. . . Jeff Dahn states that charging to a level below 100% can have a large impact by reducing the rate of degradation of the battery.
Most people don’t use their entire electric vehicle battery pack capacity every day, and rarely have the need to charge all the way to 100%. By charging a lithium-ion battery to 80%, the lifetime of the battery can be as much as doubled, according to Grin Technologies. This Canadian company performed such tests while developing an adjustable charger designed for electric bicycles and other light electric vehicle batteries.
It is important to note that the most damage from high charge levels comes from when the battery rests at such high levels for long periods of time. I’ve heard of many people who freak out after learning about the effect of high charge levels, with some swearing off 100% charging forever.
But 100% charging isn’t a big deal in small doses. If you are planning a long trip and will be heading out shortly after you finish charging, a 100% charge will have very little impact on your battery’s lifespan. However, if you will be leaving your battery unused for many days or weeks, a charge level of between 30-60% is much healthier for the batteries over the long-term.
Does this apply to all lithium batteries?
Theoretically yes, though LiFePO4 batteries aren’t quite as affected by high charge levels as the rest of the lithium-ion lineup. But generally speaking, these rules apply to all lithium-ion batteries from your electric car to your cell phone and even your electric tooth brush. Professor Dahn even jokes that you’d be well advised to keep your laptop in the fridge when you’re not using it, if you really want to get extreme about increasing your battery life.
For the most part, these simple methods can greatly increase the lifespan of your battery, and are easy to implement. Avoid supercharging your electric car unless necessary. . . .