Sunday, November 29, 2020

Range and range anxiety

If we are to move to a greener form of transport, the number of petrol/diesel cars must be reduced, that seems to be clear. For now, that also seems to mean to move to electrified transport, where battery-powered electric cars will be an important component. But for those considering such a conversion, one concept always crops up : range. Do electric cars (EVs) have the range I need, and what happens when it runs out of juice - will it then just stop suddenly and leave me stranded on the highway?

The answer to the second question is no: the car will then have beeped at you and flashed more and more insistently red for many miles warning you to seek a charging station, and maybe even told you where the closest one is, so do not worry about that: you do not need to have “range anxiety” for suddenly being blindsighted. 

The first of the two questions is however both controversial and vey confusing for the new user: what kind of range should I look for in a car, and what does that actually mean; how far will the car in reality take me? So many figures are flashing around to make your head spin, and they never match up. So, we should take it from the basics to see how to read this information. 

Range
“Range”, then, is a figure for how many km / miles a car will drive from a full battery (“full tank”, 100 percent) before the battery is completely depleted (0%). That figure is result of two factors: the size (capacity) of the battery, measured in kiloWatt-hours (kwh), and the efficiency of the car, measured either (European style) in how many kwh is used per km, or (US style) how many miles a kwh will take you, i.e. like miles per gallon (mpg).

The first figure, battery capacity is fixed (batteries lose a bit of capacity over time, about 1-2 per cent a year, but we will ignore that here). However, the efficiency of the motor varies a lot, it could be from 12 kwh to more than 20 per 100 km, for the same car. It depends on a lot of factors: your driving style, whether you go uphill or downhill, your speed, how many passengers you carry and even the weather. Much of this is the same for petrol cars, incidentally, we just do not worry so much about precise range for them. 

The two most important factors are your speed and the outside temperature.  EVs, unlike petrol cars, are more efficient at low speed, i.e. city driving. You normally worry about range only when you are travelling longer distances, but here the “sweet spot” seems to be about 80-90 km/h (50-55 mph). I cannot give you a precise figure for how much capacity you lose by increased speed, but let us make a guestimate of about a half to one percent per km/h increase, so that by driving consistently at 110 km/h (~70 mph), you lose at least 20 per cent efficiency compared to 80 km/h. 

The other factor is specific to batteries: they lose capacity when it is cold. The optimum here is somewhere around 20 centigrade outside temperature, we can calculate perhaps one percent loss per centigrade below that, so that 0 degrees gives a 20 percent loss, and -20 a 40 percent loss. These two are cumulative, of course, so if you drive on a motorway at over 100 km/h in -20, your capacity will be rather less than half of the leisurely summer drive. Now, people in Florida or Costa del Sol may not have to worry about that combination, but in Canada or Sweden that is certainly an issue. 

The various figures
This great discrepancy is reflected in the figures you see quoted in ads for EVs. Evidently, the manufacturers want the range to be shown as high as possible, so some independent bodies have devised a range of tests with a combination of city and highway speeds, under various conditions, to establish a way to compare cars. Unfortunately, they do not agree. There are three different sets of such range figures, and when you compare two cars, you must be certain that you are comparing them by same standard. The three are:

NEDC. This, the “New European Driving Cycle” is neither new nor European, it is the oldest and by common consent totally unrealistic, you could only achieve that result in a laboratory. It is therefore mostly abandoned today in Europe, but you can still find it used in China and partly Japan. You can of course compare two cars according to their NEDC figure, but know that neither will ever give you the range listed.

WLTP. In Europe, therefore, a more realistic test was developed, the “World Harmonized Light-duty Vehicles Test Procedure”. It is what you most often find used in Europe, if an ad there just says “range” you should expect it to be the WLTP range. However, many in Europe and the US consider this also to be unrealistically generous (“you can never, never, ever reach the WLTP range in real-life conditions”). This is a bit surprising for us up in the north, because in a recent comparative test made by the Norwegian Auto Association, a long-range drive on normal Norwegian highways, 38 out of the 39 models tested exceeded the WLTP range, some by a lot, up to 80-90 km (15%) higher than the official range. That was under ideal summer conditions, but other tests locally confirm that WLTP is very achievable. I myself am not at all an experienced EV driver, but regularly hit my car’s listed range or above on long-distance journeys. 

