Last updated 09-Jul-2022
The available range in a Tesla is the forecast of how far the car can go before it runs out of electricity and is a frequently asked question by many owners who get confused or frustrated by it. It's rarely a consideration with a petrol car as the available miles can be easily and quickly replaced at a fuel station and while most accept the manufacturers miles per gallon figure is far from the truth it's examined to any level of scrutiny. However, when you are in an electric car the available range is more important to allow for planning if and when you need to stop to charge.
The distance any car can travel on a full "tank", whether Petrol, Diesel or Electric, will differ depending on how it is driven, where it is driven, what it is carrying and the weather. Consequently, an EV with a quoted range of say 300 miles does not mean that it will travel 300 miles on a full charge.
The range in a petrol car, when they show a figure which is increasingly common, it is based on recent driving style and the number if a fairly accurate prediction.
Tesla do things differently as rather than show a figure based on recent driving history, they show it based on the rated range which at best, in summer, can be nearly correct, and at worst, in winter, a large over estimate. However, once you understand what the numbers represent, and what it doesn't, you can then decide whether you want to show miles or km, or prefer not to know and show %.
Before we look at the figures displayed; it is of course impossible to know exactly how far a car will travel on a given amount of electricity. The best you can do is come up with an educated guess for the range in miles or km. There are a number of reasons for this:
While other electric car manufacturers try and take into account these factors and give a real-world estimate, sometimes called a GOM (guess o-meter), the figure Tesla display is worked out differently and is in effect a proxy for the available kwh in the battery.
Tesla take the EPA rating (the official energy consumption figures per mile from regulatory testing) and assume that a mile requires that much energy. The battery management system works out how many kwh of energy are available and converts that to miles or km using that official efficiency figure. So, is this meaningful? The way we like to think of it is to compare it to say a lift. A lift might say "max 8 people" whereas the technical limit is not the number of people, it is a maximum weight. We intuitively accept that 7 very large people may be the actual limit and 9 or 10 children would be fine, but by using a number of people it is using something that we can more readily comprehend. Saying a car has 63.2kwh of available energy is accurate but not useful, converting that to 193 miles is more useful even though its technically less accurate.
In different countries and at different times, the official tests have been different which has resulted in different figures for the same car. The common tests have been EPA, NEDC and WLTP and these have also varied from giving figures which are close to the real world or very inaccurate. The problem is not unique to EVs. Even petrol cars have this problem as miles per gallon vary in different countries because a US gallon is a different size to a UK gallon.
Depending on the age and model of the car one of the following will be used:
US cars and cars in the rest of the world since about 2019 have displayed the Rated range based on the EPA testing standards in the US. The figure will vary by model as the efficiency varies, the Performance MX on 22" wheels being the worst with a Model 3 on 18" Aero wheels being the best.
One source of confusion is on earlier cars, in some countries, they used the NEDC figures which were very optimistic in comparison to the EPA figures. These cars usually had the option to show "Typical" which is described below, but two identical cars could be showing differnet figures depending on which was selected. It is also difficult to compare a care with the NEDC rating to a car with the later WLTP rating to see which is better as a lower WLTP figure could still result in a better real world range.
A second source of confusion is that Tesla now use the EPA figure in all cars, however in some countries the published figures are based on the WLTP testing cycle which is slightly different. A common question is "why does my car not show the rated range when full" and this is often caused by the differences in testing figures used.
When the NEDC figures were being used for the Rated range, this was so inaccurate Tesla added a "Typical" range option. This is virtually identical to the Rated range in concept, except the figure is based on a figure Tesla felt was appropriate. "Typical" is fairly close to the official EPA figures and so this option was not available on cars with the EPA rated range.
To change between Typical and Rated, you select which you prefer in menu, although increasingly cars now only show the rated range.
This was used in some of the very early cars and was based on Ideal conditions, thought to be around 50mph. The idea was to exaggerate the availabel range for marketing purposes, and this was only done in the US market. As battery sizes have increased the need to know the maximum you could eek out of a car has become less important. It is totally unrealistic and no longer used in cars made today.
In summary, each of the methods above just use a different figure to translate the available kwh into miles or km at the fixed ratio. If we revisit the lift comparison, it is essentially assuming different sized person as the typical person to calculate how many people can get in the lift, ie in the US it may be 85kg as average, in Europe 80kg.
