Last updated 27-Nov-2021
In many respects driving an electric car in winter is like driving any other car. The same laws of physics apply to ice, grip, traction, steaming up, frozen doors, etc, however there are a number of differences that drivers should be aware of irrespective of the Tesla model when the cold weather arrives.
We set out the key points for Tesla owners of all models including:
Range is limited considerably in cold weather especially at the beginning of a journey. Unlike a petrol car, an electric car does not create a lot of waste heat that can be harvested to heat the battery and the cabin. Cars are also effectively metal boxes in a 60mph wind tunnel and require heaters to keep things warm even when they are up to temperature in winter.
Heating the cabin can decrease range significantly (10-30%) due to the use of the heater and heated seats. The more efficient the car, like an M3, the more noticeable the required heating effect can be. This impacts shorter journeys more than long ones as once a car is up to temperature, the amount of energy required to maintain it is reduced, although still worse than summer driving.
Similarly, the battery can require heating, if not through a physical heater through increased internal resistance of the battery which in effect creates waste heat in the battery to warm it up. If you see a blue snowflake icon beside the battery icon it's because it's very cold. It will clear once your battery reaches a minimum temperature.
There is no magic way to remove the need for energy to heat the car, but if plugged in to a charger, preconditioning the car before use (see below) will draw the required energy from the charge point rather than from the battery leaving more available for the journey.
Charging the car to finish charging just before departure does result in the battery being a little warmer than it would otherwise be, and every bit helps, but the car needs to be charging for some time to build up any heat. If you get the start time wrong, the downsides of an under charged battery outweigh the potential benefits of a small amount of warmth from the charging finishing just when needed. Tesla have introduced a feature to help but this cycles the charging in the night and appears to want to utilise cheap electricity tariffs more than having the car in an optimal state for when you set off. They could just introduce a manual battery heater option if they wanted to deliver the latter.
Winter driving is also just more efficient because of heavier air and increased drag from wet roads. These factors accumulate with those of low temperature to make the cars less efficient.
It is not uncommon for people to see range as low as 50% of the expected range in winter. The worst case scenario is when the car is used for lots of relatively short journeys where the car cools down again before the next journey. This is also true for charging, especially supercharging, where the cold can limit the maximum rate even after a long drive where the cabin feels nice and warm. The battery may still be relatively cold. There are a number of issues which can reduce charge rates and owners can be concerned that they may be experiencing such an issue, this may not be the case in cold weather. If concerned then we suggest keeping notes on max charge rate, soc at the time, whether you are sharing a supercharger location, and using some of the tips below to see if it could simply be the cold.
Allow approx 25% extra range on a long journey and 50% if making lots of short journeys
Lowering the cabin temperature by only a few degress can extend range
Heated seats are more efficient that a hot cabin
Tesla now include heat pumps in their cars (all Mopdel Y and Model 3 and Model S from 2021). The role of the heatpump is to scavenge heat from the battery to heat the cabin as this is more efficient that resisitive heaters. While this works in many circumstances there are a few potential downsides including the battery taking longer to warm up as any heat extracted by the heat pump effectively cools the battery. The performance of cars with heat pumps in the cold appears to be reduced because of the length of time to heat the battery up and as a result acceleration and regen have been seen to be limited for longer and charging cars, especially those with the LFP battery, is much slower with a cold battery.
A cold battery will be most easily recognised by a dotted line on the power meter below zero. The dotted part of the line indicating that area is not accessible. Tesla appear to have become more conservative on the amount of regen possible in the cold, and less regen appears possible to how cars were a few years ago. As the battery warns up, more regen will be possible. It's important to recognise that reduced regen also means reduced braking and more application of the brake pedal will be required to stop. This can feel unnatural and very different to normal and the first time it is experienced it can feel like the brakes have failed.
Reduced regen is a limit on how fast Tesla thing the battery can safely take. Charging is exactly the same. Most domestic/AC charge points work at under 11kw and except in extreme cold conditions, this is rarely limited. DC charging however can be limited in the cold and 30kw or less even on a supercharger is possible. As a result charging a cold battery on a super charger can be a frustrating experience.