EPA. Nevertheless, the Americans normally use the range figure established by the Environmental Protection Agency. This is markedly lower than the WLTP. To see the difference, the small BMW i3 (33kwh) car is given a 300 km range by NEDC, 245 km by WLTP and only 172 km (107 miles) on the EPA standard - just over half of the NEDC figure. 


There are complex reasons for these differences, but probably the main one is that Americans are assumed to drive more on high-speed motorways, so that speeds of 70 mph or so (110 km/h) are given more weight in the EPA than the WLTP cycle, but also that the latter will seem less realistic in those European countries where fast motorways are more frequent. We do have such in Norway as well, but only on some main arteries, and the general speed limit is 80 km/h. In Western Norway, where I live, even the “arteries” may be narrow, winding and go through rather than around villages, so an average of 75 km/h is often the best you can get. So, the WLTP fits us better. How realistic the range figure is for you, will therefore depend on where you live. 

But how far can you actually drive?
However, even if the “range” in your favourite measurement says 400 km, that does not mean that you can actually drive 400 km in one go. The range figure is how far the car will take you from 100 percent charge to 0 percent - but you certainly do not want to drive it down to 0 percent, because then it will stop, and you have a couple of tons of car to lug around. And as we said, it will anyway start warning you at somewhere around 5-10 percent, which you should heed. Most likely, you would want to start looking around for a charger at around 15-20 percent, unless you know precisely where you are going and how far away it is. So, the “real” range you will actually want to drive is more like 80 per cent, or 320 km in your 400 km car (under its ideal conditions). 

Furthermore, you may not always start out with 100 percent charge. If you start from home on a long journey, you will probably charge it fully before you go. But if your trip is so long that you need to fill it up on the road, in a charging station (think “gas station”), you hit on a second snag where batteries differ from a petrol tank: It is a law of physics that a rechargeable battery charges more quickly when it is half-full than when it begins to fill up. We won’t go into the physics of it, but to protect the battery, the car’s electronics will begin to slow down the charging speed when it reaches about 80 percent of full charge. Typically, if it takes 45 minutes to charge from 20 to 80 per cent, then it will take another 45 minutes or an hour to top it up the last 20 per cent to full. You do not notice that on an overnight “slow” charger, because you are sleeping anyway, but when you are on the road, on a fast charger, you will notice, and it is often therefore advisable to stop charging at around 80 per cent. 

Now, nothing stops you from spending the extra time to fill it up completely, for instance if you have a long leg ahead of you where there are few chargers on the road. But if you can, there are a couple of reasons to stop at 80 in addition to your own convenience: One is if there is a queue of cars behind you waiting to charge. That should not be case, but it does happen when many people travel and charging stations are fewer than they should be. You may get a few angry looks if you are sitting there waiting for the meter to glacially advance from 94 to 95 percent. The other is economic, while some charging stations bill by the kwh, others calculate by the minute or a combination of the two. If so, you pay more, sometimes considerably more, for that last top-up than the rest of your charging. 

So, for your daily commute and charging at home, this is not an issue, you charge when you want to, all EVs on sale to day can easily handle your everyday travel of e.g. up to 90 km (50-60 miles) without any sweat, and most of us drive considerably less every day. It is for the long legs, your vacations trips or similar (or if you are a commercial traveller) that you have to consider this, and your “leg” or “stage” of travel from charger to charger is most effective if you limit them to from 20 to 80 percent of the listed full charge, i.e. 60 percent: Your 400 km becomes 240 km between fast chargers, and then add the reduction above from highway speed and cold weather. 

