This article provides tips on how to manage trips beyond the single-charge range of the car, aiming for minimum stress and maximum convenience.
The task
For day-to-day driving – say up to 180 miles/day (or 130 miles/day if you have the 60kWh Model S) – you can simply charge overnight and drive without worrying about energy usage. For longer trips, you will be using some combination of these techniques to extend your range:
- Charging. The obvious one – stopping to charge away from home. Almost any route will have more than one possibility to charge, so choosing the right one(s) and how long to stay at each is key.
- Pre-heat and range charge before departure. Ensuring that you can get the maximum range out of your first charge.
- Drive more slowly. Cruising speed has a huge effect on the total energy needed for a journey. There is a trade-off between driving time and charging time.
- Saving on heating and cooling. Aside from driving, heating is by far the biggest user of energy in the car. In summer, air conditioning can also make a noticeable impact.
In an ideal world there would be high quality charging facilities everywhere and you could just set off without thinking, but as things are today it is wise to have some sort of plan whenever you drive an unfamiliar route. Many straightforward trips can be planned with a few moment’s thought, or by using the Supercharger planner in the car, with only the most complex trips needing detailed advance planning. You certainly don’t need to do everything suggested in this article; you will probably find that some of it comes naturally after you’ve made a couple of trips, while the rest is available for reference on those rare occasions when you need to shave every last minute off the journey.
Planning tools
Since version 6.1 of the car’s internal software, there is an extremely useful tool on the main touchscreen. If you select a destination using the navigation system, a box at the bottom of the route display will show the amount of charge that is predicted to be left when you reach your destination and, if you tap this box, it will tell you the situation if you attempt to make a round-trip. The figures are displayed in green if the destination is easily reachable, yellow if it is marginal and you may need to drive more slowly than usual, and red if it predicts that you can’t reach your destination. The reason this is so useful is that the prediction is far more accurate than simply looking at the distance to go and your typical consumption: The prediction uses the actual route you will take, accounts for elevation changes, and uses the same speeds on each section as it is using to calculate the arrival time. You can still bust the estimate by driving faster than the ‘typical’ speeds for that road, but it’s an estimate you can be sure of matching if you need to.
When a navigation destination is active, more detail is available by opening the ‘energy’ page on the touchscreen and selecting the ‘trip’ tab. This shows your journey as a graph of charge against distance (the peaks and troughs of any hills en route are clearly visible!). This is useful in two ways: While driving, your actual progress is shown as a separate line and a continuously updated final result, so you can see at a glance how you are doing compared to the prediction. The other use is while charging mid-journey: You can see at a glance whether you have enough to reach your next stop or, if not, how much more you need to add before setting off.
Unfortunately, while the range estimator tool is extremely useful, the other recently-introduced tool – “Route planner” – which purports to plan an optimal route via superchargers, is almost useless. It will commonly suggest entirely inappropriate routes, sometimes suggesting that you go miles out of your way to charge for “0 minutes”, or suggesting that you make a U-turn and go back to a supercharger you have just left. This feature is best turned off – via Controls->Settings->Apps->Navigation, “Trip planner (beta)”
For desk-top planning in advance of a trip, EVtripPlanner.com offers a similar terrain-aware range estimator and a planning tool, which is especially suited to multi-hop Supercharger trips. You will also need maps to find charging resources other than Superchargers – there are many different maps available, though they are typically tied to a particular network or affiliation so that you will often need to consult more than one for a complete picture. Two crowd-sourced maps – PlugShare.com and OpenChargeMap.org – are particularly useful as they offer driver-contributed reports that help in locating the chargepoints and reporting any reliability problems. It’s much safer to base your planning on a chargepoint which shows regular successful charges by other drivers, rather than one that appears on an official map but may have restricted access or might not even have been installed yet. You may consider having the Plugshare/OCM apps on your phone and contributing reports when charging away from home.
Don’t underestimate the difficulty of finding a chargepoint that you haven’t used before, particularly in the dark. For Superchargers, the navigation directions may declare that you have “reached your destination” before you can see the charger but the marker on the big screen map is always in exactly the right place, so zoom in the map and drive until you reach it. A few Superchargers give you information on the screen for gate access codes or similar details to access the facility: tap the Supercharger symbol on the map, or the ‘finish flag’ if navigating there. Finding other chargepoints can be more difficult, and it is worth consulting Plugshare/OCM for other drivers’ tips or perhaps looking at Google Earth before you set out.
