If the battery health of your iPhone 8 is at 81%, it indicates that the battery capacity has degraded over time. Here are a few steps you can take to help maintain the current battery health and potentially prevent it from decreasing further: Optimize battery usage: Adjust your device settings to maximize battery life. Enable features like Low Power Mode, reduce screen brightness, and turn off unnecessary notifications or background app refresh. Avoid extreme temperatures: High or low temperatures can impact battery performance. Try to keep your iPhone within the recommended temperature range (0°C to 35°C or 32°F to 95°F). Limit battery-draining activities: Minimize activities that heavily drain the battery, such as playing graphically-intensive games or running multiple apps simultaneously. Be mindful of power-consuming tasks to preserve battery life. Charge your iPhone properly: Use the original charger or a reputable third-party charger to charge your device. Avoid overcharging or letting your battery drain completely before recharging. It's generally recommended to keep your battery level between 20% and 80% for optimal longevity. If you decide to replace the battery, it can help restore your iPhone's battery health to a higher percentage. Apple or authorized service providers can replace the battery for you. Just ensure that you choose a genuine battery replacement to maintain device integrity. It's worth noting that as batteries age, some level of capacity degradation is normal. If you experience significant battery life issues or further decline in battery health, it's recommended to consult Apple Support or visit an authorized service provider for further assistance.