage.

By the way, in case you were wondering, Tesla does a great job signaling the drivers behind you when regeneration takes place. One of the cool features is that you can observe it on the dash in front of you, as it will display the status of all vehicle’s lights (brakes included) on a miniature model of the car.

The last thing I want to mention regarding the available range is the available capacity. You don’t want to run your battery completely dry (just as you would not want your ICE car to go empty). Even if the car will let you drive all the way till it reads 0 (some people have already tried), it is generally not recommended for the sake of battery health and longevity. Others already covered the tips on how to maintain the battery at its optimum, so I won’t go into that here.

So, how long does it take to charge the car?

It simply depends on what type of charge you apply. Tesla is famous for its network of rapid chargers (called Superchargers). In United States they are conveniently placed along the major routes and allow worry-free travel across the country. Tesla is continuously expanding its Supercharger network (both in the US and abroad) which should help to make the range anxiety go away.
Back to the question though, typically you can get about 150 miles of range back within 30 minutes. The car’s built-in computer does a great job estimating the time it will take to charge in order to reach the next supercharger (taking into consideration pre-existing charge level and consumption to reach the next point) and it will propose how much time one has to spent at any given location.
When we first started using superchargers we would often stay longer (much longer) than needed, just in case. This proves to be a moot point, as the car’s brains will automatically start limiting the charging current in order to maintain battery’s efficiency, so you might spend another 30 minutes or more to gain the remaining 20% of the capacity. Eventually, we have learned to trust the computer more and be on our way rather than wasting time :).

The Superchargers work great on the road trips or any long distance commute. On a daily basis though, there’s plenty of other ways to get the car charged up. My typical daily commute ranges from 50 to 60 miles. I simply plug the car in the garage and go about the rest of my day. There are also plenty of public Level 1 and 2 charging stations available that can accommodate ANY electric vehicle, not just Tesla. Some of the most commonly found solutions would be:

  • NEMA 14-50 outlet (240V 50A) – it would restore about 24 miles per hour of charge in my car;
  • NEMA 14-30 outlet (240V 30A) – which provides about 17 miles per hour of charge, respectively.

In a worst case scenario I could easily plug my car to a common 110V 15A outlet to restore at least some of the range (it would be painstakingly slow @ about 3 miles of range per hour restored, but it would work!).

It is also worth mentioning that there is a number of useful mobile applications that help to find nearest charging outlet in case you end up in unfamiliar territory. Some of them are tied to commercial operators providing the charging infrastructure, some are maintained by community. Either way it is easy to find an outlet nowadays using any app.

The simple (and somewhat smart aleck-ish, I get it) answer to this question would be that… it doesn’t. Just plug your car at home when you’re done for the day and forget about it. It beats the 5 minutes of wait time at a gas station when refueling an ICE car, every time :P.

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