To reduce this problem, supercharge at the end of a journey rather than the beginning if possible, although be mindful not to charge to 100% and then leave the car full unless it is a car with an LFP battery.
If planning to supercharge en-route, select the supercharger as the destination. If the SoC battery is sufficiently high, the car will precondition the battery to be at the ideal state upon arriving at the charger.
As has been suggested above, preconditioning raises the temperature before driving reducing the amount of energy required from the battery once travelling.
Preconditioning can be triggered a number of ways, either scheduled or the easiest way we believe is simply to use the app 30 mins before departing. Turn on the features you require including heated seats and windscreen.
Preconditioning does not however automatically warn the battery and there is no easy way to manually turn on the battery heater, the car will turn the heater on if it feels it is required. (Technically cars with ludicrous can turn on battery heating by selecting ludicrous+ in the car but this is not advisable and not what the feature was designed for.). You may see a battery with a snowflake appear on the app display if the car feels the battery heater is required.
If leaving the car in extreme cold, the folding door mirrors can freeze closed. Turn off auto folding to remove this problem. On cars without the heated wiper element (typically Model 3 and older MS and MX without the cold weather pack) the wipers can be left in Service mode which means the contact patch with the glass will defrost more quickly if heating is turned on remotely.
Battery capacity falls as the battery cools, a range of 20 miles when warm can fall to below 5 miles if the car cools down significantly, and the drop can occur in only an few hours. Cars also have vampire drain which uses energy from the battery even when the car is not being used and over a few days those remainign miles can also disappear. As a result it is unwise to leave a warm car with a low state of charge without starting to charge. The car will generally warn you and recommend charging in this situation but it is worth planning your journey and charging to ensure you don't end up leaving your car with a low state of charge where there is no option to charge.
Autopilot and traffic aware cruise control (TACC) aim to maintain the car at a steady speed. If the car is going up hill it will naturally slow down and the car will provide more power to the motors to maintain the speed. This is perfectly normal and as expected. Problems can however occur if the car is driven on ice or other slippery condition, including deep water, where traction with the road is lost which cause the car to slow down. If TACC is engaged, the car will increase power in the same way it would increase power if the car slowed due to a hill. The increase in power can cause the wheels to spin and traction is further lost creating a vicious circle resulting in the car spinning out. This is not an issue unique to Tesla but still one to be mindful of in winter.
Regen can also cause the wheels to lock up on ice. This is particularly bad with 2 wheel drive cars as regen only works on the rear axle and not even distributed across all wheels which is what you would experience with a braking system. In extremely icy conditions consider setting the regen to low if you car supports this. Tesla have removed it as an option from some cars which we think is a poor decision.
Tyre pressures are sensitive to temperature. The correct tyre pressures are set at what is often referred to as Cold, but is in effect at the ambient temperature before use. This is because in use, tyre temperatures and consequently pressures increase and depending on how the car is driver the tyre pressures will increase up by a varying amount.
Often seen as the ambient temperpatures fall is owners reporting various odd pressure readings and alarms. Invariably the root cause is always low pressure in the tyres. The confusion often occurs because tyre pressure alarms use a hysteresis curve where the pressure reading that triggers the alarm is lower than the pressure reading that will reset the alarm. As an example, if a tyre is meant to be 42psi, if the pressure falls below about 38psi the alarm will trigger, but the alarm will not clear until the pressure exceeds approx 40psi. As the pressures reduce as temepratures fall, one wheel may drop into the alarm zone, but in use all the pressures will increase and the owner may find a displayed range of pressures of around 39psi and not understand why only one wheel has alarmed and their immediate assumption is a faulty tyre pressure sensor on that wheel.
We have not tried to address winter tyres here. In many countries winter tyres are a routine part of car ownership and the need for them varys by location. Teslas are often all wheel drive and the traction control systems are very good, these typically help primarily with acceleration. Physics and the weight of a Tesla, especially the MS and MX, still plays a significant role in the ability (or inability) to stop and corner so don't be fooled into thinking that the ability to pull away also means it is easy to stop.
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