Electric Vehicles Want to Wrap-Up Warm Too

As winter settles in, and we huddle inside readying ourselves for the Christmas feast soon to come, electric vehicles feel the chill too.

Like humans, EVs work best when they’re in the perfect temperature. More specifically, their batteries do. Charging a lithium-ion battery at below 0 (Celsius) temperatures causes permanent damage. A metallic lithium plate forms on the anode, something you won’t be aware of until you overcharge the battery. And boy will you know about it after that.

Discharging li-ion batteries is a lot more flexible, however. While charging temperatures should fall within 0°C and 40°C, discharging temperatures are fine within -20°C to 60°C.

And within these magic temperatures of operation, there are of course optimal temperatures. Around 20°C is ideal for charging and discharging.

So what effect does Jack Frost have on EV battery performance?

At lower temperatures, battery capacity decreases overall. At the extremes, this translates into as much as 50% less capacity! Not only that, but don’t forget you’re also using some of that charge to warm the interior.

Low temperatures also effect voltage, of course. Anyone that’s tried to start a combustion engine in freezing weather can attest to that.

Thankfully, this is well understood by manufacturers, so this pesky obstacle of physics doesn’t hit as hard as you might first think. Once the battery is up to a cosy temperature, capacity returns to normal.

So as long as the EV is warmed up as well as you are, it’ll be much happier to go further.

• • lithium ion
  • Charge at 0 to 45
  • Discharge at -20 to 60
  • Higher temp gives good C/DC performance, but shorter battery life
  • 2.33V per cell 15C
  • 2.3V