Plugshare also allows contributors to offer their home charge points to other EV drivers on a mutual help basis. Teslowjuice.com offers a Tesla-specific means for owners to offer their chargepoints to other Tesla drivers for emergency use.
The golden rule – panic early!
A good plan helps a lot, but sometimes things don’t go according to plan or you didn’t have a chance to make one. Driving along with 2 miles left on the display and no chargepoints in sight, your options are extremely limited: if you run out, your day will be ruined and your passengers will mock you for buying an electric car so, at best, you will have an extremely stressful experience. But it doesn’t have to be like that, and the key is recognizing the situation early enough that you still have choices.
The simplest example is picking the speed to drive. Suppose you have a leg of your journey where the trip energy graph shows you should have just enough charge to let you cruise at normal speed, but it starts to rain heavily. The wrong thing to do here is to press on at full speed and worry about it when you get closer to your destination – if you reach 10 miles to go but only 5 miles of charge left, you are in big trouble. Instead, you should slow down a little bit as soon as you think there could be trouble (or indeed start out slowly if the plan already looks tight) and keep an eye on the trip energy graph. With luck, the predicted energy at your destination will start rising and you can increase speed again, so driving at 60 instead of 70 for ten minutes will have added less than 2 minutes to your journey time and given you peace of mind. If the predicted energy isn’t rising then you need to carry on at 60 (or possibly divert for a different charging stop), so your early precaution will have prevented a disaster.
Another aspect of this is deciding when to give up on your original plan and switch to ‘plan B’. When you still have half a charge left there may be dozens of charging options within range, even if many of them are not in the direction you would ideally want to travel in, but if you wait until the battery is nearly empty then the remaining options may be very poor or even non-existant.
Energy saving
Energy saving might be a part of your plan, and it’s always an option when plans go awry. Sometimes it may work the other way around – you plan for a charging stop, but your energy use works out better than planned and you can skip the stop.
Driving more slowly
Cruising speed makes a huge difference to energy consumption on a long trip due to the effect of wind resistance, the net effect being that the energy needed to cover a given distance increases rapidly with speed. Drive 50% faster (say 90mph instead of 60) and you will use about 70% more energy. Slower is always better, down to about 25mph, below which the extra savings in power sent to the motor are outweighed by the cost of the car’s other systems (which use a fixed amount of energy per hour). In cold weather, the cost of running the heaters makes this break-even speed a little higher – 30 to 35 mph, depending on the temperature and how warm you keep the cabin.
On any trip where you are needing to charge en-route, driving faster is going to require that you stop longer for charging, so you may save time overall if you drive slower. As an approximate rule of thumb, it doesn’t make sense to drive faster than the charging speed (expressed in miles per charging hour) of your next en-route charging stop. So if your next charge stop is a 20kW chargepoint (which charges at a rate of about 60 miles of range per hour), then there’s no point driving faster than 60mph. If you only have a single charger in the car, or the charge point is a 7kW one (22 miles/hour), then you will want to be driving as slowly as is feasible.
Aggressive acceleration / braking also wastes energy so obviously you should avoid it, but this tends to be less of a consideration on the sort of road you will be using for long trips.
Pre-heat and range charge
Unless the first leg of your journey is to a Supercharger within easy reach, you will want to make sure you leave home with as much energy on board as possible – minimising the amount you need to charge later on.
If you are following Tesla’s guidance on preserving the life of your battery your normal overnight charging will be to only 80% or 90% full, so you will want to top up to 100% before a trip. If possible, you want to do this immediately before departure, for two reasons:
- The wear on the battery from charging to 100% depends on how long you leave the battery at 100% – driving off immediately after charging minimises the battery wear.
- In cool conditions (anything below +10C, but especially so below freezing), battery performance is constrained until the battery warms up. In moderate cold, this means that regenerative braking is limited – wasting energy when you have to use the conventional brakes. In colder conditions it is even worse – the car will burn battery power to actively heat the battery. Departing with the battery already warm avoids these losses and maximises the energy available for driving. The best way to warm the battery while parked is to charge it – the car will automatically run the battery heater if needed, and the process of charging inherently warms the battery further.
Another saving is to make sure the cabin is fully warmed before departure, using power from your home chargepoint rather than running down the battery.
