Making the case for more range in electric vehicles
Preface
I hear a lot of people look at 100 mile EVs and say "pffft, that's more than enough!", and "the average American commute is only 30 miles!". Today I intend to explain why that's irrelevant, and why you should probably aim for 2-3x what you think you need.
Usecase
First of all, your "average daily commute" is completely irrelevant in the context of maximum available range. Nobody is worried about range when going to the store and picking up groceries or commuting back and forth to work, they care about it when driving hundreds or thousands of miles at ~70MPH, as that is when they are going to be using the full capacity of their batteries. Many people may not realize or consider that most range estimates are calculated under near-optimal conditions. What we’ll be discussing here are the items that they do not account for (that’s not to say that they should, necessarily, as there are lots of variables). This is not intended to be a comprehensive scientific study, but rather to give you some basic considerations when deciding how much range you need for your EV.
Lower limit
You don't want to drain the battery below 10 percent. This is both bad for longevity, and also will make you, the driver, very very anxious.
Charging speed
You might see that your vehicle has 250kw+ or 400 miles/hour charging and think that's plenty, but what you may also not realize is that that is the peak charging speed you'll only reach at near-zero %. Depending on the vehicle, charging speeds may drop off dramatically and immediately, like within the first few percent. Regardless of vehicle, the charging speed will decrease gradually as the battery charge increases but the rate at which is does varies from one vehicle to the next. In particular 800-1000V batteries are less susceptible to the impact of this. Here's an example of the charging curves for a few different vehicles:
Having a larger battery means you retain these faster charging speeds for longer.
Upper Limit
Most vehicles will severely limit fast-charging (level 3) rates when >80%. While many vehicles may have a maximum of 150kw+, these rates can often drop down to <50kW once exceeding this threshold, so most drivers will depart upon reaching this level.
And beyond that the car becomes less efficient at 90%+ charge since your regenerative braking can be reduced or even completely unavailable.
Cold/hot weather
You'll probably want to also drive your car when it's cold. Cold weather not only limits the capacity of your battery, but limits regenerative braking, and also increases consumption due to air density and cabin heater use. Some EVs are equipped with heat pumps that greatly decrease heater consumption by 300%, but these are still quite rare on EVs, as they're a large investment and make a relatively small impact in the overall range.
The delta between ambient temp when very cold and “comfortable” temperature is much larger than it is when very hot. For example, a very cold day might get into the 30s (fahrenheit) or less, where a very hot day will reach up into the 100s. So assuming a ~75 degree comfort level, that’s a 45 degree delta in the “cold” and a 25 degree delta in the “hot”. Thermodynamically, this is an enormous increase in required energy to keep the cabin comfortable.
Obviously this will vary depending on a lot of factors but often times this can be upwards of a 30% loss in range.
In places where it is particularly cold outside, you may encounter snow, leading to increased rolling resistance and decreased efficiency and range. This will compound on the effects of the cold.
In hot weather, you'll also increase A/C consumption. Cars, naturally being full of Windows everywhere, suffer from the greenhouse effect, and also don't usually have a ton of insulation, so they don't usually have super efficient cooling systems.
Also when charging, this will require more energy to cool the battery itself, which can further limit charging speeds.
Degradation
After 100k miles, you can probably expect ~10-15% range loss due to battery degradation, so if you plan to keep the car for a long time, that’s something you need to account for. If you don’t plan to keep the car for a long time, this is something you can expect to impact your resale value.
Detours
While charging stations are still being added, they’re doing so largely at a snails’ pace (especially the non-Tesla ones) and there are still areas that won’t have sufficient charging, and you’ll have to take large detours to reach. Having a larger battery allows you to take a more direct route with fewer chargers.
If you’re using a non-Tesla charger, you should probably also plan to charge before you need to, because there’s a good possibility the charger you plan to use won’t be working when you arrive, and you’ll need sufficient charge to reach the next one.
Wheels
Want a cool look for your hot ride? Wheel turbulence has a significant impact on efficiency. This is why many high efficiency vehicles, such as the Aptera, Honda Insight (the old one), and Honda Clarity will keep them covered entirely. Simply removing the aero caps from your Model 3 will cause ~4% range loss. You can probably expect something similar when opting for the stylish wheel option in your build configurator when ordering.
Tires
Many high efficiency vehicles today come equipped with low rolling resistance (LRR) tires. They increase efficiency (and longevity) by using a harder compound. But this is not without downsides. They also have poorer traction, especially in wet weather. These are, in my opinion, an unsafe and unwelcome compromise. They’re not good for cars that are remotely sporty, either. If your vehicle comes equipped, and you want to switch from LRR to some more common, softer, stickier, and safer compounds, this will result in a considerable loss of range.
Rain
Driving in the rain can cause a ~15-20% loss in efficiency and range.
External cargo (roof/hitch)
Want to load up some bikes, camping gear, a trailer, or literally any sort of external cargo? That's further decreased aero efficiency and more lost range. Minimum of 30%. Upwards of 60%+ if you’re pulling a trailer.
Optimistic range estimates
Most EPA ratings are based on mixed use driving. As I alluded to in the intro, you're probably not concerned about city efficiency when looking at total range. You're probably more concerned with how far it can go at a steady 70MPH. EPA ratings can vary pretty wildly against "real world" tests, so be sure and research ratings for your vehicles of interest. Teslas are notoriously overrated vs. other brands, and German brands are often underrated.
V2x
This is not terribly applicable today, as the vast majority of cars and homes are not equipped for it, but the near future holds potential for that extra battery capacity to be used for what is collectively and colloquially known as "V2x", where x is a variable:
- V2H = vehicle to home (powering your home off-grid, using your EV's batteries)
- V2G = vehicle to grid (to charge the vehicle during off-peak hours, and sell energy back to the power company during peak periods, offsetting grid load)
- V2L = vehicle to load (powering other devices directly from the vehicle, like heaters, A/C, table saws, welders, etc.)
This allows you to make use of the additional battery capacity that you won't be using probably 95% of the time.
Some vehicles can be equipped with 100kWh+ batteries. This is enough to run an entire home for several days. This can be extremely useful in the turbulent years we will likely continue to experience in the near future due to climate change. But be aware these additional cycles will accelerate battery degradation.
You can also use this to buy/sell electricity from the grid for profit, helping to offset the expensive initial cost of the vehicle, as well as improving the cleanliness, efficiency, and stability of your local "grid".
The only vehicle I know of that currently supports this is Ford with their "Pro Power Onboard".
Conclusion
While you’ll never encounter all of these factors at once, you should consider and account for which and how many of these factors will affect your use, and probably give yourself a little extra breathing room, if you have the means.
Now don't get me wrong, I also think >400 mile range is probably excessive. As EVs continue to increase in popularity and availability, the biggest need is going to be more charging stations. Most gas cars only go ~300 miles, and we're getting to the point where you can recharge your car nearly as fast as you can fill up a gas tank.