The battery life of cordless inflators varies depending on the model, usage, and charging frequency. Generally, a fully charged battery can last for about 15 to 30 minutes of continuous use, which is enough to inflate 4 to 8 tyres. However, you should always check the battery level before using a cordless inflator and charge it when it’s low. You should also avoid overcharging or undercharging the battery, as it may affect its performance and lifespan.