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The Secret Life of EV Batteries
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Previously published on CleanTechnica.com
You are probably familiar with the lithium batteries in your smart phone, tablet, or laptop. You are probably aware that they do not last very long. The number of charge, and discharge cycles is only about 600, before the battery is seriously depleted. So, if you are charging everyday, 365 days in a year, a battery won’t even last for two years. I have read comments by electric vehicle, detractors, gleefully declaring that anyone buying an electric vehicle, (EV), will find that their EV battery is defunct within a couple of years, because, typically, a lithium battery only lasts for 600 cycles.
Of course, you and I know that an EV battery will last at least eight years, possibly 10 years, or more, depending on how it is treated. I have had my electric vehicle for three years, and somebody owned it for a couple of years before that, and the battery is still going strong. So, obviously, the electric vehicle detractor is talking a lot of nonsense about their 600 cycles, and yet this seems to conflict with our own experience, of smart-phone batteries, and the like, which we know do not last very long.
The Puzzle
I did not like that puzzle, because it made me realise that I did not really know how this was possible. Could it be something in the battery chemistry, or the battery architecture, that was different for EV batteries. I am sure that many university research departments are working on battery chemistry, to try to achieve greater efficiency, and longevity in lithium batteries, or even a different kind of battery altogether. Readers of CleanTechnica.com will have seen many articles about such developments, but they are always at the early stages, promising, but a few little problems yet to be solved, not yet in commercial production, etc, and so could not explain much about the longevity of any existing EV battery. I had also read, that when Tesla chose cells for the battery pack in the original Tesla roadster, they chose a cell, the “18650” cell, that was already very commonly in use, and so, very cheap to buy, readily available, and reliable, but was used for portable electronics, and was not designed to be used in a traction battery at all. So, if Tesla was using common, ordinary batteries, with a common ordinary life cycle of 600 charge/discharge events, how could it be made to last such a long time in a Tesla battery pack?
A Visit to the “Library”
“Curiouser and curiouser”, said Alice, but there is no little bottle labelled “drink me”, to make her battery last five times as long. There is only one way to solve such problems, and less like Alice, by hitting the bottle, and more like Hermione Granger, by a visit to the library. Well, not the library as such, but the modern-day version, with a delve into the “restricted section” of the biggest library on Earth, the Internet.
More is Less
So, what was I able to find out? Firstly, all cycles are not the same. One way of increasing the number of charging cycles is by charging between less than full, and more than empty. The lowest number of cycles, and the shortest battery life, will come from repeated cycles of charging 100%, and discharging to close to nil%. Lithium batteries should never be entirely discharged as this drastically shortens their life. There are a number of possibilities, such as charging from 100% down to 50%, from 85% down to 25%, or from 50% down to 25%. It would appear that charging between 85% and 25% gives a good balance between battery life, and workable capacity
Charging Parameters
Cycles before capacity reduced to 85%
100% – 25%
2010
100% – 40%
2800
100% – 50%
2800
85% – 25%
4500
75% – 25%
7100
75% – 45%
10000
75% – 65%
12000
The Whole Truth?
When your instruments say your EV battery is charged 100%, is it really? When your instruments say your EV battery is down to zero%, it definitely is not. The battery management system will keep an emergency reserve for you, and after that is used up, will protect that last precious 5% or so, to prevent damage to your battery. Your electric vehicle will behave as if the battery were completely flat, when it is not, and might tell you it is down to zero, when you really have about 10 miles in reserve. I have experienced part of this for myself, when I miscalculated somewhat, and ended up on the journey home, with one flashing bar left on my battery indicator, which then disappeared to leave no bars at all. I then drove about 3 miles after that, running on fairy dust, with the car behaving completely normally, and arrived on my drive, under full battery power. So, obviously my instrumentation was telling a little white lie, just to scare me.
Black Box
For the avoidance of any confusion, I need to say here that when I talk about a “Battery Management System”, I refer to a wider concept than that. There are many systems in an EV which are separately identifiable, but that all gets too technical for most readers. Let’s use the concept of a “black-box”. We do not need to know all the intricacies of what is in the box, but we can be aware of the inputs, and the outputs. Think of a PC box, or your tablet: you know how to use it, without knowing all the intricacies of what goes on inside the box. So, when I say “Battery Management System”, I am including all the complex systems between the battery and the motor, the battery and the charging ports, and the driver information outputs on the dash board, or your touch screen. What I am saying is that there is not just a battery, and a length of wire going to the motor, and a pedal like on a sewing machine to control the speed: there is a much more complex system than that, but I am not going into all the technical details.