Short range, middle range and long range electric cars
So, with all of these deductions in range, you should go for the car with the highest possible “maximum range”, right? Well, that is where the debate goes. It is indeed typical that new owners who cross over from petrol cars do focus on range, and want an EV with as long range as they can get. More experienced EV users shake their heads at that, and say that this is rookie behaviour, wanting an EV to be as much like their old petrol car as possible. What if, they say, you make like two such long vacation trips a year, and buying a long range car saves you perhaps three or four charging stops, a couple of hours of waiting, in a year, is it worth the $10-20,000 extra you pay over a car with a more moderate range? Look more at other stuff, they say: how practical it is, how much space it gives you, and in particular: how fast it charges. Because that also varies, some models limit fast charging to about 45 kwh/hour, while others - often with smaller batteries - can top 100 kwh/h, or even beyond that. If so, you may charge a bit more often, but you will spend half the time on each stop. 

An electric car battary

There are some reasons to go for a car with lower range, all related to the fact that a lower range means a smaller battery in the car:
- One is thus price. The battery is probably the most expensive part of the car, so the larger the battery, the higher the price. The figure of $10,000 (or €) difference between a 250 km and a 400 km model is probably realistic, and $20,000 may be even more often the case. 
- The other is weight, batteries add hundreds of kilos to the car, which also means the car with a large battery needs to be more sturdy. That may impact the efficiency, a case in point is the quite popular Audi e-Tron, which is a roomy and luxurious car with a huge 95 kwh battery, but with 2,5 tons net weight - about a ton more than comparable vehicles - it barely tops a fairly mediocre 300 km (with very fast charging, though).
- The third, and most important for many, is the environmental impact. While EVs are the ultimate green zero-emission transport, at least on green electricity, the fly in the ointment is the production of the car, which does cause quite a bit of CO2 emission, mostly due to the battery (the motor itself is much simpler than a petrol engine). So, if you double the size of the battery, you also increase considerably the emission cost of producing the car, with the added problem of ethical production that batteries still (but hopefully not for long) have. 

In fact, one Japanese manufacturer, Mazda, has used this argument to intentionally limit the range (and battery size) of its most recent model MX 30 to 200 km, because that is what people need, it reduces the environmental impact of battery production and makes the car less expensive. 

How much do I actually need?
But is this true? What is actually the optimal range you should go for when choosing your EV, weighing these considerations against each other? Clearly, there is no single answer to that, it depends on your situation, your needs, your driving habits, and where you live. But, given the factors indicated above, let us suggest some scenarios. I will use myself as an example, so adjust to what is your situation.

Daily transportation (commute): The distance I drive to work and back again is about 30 km (19 miles). That means that even the oldest, banged-up and battery reduced Nissan Leaf from 2011 will satisfy my needs easily (it was the first “family size” EV, and should today still give you at least 90 km (55 miles) on a charge). So we will ignore that, any model will do. 

“First leg” weekend range: I do not have a cabin in the mountain, but I do have some relatives I may visit, who live about 150 km (90 miles) away. It takes me a bit over two hours to drive there, on our West Norwegian “highways”. I would rather like to make that distance without having to spend half an hour charging up on the road. However, I start from home at full charge, and know that I can charge up at arrival, so I would be willing to stretch the lower buffer down to 10-15 percent, i.e. that the real range I would hope for is about 85-90 percent of full charge. 

“Stage coach” holiday range: If you go on a longer summer vacation, perhaps you are more relaxed, perhaps you have kids with you who need a break every couple of hours. So, again, a “stage” of about two hours between stops could be useful. On the other hand, your charging on the road will be fast chargers, so try to stick to the 20-80 per cent formula, i.e. 60 per cent of full charge for each stage. You may travel part of that on fast motorways, where two hours actually could carry you 220 km (140 miles), but let us calculate here that you are taking the scenic route at a leisurly 80 km/h. 

Professional travel: If you are a professional traveller, you are probably less relaxed. Lorry drivers are required by law (EU?) to rest for at least 45 minutes after 4.5 hours of driving. And of course they would drive on fast roads if they can. So, to imitate that, we would need a rather longer stage; 4.5 hours at 110 km/h means 500 km (310 miles). Can any EV come even close to that on a single charge?