If you have a garage, dual chargers in the car, and a high-power home chargepoint, then this is simple: Charge normally to 90% overnight then, as soon as you wake up in the morning, use the mobile app to set the charge limit to 100% and turn on the cabin heater. Within about 30 minutes the car will be ready to go with a warm cabin, warm battery and 100% charge, probably in about the same amount of time as it takes you and your passengers to get ready.
If you have less charging power available, or if the car is parked outside in extreme cold conditions, there is more of a problem: The heating and range charge will probably take too long to do it all just before you leave. If the car is very cold, it can take a significant amount of time to warm the battery enough for charging to start, even if you have unlimited power. If you have only a 7kW (30A) chargepoint, then the 10% charge takes about 1:15 on its own, and the cabin heater can take 7kW by itself, so charging and cabin heating have to be done one after the other. In these situations, the technique is to do the 100% charge overnight and to use the charge timer to make sure it finishes round about the time when you would be waking up (you will have to estimate the total charging time and work back to set the start time). You can then do the cabin warming manually. If you want to be really clever about it, you can make it a 98% charge overnight and just put in the last 2% manually as before.
If you don’t need to add extra charge, you can still heat the battery to some extent by switching on the cabin heating using the phone app: So long as range mode is not enabled (see below), this automatically switches on the battery heater too if the battery is below freezing. This will not heat the battery as much as charging it – not enough to get rid of the regen limit altogether – but does warm it enough that the car doesn’t need to run the battery heater while driving.
Things are easier in Summer, although you should still do your range charge at the last minute if possible, and cool the cabin before unplugging (just as with heating). Since the aircon uses less power than the heater, there is less of a problem with limited charge power and it’s also less serious if you misjudge it.
Saving on HVAC etc.
Next to driving, the cabin heater is by far the biggest use of energy. The seat heaters are much more efficient in comparison, so the first saving is to turn on the seat heaters and turn down the cabin temperature by a couple of degrees. This will give you the same level of comfort for less energy cost, so you may want to do this as a matter of course.
The next option is to select ‘range mode’ (under ‘driving’ on the ‘controls’ screen). This causes the cabin heating (or cooling) to use less energy, by following the set temperature less aggressively rather than lowering the temperature per se. Note that you may need to use manual rather than ‘auto’ settings for the fan and air distribution to ensure that you still have sufficient demisting/defrosting to see where you are going. Beware that (at least as of software version 6.0) there is an undesirable side-effect of enabling range mode: It prevents automatic battery heating during cabin pre-heat. You should therefore keep range mode switched off except when you need it. On dual motor cars (P85D, S85D), range mode also has an effect on the drivetrain performance.
In more extreme circumstances, you may want to turn off the heating altogether (set temperature to ‘LO’ and ‘A/C off’ if you want to maintain some ventilation while spending nothing on heating or cooling) and just rely on the seat heaters.
In summer, there is the choice between running the A/C and opening the windows/roof. At very low speed opening the windows is better, but at higher speeds this has a bad effect on aerodynamics and it uses less energy overall to keep the windows shut and the A/C on.
Note that turning off the radio, dimming the screens, avoiding use of headlamps etc. make almost no difference at all to the energy usage and so these are not worth doing unless you are really desperate (and probably only as a placebo even then!).
Charge stop planning
Superchargers
Supercharging is the only option that permits true long distance trips where you ‘drive all day’ with multiple full charges of the car fitted into rest/meal stops: Anything else is going to necessitate a break in the journey or will limit the trip to moderate distances. For the ultra long-range trips, there’s essentially three parts: getting from home onto the Supercharger network, travelling along the network, and reaching from the last supercharger to your destination. Often, the first supercharger will be within a full charge from home; otherwise it’s the same as any non-supercharger trip (discussed below). Travelling along the Supercharger network requires different technique to the final segment or trips just using individual Superchargers.