Your Virtual Battery
What if the battery management system charged only up to, say, 80%, and kept 30% in reserve, but displayed this as 100% to zero, with a range of, say, 100 miles, (160kM), then, as the battery lost capacity, the system charged it up to, say, 90%, and kept 20% in reserve? You would not be aware that your battery had lost any capacity at all, because your instruments would still be displaying the virtual battery as 100% to zero, with the same range as before. That is a secret way that electric vehicle manufacturers could make it appear that your EV battery has lost no capacity, when in actual fact, it has.
Reserved
Virtual Battery From 0% – 100%, Range 100m
Reserved
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
Reserved
Virtual Battery From 0% – 100%, Range 100m
Reserved
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
Reserved
Virtual Battery From 0% – 100%, Range 100m
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
That would lull an EV owner into a false sense of security, because they would think their battery has not deteriorated at all, in how ever many years they have been using it, but once it reaches the stage in table 3, the virtual battery has no room left to expand, and range will begin to drop off for real. An ageing EV battery will also be more susceptible to damage from fast charging, so deterioration could become quite rapid. I am not saying that any particular manufacturer does this, because I haven’t found any information from them, but I have read about this idea in general as if it were a common practice.
Controlled Voltage Level
For the avoidance of any confusion the voltage level is pretty much synonymous with the percentage of charge I have just mentioned so when we talk about “100%” charged we are talking about a battery fully charged up, which will then have a voltage in each cell of around 4.2V. A flat battery will have a voltage in each cell of 3V or less. So, in some ways this following chart is just a different way of expressing the same thing, but is more precise. Percentage of charge is not to be confused with percentage of capacity. The capacity of a new 40kWh battery is to provide 40kW for a whole hour. If the capacity reduces to 75% it will only be able to provide 40kW for 45 minutes, or 30kW for an hour.
Where a lithium battery cell has a nominal voltage of 4.2 V, it can be charged up to slightly more than 4.2 V, or slightly less than 4.2 V. The difference between charging to only 3.9 V and 4.2 V can be as much as four times the number of cycles, and longevity of the battery. That gain in longevity has to be balanced against the loss of some of the battery’s full capacity. This is one secret that manufacturers employ in their battery management systems. Because this reduces the effective capacity of the battery, the battery has to be much bigger, physically, to provide the same level of capacity. This is one reason why EV batteries are so big and heavy, with relatively low efficiency. They could provide the same capacity, with a smaller battery, where all the cells are charged to the full voltage, but it would not last so long.
Voltage
Cycles
Capacity
4.25
200–350
105–110%
4.20
300–500
100%
4.15
400–700
90–95%
4.10
600–1,000
85–90%
4.05
850–1,500
80–85%
4.00
1,200–2,000
70–75%
3.90
2,400–4,000
60–65%
3.80
See note
35–40%
3.70
See note
30% and less
Controlled Rate of Discharge
We also need to look at discharging. Where a lithium cell has a nominal capacity of say 1500 mAh, that capacity could be provided by giving 1500 mA for an hour, 750 mA for two hours or 375 mA for four hours. If we call 1500 mA in one hour, 1C, then 750 mA would be 0.5 C, and 375 mA, 0.2 5C. Where the batteries are never discharged at a rate of more than 0.2 5C, they will last much longer than if they are drained at their full capacity. This is a secret of EV battery packs, where the control system ensures discharge rates are never excessive. This is another reason for EV battery packs being so big and heavy, not just for the sake of range, but for the sake of minimising the rate of discharge, and so, further extending the battery life.
A Tale of Two Batteries
So, it is as if you have two batteries in your car: one is the physical battery, and the other is a virtual battery, as presented to you by your instrumentation, and as created by the battery management system. Your physical battery, were it all to be made available to you, would be much bigger and more powerful than it appears. The virtual battery, created for you to use by the battery management system, that you see through your dashboard displays, is smaller, less powerful, but longer lasting. All these secret techniques that go on stealthily in the background and, probably unknown to you, are what constitutes the secret life of your electric vehicle battery.