When considering these figures, just like when getting into a lift, you need to make some mental adjustments to the figures for the current conditions. If you were getting in a lift with some pretty big people, or at say an airport where people have suitcases, you'd mentally adjust the capacity to a smaller number, and similarly if you were about to drive at high speed in an EV you would know the range would fall. Familiarity with your car and how it reacts to different conditions will help you make more meaningful adjustments.
As said, the above figures are all based on a fixed approximation of how much energy is required to drive 1 mile. Tesla do have other energy screens that can provide different figures:
The only place you can see a range based on recent driving behaviour is to display the energy screen and look for the projected range figure. This uses the average energy consumption over the length of the recent distance selected and uses this and the BMS reported available kwh to work out a range. There is also an option to show this on instantaneous consumption but this is of little benefit. This figure can fall rapidly in winter in cold weather due to the early parts of any journey being quite high on consumption, something thing that typically improves on a journey.
Using the same energy screens, if a trip is entered into the navigation, then the car will calculate the consumption for the journey and track actual to estimated consumption and predict an arrival state of charge. It will also suggest charging or reducing speed if required. This is probably the most useful method if on a single long journey.
In addition to the range figures, the car can show the economy of the car, this is typically the economy on the last journey, spanning short stops and the economy since last charged. It's worth knowing what your car used for Typical consumption as a mental reference against which you can compare, for instance a Model S is around 300 wh/m unless it's a performance which is nearer 330 wh/m. You can then mentally gauge whether you're exceeding this considerably or not.
All car manufacturers publish range based on official testing approaches and as suggested above, they all end up with a slightly different figure. But all these range calculations are from FULL to EMPTY. In practice, two things come into play when thinking of the real-world working range.
Tesla advises that other than the LFP battery packs found on the SR+ models built in China, the car should not be charged over 90%. For everyday real-world range, we think it's worth accepting this point to not over stress the battery while it leaves a bit more for the odd day when you need it. The second aspect is planning to end the day on empty is also risky. Few people would ever run a car to absolute empty before filling with petrol, and the same is true for batteries. There are a couple of good reasons for this, firstly it gives a safety margin in the case of a last-minute diversion or sudden change in conditions, and secondly the battery does not like being run too low. We therefore think a 10% to 90% working range of the battery is a sensible rule.
We also know the performance of the car is worse in winter and range can fall by 20% in cold conditions, rain etc. If the car is used for multiple short journeys, then the performance can fall further, but as a rule of thumb we work on 80% of the rated range being realistic in winter.
Taking these two factors into account, the working everyday range of an EV should be calculated at 80% of 80% of the rated range. A car with a 300-mile rated range is therefore capable of doing about 190 miles in winter without any real concern over recharging during the day or pushing the limits of the battery. If you routinely plan to do more than that in a day, then you will need to plan on charging in winter.
Batteries do lose some capacity over time and Tesla now warrant new cars to retain 70% of their capacity at the end of 8 years or the miles limit (which varies by model). Those displaying % will simply not see any reduction in the available miles at a given state of charge. Those showing miles may see a reduction over time.
There a few simply checks before you become too worried about degradation:
One of the most hotly debated topics is whether you should show a range at all on the dash or just show a percentage. The basic arguments for each follow:
We display range, we let the battery icon give us an indication of the fraction of how full, but there is no right or wrong here and owners should try both to see which they prefer.
One of the common reasons is outside of the US, the quoted range in the literature is based on the WLTP testing cycle whereas the car shows the range based on the EPA testing cycle.
If you have any wheels other than the standard, including removing the covers, and you update the wheels in the car, the range will alter to a lower figure.
The BMS can drift slightly and is pessimistic in nature, it will therefore under report available capacity. We have a guide on how to help the BMS recalibrate.
In cold weather, the battery simply can't make available the full capacity, again resulting in an under reporting.
The battery can experience some degradation, and some loss is inevitable. There is usually a small amount lost fairly quickly in the carís life, and then it plateaus to a slow degradation over time.
One aspect of Tesla ownership that surprises some people is the car uses electricity even when not being driven. This is called Vampire drain. This can range from a few miles per day to quite significant amounts of energy that could deplete the battery within a week. We have created a guide to vampire drain and how to minimise but the key points are:
To reduce vampire the following steps are recommended
A combination of the above will minimise the vampire drain in the car and reduce the amount of battery loss over night or whenever you leave the car.
We have created a guide to driving a Tesla in winter.
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