When travelling between Superchargers, there is little point in putting in more charge than the amount needed to comfortably reach the next Supercharger: the car charges much more quickly when it is near to empty, so spending 10 minutes extra charging before departure will only save you 5 minutes or less at your next charging stop. Tesla have tried to space the Superchargers evenly along popular routes, but inevitably there are variations and you will need to take on more charge at some stops than others. You should therefore try to plan your main meal stops at the places where you need most charging, and just have a comfort/coffee stop at the places where you only need 20-25 minutes’ charging. Sometimes the Superchargers are close enough that you have the choice of stopping twice or making a longer leg to the further one without stopping. If the intermediate stop is ideally located, then it’s better to make the extra stop: total charging time will be reduced as you keep the car close to empty. However, you need to allow time for the detour off the main road to find the Supercharger: even the best locations probably add 5 minutes to the driving time, while in others it could be up to 20 minutes extra. Sometimes it will be worth charging close to full and/or driving more slowly so as to avoid the extra stop.
It is quite common for the best route through Superchargers to be asymmetric. If you have a Supercharger close to home (say 30-50 miles), that’s fairly useless when starting out on a trip – the car will still be too full to charge at a useful speed. On the return journey however it may be ideal for a 10-minute top up with the car nearly empty. Often, the major roads offer you two routes around some geographical feature (mountain, big city, lake etc.) and if both routes are served by Superchargers you may find it better to go out one way and come back the other.
For your last (or only) Supercharger stop, there are several scenarios to consider:
- If your next stop is your destination and there is good overnight charging there, you just need to put in enough charge to reach it. This can make for a very short stop if your destination is not much further.
- If you are needing to stop again at a slower chargepoint, then you should carry on charging until the charge rate drops to the rate you will get at that next stop. For a rough estimate you want to charge about 70% full if the next stop is a full-spec CHAdeMO; 80% for a weaker CHAdeMO or 20kW AC; and 99% for anything slower, always ensuring that you have enough to get there. If you are want to stop at precisely the ideal point, you can wait until the charging rate shown on the screen (or the phone app) matches the charging rate at your next stop, but if you do this remember to look at the kW display (or multiply V x A), do not use the misleading miles per hour figure. Charging close to full can make for a long stop (an hour or more), so if targeting over 80% you will want to arrange for this to be your main meal stop, and you will be driving more slowly on the next leg.
- If your next stop is your destination but you aren’t confident of being able to charge there, then it is a tricky judgement to make: you need to allow for the next leg of this journey, the overnight stop, and the onward leg to your next opportunity to charge. This is much more difficult to estimate and, as it probably involves charging close to full, any extra that you put in for safety margin takes disproportionately long. If your plan is to stop overnight and then come back to this same Supercharger on the way home, then the navigation system will give you a good estimate for the round trip – but you need to allow a good margin on top for the overnight stop (discussed below). If you have a reasonable ‘plan B’ to charge somewhere else if necessary, then it’s OK to cut it fine, but otherwise the best advice has to be to wait the extra 20 minutes no matter how impatient your passengers are to move on.
Other en-route charging
All other public charging facilities are significantly slower than Superchargers, and they can also be less reliable. In some cases, the reliability of the equipment itself or the network operator’s willingness to maintain it is an issue but also, when charging in unfamiliar locations, you may have trouble finding the chargepoint or your map may not have made clear some critical detail about opening hours, access cards needed or equipment compatibility. For all these reasons, a route using Superchargers is often preferable even if it involves a significant detour. However, sometimes non-Supercharger stops can work out better.
The very fastest of these other charging options – CHAdeMO (using the optional adapter) or 20kW-rated AC chargepoints such as the Tesla HPWC (if you have dual chargers fitted to your car) – are, like Superchargers, feasible to use on a ‘while you wait’ basis. These give about 60 miles of range per hour (CHAdeMO ranges from 60 to 120 miles/hour depending on the equipment installed). While you wouldn’t want to wait the several hours needed for a full charge, using them to pick up an extra 60-100 miles over a lunch stop is feasible. This is particularly useful for out-and-back day trips, which are seldom going to be more than about 300 miles (say 6 hours driving plus a few hours at your destination): At only 150 miles each way there’s less scope to route past a Supercharger, but you only need to pick up a small amount of charge en-route. Unlike Superchargers, the speed of charging doesn’t change very much with the car’s state of charge so there’s no advantage in waiting until the car is almost empty before charging. If you have several good chargepoints to choose from it’s always best to stop at the first one as, if it’s out of order or occupied, you’ve then got the option of carrying on to the next one. Also, there is a tendency for low-capacity EV drivers to need a charge in the afternoon/early evening: if you can get your charging done at mid-morning, you avoid the rush later on.
