Should I Charge Overnight? Should I Charge Every Night?

This is a great question, and generally, the answer is YES!

The first reason that you should plan to charge overnight is based on laboratory science and lithium ion best practices: limiting depth of discharge. Depth of discharge is the amount of battery charge you use before recharging. In a battery's "ideal world," you would keep the depth of discharge very small and centered around 50% state of charge. For instance, you would charge 51%, and only go down to 49% before recharging. 

However, this is not a practical way to use your EV and will likely not make a big difference in the lifecycle of your battery. Instead, Recurrent recommends keeping your battery's state of charge between 80% and 30% for daily use, if you need 50% of your battery's range for daily tasks. If you want to be conservative, or if you don't need that many range every day, you can limit it even further to 70% and 40% -- or whatever works for you.

Another reason that you should probably charge overnight is because electricity rates are generally cheapest in the wee hours of the morning when demand is lowest. Additionally, many utilities offer special rates for EV drivers to recharge.

A Few More Perks to Overnight Charging Include:

• Overnight charging likely means charging at home using a level 2 charger. This is the most "battery friendly" speed to charge your car, rather than relying on public fast charging (which is also more expensive)
• If it's cold or hot where you are, your battery can use energy from the grid to maintain an ideal battery temperature when it's plugged in. Many EVs have different thresholds for battery conditioning when plugged in vs. unplugged.
• Similarly, if you charge overnight, you can use energy from the grid to precondition your cabin before you get in your car in the morning. It's a great way to keep it toasty warm - or cucumber cool - without depleting your range.

One Caveat: if you're not actually driving your car every day, you may not need to plug it in every night. This will depend a lot on how much electricity your car's auxiliary services use. Cars like Teslas that run Sentry mode, for instance, may still use quite a bit of energy even if they are not being driven. On the other hand, cars like Nissan LEAFs don't have an easy way to set a charge limit, so it's not easy to stop the charge at 80%.