One question we get asked often at E-Flux is: How can I charge my car without damaging the battery? We have all encountered that smartphone with a 'lazy' battery that runs out quickly and of course we want to protect our expensive EV against that type of decay. If you're nice to your battery, it'll be nice to you and keep you going for a long time! So how do you prolong your battery life?
When we speak of battery capacity vs charge point capacity this ratio is expressed in terms of 'C'. When you charge an EV with a battery capacity of 60kW with a fast charger that has a capacity of 60kW we're dealing with a ratio of 1C. In this example, a charger with a capacity of 120kW has a ratio of 2C an a charger with a 30kW capacity has a 0,5C ratio.
To preserve a high quality battery it is recommended to frequently use chargers with a 0,5C to 0,85C capacity compared to the EV battery and to abstain from chargers with a capacity of 1C and more as much as possible.
If your car battery has a capacity of 22kW, your 1C is reached once you charge your car with a 22kW charger, which means you'd do well to avoid fast chargers with higher capacity as much as possible.
The duration of the charging sessions play an important part as well when it comes to preserving your battery life. Small, frequent charging sessions keep your battery healthier than going from empty to full in one long stretch. This is due to the chemical composition of which the battery is composed. When the battery is charged for a longer period of time, it will heat up; this heat has a negative impact on the chemical composition of your EV battery.
In conclusion: you're better off charging small amounts on a daily basis. Try to find a charger with a capacity ratio between 0,5C and 0,85C compared to your EV battery. Keep track of the temperature of your battery; make sure it doesn't heat up too much. Your battery will thank you!