Anything slower than 20kW – which includes the common 7kW/30A public chargepoints – is only useful for en-route charging if you are prepared to make a significant break in your journey to do something else. Visiting a tourist attraction, attending a business meeting, shopping, etc. can occupy the several hours needed to get a worthwhile amount of charge at these slow chargepoints. Obviously the ideal is to find charging facilities at the place you want to go, or indeed choose your entertainment based on available charging, but it can be quite practical to park elsewhere and take public transport, a taxi, or walk a few blocks. Many cities have installed chargepoints in the parking for suburban rail systems (London tube stations and Toronto Go Rail stations are examples), or at other park-and-ride facilities: park there and take a ride into town.
Destination charging
Finding a means to charge at (or near) your destination is extremely useful – there are a huge number of places that can be reached easily as a one-way trip with just Supercharging, but if you have to carry enough charge to take you from the Supercharger to your destination and back again, that is much more limiting. Also, when you make a long trip you typically stop for a few days and will need some charge for driving around the local area. So it’s extremely valuable to find some kind of charging at, or within walking distance of, your destination.
An increasing number of hotels have EV chargepoints installed – Tesla has a destination charging programme that offers subsidised charging equipment to hotels (currently only in N. America, China, Japan), and various grant schemes or simply enlightened hotel management have led to installations elsewhere. Generally you can find these through the various chargepoint maps (Tesla’s ‘find us’ map,. Plugshare, OCM, Zap-map or whichever is best in your area) more readily than by asking the hotels themselves, since reception staff are sometimes unaware of what has been installed. If you can’t find a hotel with charging, or are constrained to a particular hotel, you will have to approach them and see what can be worked out. There’s little point just asking for EV charging – that invites the answer “we don’t have it”. Instead, the approach of “I have an electric car that I need to plug in, do you have any power sockets (US: outlets) outside that I would be able to reach?” is more likely to produce results. Perhaps their maintenance department has some; perhaps they have power hook-ups for caravans/RVs; do they ever have events with marquees erected on their lawns, if so how to they get power to them? Sometimes a well-worded email works best, giving them the chance to ask around before replying; sometimes you need to get them on the phone and be persistent. Usually something can be worked out, even if it is only access to a domestic socket.
For friends and relatives, an ordinary socket in their garage is often the best that can be hoped for, but even this slow charging may be a big help, especially if you are staying for a few days. Maybe they have something a bit better – installed for a caravan/RV, or to supply welding equipment or similar for their hobby. In N.America, outlets provided for clothes dryers can sometimes be found in garages. People you visit regularly may be willing to install something specially for you.
In cities where you are more likely to be forced to park on the street and so can’t access a domestic socket in the house, parking somewhere nearby with public charging may be possible. A slow chargepoint in the next town is fairly useless – you need to stay there several hours to even make up the charge you wasted driving there and back – but a CHAdeMO point may be worth a short trip to access.
Overnight stops without charging
Sometimes you just can’t find a means to charge where you stay overnight. This might be obvious in advance, or it can arise when your planned charging falls through – you forgot your charge cable, the hotel’s advertised chargepoint doesn’t actually exist etc. In these cases, your planning needs to allow enough range to reach another charging option and an extra allowance for the stop itself. There will be some energy used by the car while it is parked: you should make sure that you have Energy Saving set to ‘on’ (under Controls->Displays->Energy Saving), in which case it will only amount to a mile or two of range lost per night. The bigger concern is warming up the car in the morning, which can cost several miles of range even in moderate weather, and maybe as much as 30 miles in severe cold weather. Unlike starting from a place with charging, you should not attempt to pre-heat if you are short of charge, since all of the energy will be coming from the battery and less energy will be used if you set off with a cold car and allow it to heat while you drive, just using the minimum needed to defrost the windows.
Equipment to take
It you are traveling a familiar route, it’s reasonable to take only the equipment you know you will need. Elsewhere, you really want all the cables and adapters that you own. Even if you think you’ve made an arrangement in advance with hotel staff or friends that you are visiting, it’s very likely that they have mis-described the socket that they are suggesting you use, or have proposed something inconvenient and impractical when a quick scout around outside will turn up a different type of socket that’s much more suitable, if only you have the right adapter to plug in.
Acknowledgement
Tips in this article have been collated from the experience of many people who have taken the trouble to post their trip reports on the Tesla and TMC forums.
If you think we’ve left anything out, please let us know via the ‘contact us’ link below.