For plug-in models, reserves are a function of the battery’s capacity and range. The question of how long an electric car stays charged depends on your driving habits.
Using the Tesla Model 3 Standard Range Plus again as an example, its stated capacity is 24 kWh per 100 miles with a range of 250 miles. But driving in hilly terrain and extreme temperatures, braking frequently and using the air conditioning can all significantly dilute this figure. These factors can impact EVs even more than ICE cars.
Also, an automaker’s stated battery capacity isn’t necessarily the available usable capacity. An internal monitor prevents the battery from being fully charged or wholly depleted to preserve the battery’s lifespan and fuel efficiency. In other words, there may be only 60%–70% of power available to use.