Direct Current (DC) fast charging, or level 3 charging as it’s known in the Ev world, is the fastest way to charge your electric vehicle currently. This type of charging can be harmful to your electric car because the high voltages used can create thermal expansion issues and in turn reduce battery longevity if used too frequently.
Fast charging varies car to car for a bunch of different reasons but the biggest determining factor on negative effects seems to be how often it’s used. So let’s break down how DC fast actually works to get a better understanding of why this could be bad for your electric vehicle.
How Does DC Fast Charging Work?
As battery packs increase in range and size, the ability to charge them in a reasonable amount of time is crucial for adoption. For people who own Evs, charging speed is a big determinant of how their car integrates with their daily routine.
Charging relatively quickly is important and recently DC fast charging has been the solution to range anxiety.
Levels Of Charging
There are three levels of charging, all referring to how fast they can replenish your depleted battery. Charging is measured in kW (kilowatts) received, and according to most estimates, 1 kW equates to roughly 2-3 miles per hour charged.
So the higher the output of the charger, the more kW received back into your battery, the more range you get.
Level 1 chargers run off your basic 120v AC 3 prong home socket like any other home appliance. The output of these chargers ranges from 1.3 kW to 2.4 kW, so charging this way will get you between 3 and 6 miles per hour.
Needless to say, level 1 is the slowest form of charging. If you don’t have a large commute, say less than 40 miles total, an overnight charge can work well for you. Most plug-in hybrids have smaller battery packs and level 1 is totally adequate. Btw, if you’re interested in used Ev’s that don’t require much charging, check out our list of forgotten Ev gems.
For Most Evs though, you’ll probably need to step up to the next level. A Chevrolet Bolt has a range of 259 miles, at level 1 charging speeds that would take about two full days charging nonstop! So you can see how that wouldn’t work for most people.
Level 2 chargers run off 240v AC and at the minimum require something like a dryer socket. The highest output chargers require dedicated wiring with high amperage. The output speed is greatly increased with chargers ranging from 4kW to 19 kW per hour, meaning ranges of 12-57 miles per hour charged.
A Chevrolet Volt charging at the highest level 2 speeds could be fully charged in less than 5 hours. Level 2 greatly increases the usability of Ev’s but still restricts you to the range of your battery.
If you wanted to go a distance beyond your batteries range, like a road trip, you have to stop and would be stuck charging multiple hours. To make Evs truly usable faster charging was a necessity and that’s where DC fast charging comes in.
Level 1 and Level 2 chargers use Alternating current. Your Ev Battery uses DC, so it has to convert that electricity onboard to utilize it. This is what slows down charging.
Level 3 eliminates this conversion by using 480V high voltage DC. Without conversion losses, the output of these chargers ranges from 50 kW to 350 kW! A Chevrolet Bolt could charge up in as little as 15 mins but most cars throttle back the charge speeds as they get closer to full.
Tesla names its DC fast chargers superchargers because it allows their large battery pack cars to charge super fast. Dc fast chargers eliminate the range anxiety that most people fear with Electric vehicles.
How Often Should You DC Fast Charge?
To understand how often you should fast charge you need to understand what happens to the battery when you do. DC charging uses high voltage to transfer immense electricity to your battery. The byproduct of this exchange is heat and a ton of it.
Factors To Consider
An Ev battery pack is a collection of individual cells wired together to make a giant battery. Eventually, all batteries degrade as we know from experience with any electronic device.
Charging induces a chemical reaction in the battery that produces heat. The faster the charge, the faster the reaction, the more the heat.
Do this too many times and you are accelerating the rate at which your battery is degrading, which is bad for your electric vehicle.
How To Prolong Your Ev Batteries Life
Batteries are one of, if not the, most expensive parts of an electric car. Naturally, you want to make it last as long as possible. A few select habits can add years to the useable life of a battery and save you major dollars.
State Of Charge
Electric vehicles use lithium-ion battery packs which have unique advantages over other battery chemistries like the ability to be drained fully.
However, the optimal state of charge for the longevity of these battery packs is to use them between 20% and 90%. With occasional charges up to 100%.
So to extend the life of the battery you don’t want to discharge it lower than 20% and rarely charge it past 90%. This window is what lithium-ion batteries tend to work the best in.
Optimal Way To Charge
Slower charging is your friend when it comes to batteries. It reduces thermal expansion issues which we now know degrades batteries faster.
Level 2 charging at home is the most efficient way to charge your Ev. It’s fast enough that your car will be fully charged yet not too fast to cause accelerated degradation or overcharging.
Be careful not to charge your electric vehicle constantly. Say you have a short commute and your battery is 90% when you set off. When you return your battery is still at 85%, should you recharge?
You shouldn’t. Frequent charging without letting the battery drain down 20% will shorten the window in which your battery works. Think of a cell phone that’s constantly charging, eventually it loses the ability to use its capacity and drains faster. The same thing can happen with your Ev battery pack.
Minimize Fast Charging
This one is kind of a given now that you know how batteries work. You want to limit fast charging to occasional use for longer trips or when necessary.
Think over your battery as a muscle you want to work it out just enough to flex its abilities and not so hard that you damage it.
Dc fast charging can be bad for your Ev if you don’t use proper care to maintain your battery. Level 3 is perfectly fine if you develop the other habits associated with battery longevity.
What habits have you developed with your Ev charging?