Don’t Leave Your Battery in a Locked Car
That subtitle normally relates to dogs, and is a cryptic clue to one further secret, which although nothing to do with charging and discharging or even running the electric vehicle at all, is something to be aware of. Where a lithium battery is charged to 100% and then left stored, unused, but at a temperature, above 25°C, then degradation will occur without using the battery at all. So, if you are living somewhere hot, where your garage reaches high temperatures, or even high temperatures exist on your drive, it is not such a good idea to leave your electric vehicle fully charged up for long periods, unused. It might even be worth having a dedicated solar panel on the garage roof to power air conditioning in your garage during the heat of the day, to keep your battery cool, when not in use.
°C
Capacity after 1 year stored at 40% charge
Capacity after 1 year stored at 100% charge
0
98%
94%
25
96%
80%
40
85%
65%
60
75%
60%
(after 3 months)
Limitations on Fast Charging
Despite people’s impatience about waiting to charge up, there are limits to safe, charging-currents, if you do not want to damage your battery. A power level of only 3kW can produce enough heat to warm up an entire room. A power of 50kW is a huge amount of power to put into any electrical system. Impatient or not, regardless of what people “want”, there are limits to the amount of power you can safely put into an EV battery. Ideally, the fastest charge rate for a 50kWh battery is 50kW over a period of 1 hour, because that exactly matches the characteristics of the battery. However, charging from 30% to 80%, where 80 less 30 is 50%, representing only half the battery, the rate could be 50kW over a period of half an hour. To bring charging time down to 15 mins, would require 100kW, which is double the ideal. The combination of false capacity percentages, and lower charge voltages, plus over-sizing of the battery, and carefully designed battery chemistry, all helps to make faster charging possible, but there are limits.
People should not expect charging times to come down much below 20 mins, or ever be equivalent to filling a tank with fuel. Fifty litres of fuel represents 600kWh of energy. A 600kWh battery would weigh 6 tons. That makes a 50kWh battery weigh half a ton, so do you really want to be carrying around more than half a ton, on all short journeys every day, just to save a few charging stops on the occasional long run. People are just going to have to learn to be more patient, if humanity is to survive much longer.
Further Information
One thing I have not included in this article is any specific reference to any specific manufacturer or car. I have e-mailed Nissan, and Tesla about their battery management systems, but have received no reply at the time of publishing.
I did find the following statement about batteries on the Tesla site –
factors affecting cycle life are tied to how the cell is used. In particular:
Avoiding very high and very low states of charge. Voltages over 4.15V/cell (about 95 percent state of charge [SOC]) and voltages below 3.00V/cell (about 2 percent SOC) cause more stress on the insides of the cell (both physical and electrical). Avoiding very high charge rates. Charging faster than about C/2 (two hour charge) can reduce the cell’s life.
Avoiding charging at temperatures below 0° C. (Our design heats the pack before charging at cold temperatures.)
Avoiding very high discharge rates. (Our pack has been designed such that even at maximum discharge rate, the current required from each cell is not excessive.)
There is a huge difference in cycle life between a 4.2V/cell charge (defined by the manufacturers as “fully charged”) and a 4.15V/cell charge. 4.15 volts represents a charge of about 95 percent. For this reduction of initial capacity (5 percent), the batteries last a whole lot longer. Unfortunately, further reduction of charge has a much smaller benefit on cycle life. Understanding this trade-off, Tesla Motors has decided to limit the maximum charge of its cells to 4.15 volts, taking an initial 5 percent range hit to maximize lifetime of the pack. We also limit discharge of our battery pack to 3.0V/cell and will shut down the car when the batteries reach this level.
The information about batteries was obtained from BatteryUniversity.com, which is a very useful site for technical information on batteries of all kinds.