As we saw, this depends on circumstance. But to create a model for our example, let us compare three cases: First, how far will a car get us from home (fully charged) to a familiar destination, driving either at fast highway speed, or colder weather, like a coastal north European winter, of around 0 degrees. We suggested that either of those will reduce range by about 20 per cent. Secondly, a "stage" between two fast chargers for a family on a summer holiday, crusising on highways and backways, at 80 km/h average. And thirdly, the intemperate professional driver who will do 110 km/h and have as few stopovers as possible. What kind of official, listed range would we have to look for to comply with these needs (and, again for simplicity, I will here use the WLTP figures only, as those are the ones used in Europe, the miles are my division by 1,6; the figures are for illustration only).  

Small range city cars
Skoda Citigo
As examples of city cars, fairly inexpensive (as EVs go), we may take a used, elderly Skoda Citigo, listed at 130 km (81) miles range (today, this model performs much better), and the very popular (but now retired) VW eGolf, which had a 231 km (144 miles) range. That corresponds to a real-world range for “first leg” of 88 km (55 miles) for the old Citigo and 157 km (98 miles) for the e-Golf, while a “vacation” stage would take you 78 km (49 miles) and 138 km (87 miles) respectively. With the Citigo on a holiday trip at lower speeds, you would have to stop and recharge about every hour, on a motorway it would only last 30 minutes. With a Golf, you might get one and three quarter hour on each stage, unless you drive only on fast motorways, that would cut it to just under an hour before recharging. 
    The motorway speed of course gets you faster to your destination than driving at 80 km/h, even if you add in the charge stops. The time you gain by driving at high speed, when available, is more than you lose by having to stop and recharge more frequently, so there is no argument for driving more slowly just to gain efficiency. I am talking here of the inconvenience of having to stop and recharge more frequently. On the other hand, as these cars have small batteries, they will often also use less time in recharging - although newer cars (with larger batteries) also may have improved charging speeds.  
    Anyway, I would imagine for the Golf, that would be doable once or twice a year, but it would struggle to get me to my weekend spot without a charge stop. It may, at least in summer, but the margin might be close. Taking the Citigo on a long vacation really means you have to adapt to the car’s needs. But people certainly do, and it is a very affordable car, you could get it as almost new at less than €20,000.

Medium size cars
More realistic as the single family car are newer models with a bit more range, so their figures are more interesting. By “medium” we may think of cars like the Peugeot e208 (and its sibling Open e-Corsa) at 340 km (213 miles) listed range, the Hyundai Ioniq at 311 km (194 miles), and smaller in range than these, the again quite affordable MG ZS at 263 km (164 miles). How do these fit into our calculation?
The smallest of them, the MG ZS has thus a range not much above the eGolf. It would on a “first stage” from home take me 179 km (112 miles), so it would take me to my weekend destination without recharging. On a vacation trip, I would have to charge every two hours, but on motorways, a stage would only last an hour (126 km or 78 miles), so it is probably not a car for the professional traveller, but certainly within the practical for a family that might want to stop every other hour anyway.
Peugeot e-208

The two others confirm the same impression. The Ionic’s “first leg” would be just about 211 km (132 miles), and in my “vacation trip” at 80 km/h it would take two hours and 20 minutes before you need to stop. The Peugeot e-208 just tops that, two and half hours vacation speeds,  but an hour and twenty minutes at top speed on a motorway between charge stops. Starting from home, even driving at high speed, you would however reach 231 km (145 miles) without having to take a break. If you wonder how much 231 km actually is, it would get you from London to a bit beyond Bristol, or from Paris to Lille. 
That means that to achieve my first request, to get at least 150 km from home before charging, I would be looking at a car with at least 250 km listed range. That would exclude many used cars, but most new cars today exceed 200 km range. If, however, you are in the situation of driving quite a lot at higher speeds than 100 km/h; or you live a cold climate where below-zero temperatures are common, you might want to look at cars with 300 km or beyond that, to be assured you can drive for at least two hours between charges. There are currently a lot of new models in this “mid range” that will provide that. As EVs go, these are in the lower middle of the price range (€30,000 +/-), with the MG ZS definitely the most economical, but the others (and the many not mentioned here) are also priced within reason. 

