What happens inside the battery
Inside an electric vehicle battery, chemical reactions occur during charging and discharging. Over time, tiny particles of the battery's material break down and lose their effectiveness. The positive and negative parts of the battery, called electrodes, gradually degrade as ions move back and forth through a chemical substance called an electrolyte. This process causes the battery to hold less charge and deliver power less efficiently, similar to how a worn-out rechargeable flashlight battery doesn't last as long as a new one.
How charge cycles affect batteries
Each time you charge and discharge a battery, it completes one cycle. Every cycle causes slight damage to the battery's internal structure. Modern EV batteries can handle hundreds of thousands of cycles before serious problems develop. However, the more cycles a battery goes through, the faster it degrades. Fast charging creates more stress on the battery than slow charging, so using fast chargers frequently can speed up degradation.
Temperature's role in degradation
Heat is one of the biggest enemies of battery lifespan. When batteries get very hot, the chemical reactions inside speed up and cause more damage. This is why electric vehicles in hot climates like Arizona or Florida may experience faster battery degradation than those in cooler regions. Even cold temperatures can affect batteries, though differently. Cold doesn't permanently damage batteries, but it temporarily reduces their performance and range until they warm up.
Signs of battery degradation
As an EV battery degrades, owners may notice reduced driving range, slower acceleration, and longer charging times. The car might not go as far on a full charge as it did when new. Some vehicles display battery health information on their dashboard. Most modern EV batteries still retain 80-90% of their original capacity after eight years, so degradation is usually gradual and doesn't affect most drivers' daily use.
Extending battery life
EV owners can slow battery degradation by avoiding extreme temperatures, minimizing fast charging when possible, and not letting the battery completely drain regularly. Parking in shaded areas, using battery preconditioning features in winter, and charging to 80% instead of 100% for daily driving can all help preserve battery health. Most manufacturers design their cooling systems to protect batteries from overheating during normal driving. 
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