Myths, Misinformation, & Misunderstandings About EV Charging & Range

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There probably is no aspect of owning an EV that is less understood or subject to more rumors, innuendos, and doubts than charging and range. At CleanTechnica, we have decided to tackle this subject head on, destroy the myths, counter the misinformation, and clarify the misunderstands once and for all. There is no charge for this service, so sit down, get comfortable, and open your notebooks. There will be no test at the end of this process, but you will be expected to share your knowledge with others so the mountains of hooey about EV charging and range out there can be eliminated.

Lesson One — EV Charging Time

Anyone who tells you a particular car can charge from a certain state of charge to a higher state of charge in a given amount of time is either lying or a fool. Why? Because there are a number of variables that affect charging speed. Here is a partial list:

• Battery size
• State of charge
• Ambient temperature
• Battery management systems
• Available charging power

Let’s take them one at a time.

1. Battery size — Every battery charges more slowly as it gets closer to being fully charged. Larger batteries, by definition, have room for more electrons than smaller batteries. That means adding enough charge to go an extra 100 miles will take less time with a larger battery than it will with a smaller battery.
2. State of charge — Every battery charges slower as it nears a full state of charge. A battery that is at 10 percent SOC will charge faster initially than a battery at a 50 percent state of charge.
3. Ambient temperature — A cold or hot battery charges slower than a warm battery. Some manufacturers — like Tesla — precondition their battery packs to warm them up or cool them down before fast charging begins. Tesla is especially good at this because its charging network is integrated with the battery management system. When a driver selects a Supercharger location, the network knows what the SOC will be when the car arrives and will heat or cool the battery to maximize the charging process when it begins.
4. Battery management system — Every EV has a battery management system that controls how fast charging occurs. The BMS is designed to protect the battery and prolong its service life. It’s not good to let the battery charge too fast if that means the battery pack has to be replaced prematurely. According to Bloomberg, the Tesla BMS starts throttling charging speeds at 20 percent SOC while Audi allows some of its cars to charge at high power all the way to 60 percent before charging power begins tapering off.
5. Available charging power — Early in the EV Revolution, charging at 50 kW of power was considered pretty good. Today, chargers with up to 350 kW of power are in use but most Level 3 chargers are around 175 to 200 kW. A V3 Tesla Supercharger is rated at 250 kW, but as Bloomberg points out, Tesla vehicles start tapering charging power at around the 20 percent SOC mark, so the 250 kW figure is largely irrelevant.

Lesson Two — EV Range

Range is another metric that people throw around a lot. Like charging performance, range can vary considerably depending on a number of factors, which makes it difficult to compare range performance between different cars.

Let’s start with this. When a manufacture says its car has a range of 300 miles, that means it should go that far if the battery is charged to 100 percent at the start and you drive until all the energy in the battery is used up. The range quoted can be misleading. Few people ever charge their cars to 100 percent largely because that last 5 percent takes forever, as explained above, and no one would drive their EV until the battery dies. That would be stupid, unless you have a car hauler following you to take the car to the next charging station. You wouldn’t deliberately drive a conventional car until it runs out of gas, so you are not going to be foolish enough to do that with an EV either.

Next, there are many, many factors that affect range. Ambient temperature is one. Cold batteries don’t travel as far as warm batteries. If the temperature outside is hot, running the air conditioner will eat up some of the available battery power. If it is cold out, running the heater will also eat up battery power. Old fashioned resistance heaters use a lot of power. Heat pumps use less, but it’s still not nothing. If you live in a cold climate and plan to buy an EV that uses a resistance heater to warm the cabin, we have a word of advice — don’t.

Speed is a big factor. The energy needed to push a car through the air quadruples when the speed doubles. Put another way, an EV needs four times as much energy to punch a hole in that air at 80 mph than it does at 40 mph. If you typically drive 85 mph on the highway every day, you will not get the range you might be expecting.

Finally, different people use their cars differently. It is common for EV owners to only charge their cars to 80 percent on a regular basis. The conventional wisdom is that NMC batteries degrade faster if charged to 100 percent on a regular basis. LFP batteries, on the other hand, do not seem to suffer degradation if charged regularly to 100 percent. Both of those statements reflect what we know so far, but be aware that the pace of innovation in battery technology is fast and getting faster. What was true yesterday may not be true tomorrow. Obviously, being able to charge to 100 percent regularly helps eliminate some of those range anxiety concerns.

Other Considerations

BYD has just announced new batteries it says can be partially recharged in 5 minutes. CATL is not far behind. Those improvements won’t affect US drivers because China is now the enemy and all things Chinese are being shunned, but for the other 192 nations in the world, their electric cars are about to get a whole lot better at this charging thing. We have often said the batteries that will be in electric cars in 2030 have not been invented yet. There are exciting times ahead for the EV revolution, which is really just getting started.

Here is another tip for EV drivers, especially those in cold climates — pre-conditioning. Almost all EVs allow you to set the interior temperature and desired battery temperature while plugged in to a home charger. That way, the electricity needed to hear or cool the interior and the battery comes from the wall outlet, not the battery. That means more energy is available to drive the car, which translates into more range.

Final Thoughts

EV manufacturers in general do a poor job of educating their customers about how their electric cars are different thanfromconventional cars. It is fair to say that an EV may not be the right choice for every driver. Not everyone wants to drive a Miata or an F-350 dually diesel, even though both technically fall into the definition of an internal combustion vehicle.

Those who drive electric cars are pretty happy with them. They like the instant torque an electric motor provides, the silent ride, and the ability to come to a stop without using the brake pedal. They like being able to charge at home and never having to go to a smelly gas station again. If those things appeal to you, great. Welcome to the EVclub. But take time to learn about charging speed and range so you are prepared to get the most out of your EV experience.