Andy Miles
As a child, I had the unrealistic expectation that I would learn about, and understand, absolutely everything, during the course of growing up. Now, at the other end of life, I am fully aware of how much I have not learnt, and do not understand, and yet, remain interested in everything. My education, starting with an arts degree, and going on to postgraduate studies, in everything from computer science, to hypnotism, reflected my broad interests. For 20 years, I worked in local government, and am now retired, living in North Leicestershire in the UK, with plenty of time for doing whatever I like. I have always had a keen interest in everything alternative, which includes renewable energy and energy efficiency and, of course, electric vehicles. So, naturally, I have taken ownership of an EV, now that they are affordable and practical forms of transport. Writing is also one of my great pleasures, so writing about EVs and environmental issues, is a natural evolution for me. You can find my work on EV Obsession, and CleanTechnica, and you can also follow me on twitter.
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Road trips are the final frontier for EVs to totally outshine combustion engine vehicles. Already clearly a better technology than combustion vehicles in every other respect, of all the EVs currently on the market, only Tesla so far provides truly compelling road trip ready offerings. This is an area that other car makers need to pay much more attention to if they have a hope of ever competing with Tesla’s stratospheric demand and world leading EV sales volume.
The recently announced Tesla model 3 long range all wheel drive version will be a compelling combination of road-trip-readiness and affordability, with likely the longest range of any EV, impressive energy efficiency even at highway cruising speeds, and reliable fast recharging speeds. According to past experience of the dual motor range advantage of all wheel drive models, common sense suggests that the newcomer will provide a 4-5% range improvement over the single motor version, which is itself a very compelling road trip vehicle. Official EPA and WLTP vehicle range ratings are only useful for relative comparison (not nearly accurate in absolute terms). More reliable real world range calculations and data (such as those by long time contributor to the Model 3 Owner’s Club Forums TROY) indicate that cruising range of the dual motor version at 75 mph [120 kph] will be around 275 miles [443 km] in optimal conditions. At a more leisurely 70 mph [113 kph] this increases to 299 miles [481 km] of range. This thing will take road trips in its stride.
Tesla still wants to sell good numbers of its model S and model X, so has historically slightly downplayed the model 3’s official range, and will likely continue to do so for all model 3 variants for a while longer. This will remain the case until the S and X get a refresh to further differentiate their range and features from that of the less expensive model 3 offerings, perhaps later this year. For now, the model 3 is significantly more energy efficient than the bigger and heavier S (not to mention the X), with even the official EPA figures giving the 2018 model S 100D a highway energy consumption of 102 MPGe and the model 3 LR 123 MPGe. Although EPA and WLTP metrics are notoriously untethered from reality, they can be useful as a basis for comparing energy efficiency of different vehicles. The real world driving ranges of the longest range versions model S and model 3 are similar, though the model 3’s energy efficiency allows it to achieve this with a significantly smaller battery, which helps in reducing its relative cost, and the recharge time needed to regain a given range. We know that Tesla requested the EPA to give the model 3 Long Range (3 LR) an official range of 310 miles, when it in fact measured 334 miles on the standard test cycle. For the same reasons, Elon has suggested that the model 3 Long Range all wheel drive version (3 LR AWD) will have the same official range as the single motor model 3 LR (310 miles), even though sensible estimates suggest a 4-5% boost in range.
Either way, the good news is that for anyone who has wanted to get into a relatively affordable EV and has been concerned about still being able to do comfortable road trips, the newly announced model 3 LR AWD will have very impressive range capabilities and (along with several other existing Tesla models) will be no less convenient than a gasoline car for road trip purposes (and in fact a much better experience than a gasoline car all round). Whilst the single motor version is already very capable of making practical road trips, the dual motor version pushes the bar even higher. With the standard aero wheels, and in ideal conditions (more on what this means below), the model 3 LR AWD’s 100% range when continuously cruising at various speeds (where permitted) should be as follows:
A note on Ideal Conditions vs. the Real World
Folks coming from a combustion engine experience may not be accustomed to thinking about how real world environmental conditions can effect the energy use of the vehicle. But the diesel emissions scandal has clearly shown that combustion vehicles are in reality a lot less energy efficient and a lot more polluting than official ratings and manufacturers’ claims make them out to be. The challenges of real world conditions apply to all vehicles, whatever the power-train. ‘Ideal conditions’ means mild weather and mild ambient temperature on a decently paved road without the need for much HVAC and without significant headwinds, amongst other things. These ideal conditions don’t happen too often, so all vehicles use a bit more energy than ideal conditions suggest. When, for example, a 10 mph headwind is present you should expect closer to 80 mph equivalent range figures when travelling at 70 mph. Crosswinds at these mild levels are less of an energy concern and of course tailwinds will help your energy consumption, if you are lucky enough to get them.
