Electric Vehicle (EV) Battery functions by allowing ions to move between their negative and positive electrodes. The optimal operating point for lithium-ion batteries occurs when they are charged to approximately 50%. Ions distribute evenly at this level which reduces stress on the internal structure of the battery.
The Impact of Extreme Charging
When batteries are charged to 90% or 100% levels, one of its electrode experiences ion crowding. These overcrowded electrodes create physical swelling together with chemical reactions which generates cracks and crystal formation. Consequently, this process permanently removes lithium from the charge/recharge cycle, reducing the battery’s overall capacity. Similarly, when the battery reaches near-empty state the resulting voids lead to structural collapse.
Even during fast charging especially through high-voltage DC chargers makes ions move faster than they can properly settle into stable electrode positions. This fast ion movement produces substantial heat which again speeds up the degradation process. Therefore, adhering to the 20–80% rule remains a prudent strategy. Also, leaving the battery at 50–60% charge for extended periods when maximum range is not needed helps prolong its life.
Notably, lithium iron phosphate (LFP) batteries represent an exception. These batteries tolerate 100% charges better than other chemistries.
In essence, treat your EV battery with care. Avoid extreme charging and rapid charging whenever possible. By doing so, you maximize your battery’s lifespan and ensure optimal performance.
Reference- Science Today, Popular Science, Scientific American, New Horizon