Busting DC Fast Charging Myths

EV Life | 12/18/2019

Team ChargePoint
DC Fast Charging Mythbusting

So you’ve met our newest fast charger, ChargePoint Express 250, and fell in love with its sleek design and quick charge. Maybe you’re even starting to think that all your charging sessions from here on out will be fast—but hold on, not so fast! We’re here to bust some common DC fast charging myths and show you why most of your charging will still happen at Level 2 AC stations at home and work.

Fast Charging Is the Main Way You'll Fuel Your EV—BUSTED 

More than 80% of all EV charging happens at home or work. Cars spend a lot of time parked at these locations, providing more than enough time to fill up at Level 2 speeds (about 25 miles of Range Per Hour). Charging at home, work and wherever you’re already going around town is the most convenient way to fuel up on a daily basis. DC fast is useful for road trips or when you need to fill up quickly.

Secrets of DC Fast Charging

Fast Charging Is Always Better—BUSTED  

Just like humans, batteries prefer to operate at comfortable temperatures, typically in the 70s and 80s Fahrenheit (roughly 20 to 25 degrees Celsius). Fast charging delivers a lot of power, which can create heat that will “stress” batteries more than AC charging. Some vehicles also have battery conditioning designed to get batteries to the optimal temperature for charging. While heat stress has minimal impact on battery life over time, it's still a good idea to rely on Level 2 for day-to-day charging. 

More Kilowatts Are Always Better—BUSTED 

You can pile on the kilowatts, but more power won’t benefit every vehicle for a while. Most cars on the road today cannot take in the 350 kilowatts that are available at some EV charging stations out there. Each vehicle is limited in charging speed by its battery voltage and the amperage it can take, so while 350 kW is a way to future-proof charging spots, 125 kW is more than enough for the EVs of today.

DC Fast Charging in Winter

Every Car Charges at the Same Speed—BUSTED 

Every car has a different battery voltage and fast charging capacity (and most plug-in hybrids can’t fast charge at all). Each car’s battery management system tells a fast charger how much power the car can take in at a given time. The power the car can take in is limited by the battery voltage and current it can accept. In many cases, DC chargers have more charging capacity available than a vehicle can take. Charging is also affected by temperature, another reason DC fast charging curves vary over time.

Temperature Doesn’t Matter—BUSTED

As mentioned, temperature is very important to batteries. So if you’ve been driving at freeway speeds for a while, your battery will probably be too hot to charge at optimal speeds right away. Likewise, if your battery’s been sitting in the cold for a while, it’ll also charge a bit more slowly until it warms up. Remember your battery’s sensitivity to temperature and give it a chance to warm up or cool down.

While faster is not always better, never be afraid to fast charge when you need to. Let us know how your fast charge is going on social media with hashtag #ChargePointExpress—and find your next fast charge in our app!

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