HVAC can use significant energy in extreme temperatures. For gas vehicles with less efficient HVAC, the energy hit can be as large as 20%. EVs are usually designed with much more efficient HVAC systems, with a more typical 5-10% hit on your energy use, depending on circumstances. Another EV advantage is that you can remotely pre-heat or pre-cool the interior (and pre-condition the batteries) when the vehicle is still plugged in to a recharging point, without using any battery energy to do so. Mid trip, EVs can do the same whenever they are recharging. A combustion engine vehicle needs to have the driver present and the engine turned on before doing these things, potentially wasting both energy and time, to e.g. de-ice the windshield or remove oven-like cabin temperatures before the vehicle is drive-able.
Tesla guru Bjorn Nyland recently analysed energy consumption under HVAC use on the road and found that AC cooling the cabin of his model X from 77-80 Fahrenheit (25-27 Celsius) down to 68 Fahrenheit (20 Celsius) added around 5% to energy use compared to having it switched off (he conducted the test at different speeds with similar % results). In more extreme conditions, your EV’s HVAC could add 10% to energy use, with a corresponding range hit, although this will depend on your driving duration, speed and other factors. The good news is that EV HVAC systems are becoming more efficient all the time (e.g. using heat pumps rather than resistive heating).
Elevation changes tend to average out over long distances, so shouldn’t be an issue during most road trips. Rain and poor surfaces can have a modest energy hit also. Therefore in moderately poor conditions (modest headwinds, and high/low temperatures), you may use up to 20% extra energy on your journey compared to the above ‘ideal conditions’ figures (EV drivers please join in the comments section to add your own experience on this). As a general rule, if you slow down fractionally in tough conditions (sensible anyway in rain, wind or extreme cold) you will be able to compensate without much trouble. The range chart figures above demonstrate that a 5 mph [8 kph] speed trim at highway velocities will save you around 10% energy use, giving you 10% higher range and often resulting in an overall journey time not much different. The same is true in most vehicles.
EVs and Road Trip Readiness
As I noted in a previous piece, the freedom to hit the open road is something we have long taken for granted with our cars. Despite the fact that for most of us it is something we do just a handful of times a year, the possibility of being able to do so has a strong appeal. Most folks want to buy a car that is capable of doing road trips (especially if it is our only car, as it is for most car owning families worldwide), however seldom we actually make such trips.
Since total energy storage is a key factor influencing driving range (along with energy efficiency), this is an area where gas vehicles have historically had a residual energy advantage over EVs. However, Tesla’s large battery models, designed both to have world leading energy efficiency, and fast, reliable, and convenient recharging, have long since had sufficient range to enable practical road tripping. Road tripping in a quiet and vibration free EV is also a lot more pleasant and less tiring experience than in a combustion engine vehicle.
A road trip in an EV typically involves initially driving from fully 100% battery state of charge (SoC) down to no less than 10% SoC, and then recharging. 10% is the recommended minimum because you don’t want to count on finding the right charging spot when you are getting close to empty (just as you wouldn’t in a gas car), and also because it is not great for long term battery health to habitually drop much below 10% SoC. DC fast recharging back up to 80% SoC happens relatively rapidly in well designed EVs (including all Teslas, though disappointingly few others, as we will see below), but all vehicles typically slow down their rates considerably above 80% SoC, again to preserve battery health. So recharging much beyond 80% is a usually a inefficient use of your time if you are mid trip, though if you are ready for a longer break, charging to 90% SoC or more may be convenient. Here’s a useful illustration from European recharge specialist Fastned, based on recharging data from hundreds of Hyundai Ioniq fast charging sessions:
The Hyundai Ioniq DC fast charging capability (based on Fastned’s real world data)
So on a planned road trip, your first driving stage can make use of up to 90% of your battery’s rated range and subsequent stages will likely be using closer to 70%. In a model 3 LR AWD, assuming driving at 70-75 mph [113-121 kph] and experiencing moderately poor environmental conditions, you can still expect to cover at least 200-215 miles [322-346 km] over your initial stage (using 90% of battery charge) and then take a 30-40 minute break before covering at least another 155-168 miles [250-270 km] (using 70% of battery charge). That’s almost 3 hours of initial driving (if you’re up to it – 2.5 hours is the recommended maximum healthy driving duration before taking a break). Thereafter you can drive 2 to 2.5 hour stages at 70-75 mph [113-120 kph], repeating as often as you need, with short breaks in between.