Long-range cars
The third request, however, the 500 km or four hours non-stop on a motorway for the professional driver is way beyond the means of those cars. Can any EV go that long? I guess many, maybe most who have read this far, have been jumping up and down shouting “Tesla”. And, without doubt, Teslas are very much ahead in the long-range market, and have been so since they appeared in 2012. They are however, at least in Europe, fairly expensive, and there have in the last few years appeared a number of cars at a lower price point that also top a 400 km official range, some exceeding 500 km in some tests (like the Hyundai Kona, which did 568 km in the mentioned NAF test). But what does that mean in our “real-world” figures?
Although I said “above 400”, let us include the Renault Zoe, very popular in Europe, because it may fall around $30,000 in price and with 390 km (244 miles) listed range, clearly tops the “bang for buck” for long-distance cars. In the US, we have the Chevrolet Bolt, which WLTP gives 423 km (264 miles) range, and the “Koreans”, the mentioned Kona as well as the Kia eSoul and eNiro - the Niro has 455 km (284 miles) - also sell well (about €35-40,000). At the top end, we can then include the Teslas Model 3 Long-Range (560 km/350 miles) and the Model S LongRange (610 km/381 miles, at €80,000 or more), but other American car makers like the Ford Mustang Mach e and the luxury car Lucid boast of similar very long range; they have however not yet reached Europe. 

Kia e-Niro
With a Zoe, you can drive for about an hour and a half at motorway speeds (187 km/117 miles), a fraction of the required time. For a Bolt, the figures would be not much higher (203 km/127 miles). Even the most popular Tesla, the model 3, would fall short; 269 km (168 miles), or two and a quarter hours in our calculation. A Tesla model S is as close as you get among currently available cars: At 610 km official, we calculate it to 366 km on the vacation stretch (four and a half hours at 80 km/h, two and a half hours at full motorway speed). If you, however, take the time to fully charge to 100 per cent on their Tesla SuperCharger, the next leg could be somewhere in excess of 400 km, which is as close as we get. (Again, remember that we are here talking about the time it takes you between charge stops, not how often you have to charge on a given distance, evidently higher speed will get you farther in those two hours.)
In the last few months of 2020, we have seen or seen advertised a number of new models that lie within this same area, in particular the new VW models, the ID.3 (in Europe) and ID.4 (in the US), as well as the Skoda Enyaq, and coming models from Nissan and others. Most of them are not here yet, but seem in 2021 to be offered in a number of battery sizes, which would mean that the lesser expensive trims would fall into the medium-size 300-and-something listed range, while the more expensive will top 400 km or even 500 km, if claims are to be believed. That may change the picture, but not really by much, as far as can be seen; there are already many models in these ranges, and these models seem to be priced at the mid-to-high end, as the long-range cars already are (some of the new ones are more spacious, however, and have other new features that would make them attractive). 


275 km non-stop, four and a half hour, 
41 kwH (out of the car's 64 kwH)
Now, again, these are all figures from a spreadsheet, real life experiences will differ - and I have certainly myself driven my Kona for four and a half hours in a stretch, but that was across a mountain where my speed was nowhere near motorway speeds. The purpose of the exercise was not to recommend or disapprove of any particular model, but to indicate how to look at the “range” figures you see in the advertisements. They do certainly tell you something about each car relative to others, but you must not expect to actually be able to drive as many km or miles as the ad claims, without having a pick-up truck ready to tow the car in when you reach an empty battery. Calculate the actual figure to be perhaps two thirds or three quarters of the listed range, at best - or down to half the listed range if you live in a cold country. In addition, our notes here can perhaps provide some more indications. 

And do remember that 250 km or 150 miles is a considerable distance, and that a stop you take to charge the car will probably be the half hour or so you use to take a coffee or lunch break anyway. Whether you really need to - or want to pay premium in order to - travel more than that between bathroom breaks is really a choice only you can make.

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