With these capabilities you can make, for example, a trip from downtown LA to downtown San Francisco (380 miles) without any inconvenience, even in poor environmental conditions. It takes around five and a half hours of driving at highway speeds with a 35 minute break just past the mid point. That’s the typical driving duration and the comfortable choice for a break – whatever your vehicle – on such a long drive. With kids on board, older folks, a dog, you’ll likely want to stop more frequently. Last time I made the LA to SF road trip (with a friend, in his ICE car) we stopped for a 40 minute food break along the I-5 highway and then had to dedicate extra time for gasoline refuelling. An EV charge session doesn’t need to be attended (smartphone apps allow you to remotely monitor charging progress), so you can bundle the food break into the recharging period. Any average road trip would follow a similar pattern of driving time and break time, be it from Paris to Frankfurt, Milan to Zagreb, Shenzhen to Xiamen or what have you. If the trip was longer still, you’d want to stop for further breaks every two to three hours of driving anyway.
We are now at a point where Tesla’s EVs can take such road trips in their stride, with no practical difference in comfortable road-trip-ability compared to any other vehicle.
Where are other manufacturers on the road trip readiness front?
Still lagging Tesla by a long shot, unfortunately. We all wish they would step up, but they are not making nearly enough effort. So in this section let’s review their progress and give them some constructive criticism.
Nissan Leaf 40 kWh
New Nissan LEAF
We’ve recently seen that the 2018 Nissan Leaf 40 kWh is inherently incapable of practical road tripping, due to Nissan’s absurd decision to save a couple of hundred bucks by avoiding including even a basic active thermal management system in the vehicle. The management software just resorts to throttling the charging power whenever the battery gets too hot (and it does all the time at normal speed highway driving). Nissan obscured this limitation in marketing materials, but it has quickly emerged for owners in real world use, and has become a source of great disappointment for folks attempting longer drives in the Leaf (see #Rapidgate). Now that this problem is known about, Nissan will likely loose sales and revenue as a result. They may even get sued or face ‘lemon law’. How’s that for short sighted budgeting decisions?
Only with the battery at an unrealistically ideal temperature, the 40 kWh Leaf will take at least 42 minutes to charge from 10-80%, (at 45 kW initially, then tapering down to 27 kW) which will give you about 90 minutes of driving at 70 mph (covering 105 miles) in perfect conditions. However, with the battery already unavoidably getting hot from driving at these speeds, (as well as heating up significantly during the charging process itself), DC charge rates drop to 22 kWh, thus taking 80-90 minutes of charging to gain 90 minutes of highway driving even in a best case scenario. See EV superfan Bjorn Nyland’s real world experience here. Spending half your journey time charging, and having to limit your speed to 57 mph tops (as Bjorn recommends) makes the 40 kWh Leaf completely impractical for making road trips, even in a cool climate (Bjorn’s test was done in the Norwegian winter). In warm or hot climates it is worse still.
Nissan boss Carlos Ghosn is also under the belief that 186 miles of range (at 100% charge) is sufficient for EV owners (not that the Leaf can achieve even this modest range). That would typically mean real world range figures less than 60% of the Tesla figures above. Apparently Ghosn either believes road trips are a thing of the past, or that EVs will only ever be city and commuting cars. Thanks Carlos!
Chevy Bolt
2018 Chevrolet Bolt EV
The Chevy Bolt is somewhere in between the Leaf and the model 3 LR, with fairly decent highway range. A car and driver test found a 100% range of 190 miles of highway cruising range at 75 mph, with moderate HVAC settings. That’s around 70% of the highway range of the Tesla model 3LR AWD. So the car has pretty decent range. Using 90% of the battery, the road tripping range in favourable conditions could be 170-180 miles in the initial stage, and thereafter 130-155 miles when using 70% of the battery after a recharge. On the recharging side, however, while Chevy claims recharging of ’90 miles of range in 30 minutes’, in reality the Bolt will only recharge up to 37% of its energy in that time (even in ideal conditions), which would equate to 70 miles at 75 mph highway speeds (with moderate HVAC use). Perhaps 80 miles at 70 mph. A more significant problem is that the decent charging rates only occur below 52% SoC. Here is the real world DC fast charging data from Fastned:
The Chevy Bolt / Opel Ampera-e DC fast charging capability (based on Fastned’s real world data)
This tells us that when charging from 10% to 52%, a 45 kW rate is possible in ideal conditions, which equates to adding about 25 kWh, taking about 33 minutes. From 52% to 80% charge occurs at an average 35 kW in ideal conditions, adding around 17 kWh over the next 30 minutes. So to recharge from 10% to 80%, in ideal conditions, takes 63 minutes. Thus 380 mile ‘ideal condition’ trips in a Bolt at 70-75 mph require an initial stop at 175 miles for 63 minutes, then another stop at the 315 mile mark for perhaps 25 minutes before heading off again to reach the 380 mile mark. Or you could do 3 stops from 10% to 52% SoC at around 33 minutes each and get to your destination that way. Either way, that’s a total of around 90 minutes of charging, in ideal conditions. In real world conditions, such a journey seems to require a combination of adventurous spirit and patience (see this forum), traits that, whilst laudable, are not necessary in a Tesla nor in the gas vehicles folks have gotten used to. For highway trips totalling up to 175 miles then, the Bolt is great, and does have all the other EV benefits. But after the initial 175 miles, drivers have to be willing to take 30-35 minute breaks every 80 miles, or 60+ minute breaks every 130 miles. That’s an hour break for every 1 hour 45 minutes of driving. Or, better, 33 minute breaks every 1 hour and 5 minutes of driving. Both of those patterns are in ‘ideal conditions’ and neither of them anyway resemble a practical road trip for most folks. Hopefully Chevy will improve the Bolt’s charging capability in future versions.
Soon to arrive Jaguar I-Pace
I-Pace
The upcoming Jaguar I-Pace is not an affordable vehicle (compared to the Tesla model 3 LR or LR AWD) and not an efficient vehicle, and will likely have a real world range (at 70-75 mph) lower than that of the Bolt (the overall EPA rating gives it around 9% less range than the Bolt). It does promise to have better charging ability (100 kW DC capable in theory, though actual charging speeds remain to be seen). Since it has a 90 kWh battery, filling it from 10%-80% (adding 63 kWh) will take at least 45 minutes even at a 100 kW charger, so long as there is no significant throttling. The real range at highway speeds will likely be about 60% of the Tesla Model 3 LR AWD range figures above, given the relative EPA rating and the fact that SUVs struggle with aero relatively more at higher speeds (speeds that the EPA rating does not account for). That means 70% SoC of the battery will likely give little over 1.5 hours of real world driving at 70-75mph between 45+ minute charges. With slightly lower range but marginally better charging than the Bolt, the road trip readiness will no better overall – only patient adventurers need apply. It will however be a good vehicle for highway drives of up to 155 miles or so (its 90% range at highway speeds), and great if you only use it for daily commutes and regular driving. Perhaps a future version will be more energy efficient and road trip ready.
Soon to arrive Audi Quattro SUV
Audi Quattro EV
The Audi Quattro SUV will be expensive (€80k, $100k) and won’t likely be available anywhere for purchase until the end of 2018. It will have a 95 kWh battery, but its energy efficiency relative to the I-Pace’s similarly sized battery is currently unknown. The stablemate low range E-Golf is not an energy efficient EV compared to its peers (e.g. having a 28% larger battery than the Hyundai Ioniq, yet no greater range). Audi will need to do something very different if the Quattro is to be road trip ready, even with its big battery. Likely it will have a similar highway range to the less expensive I-Pace. However, that’s only 70% that of the Model X 100D’s highway range, which costs a fraction less than the Audi, so it’s hard to imagine who would choose the latter. But unlike the I-Pace, the Quattro should have better 150kW DC fast charging, which in theory will put it close to the Telsas in recharging times. The lower energy efficiency will mean it will gain less actual mileage than the Tesla for a given charge duration, however. 150kW DC fast charging infrastructure is also very rare compared to Tesla’s supercharger network. The Quattro may appeal to Audi loyalists, and might appear ..