Batteryminder is a free Android application developed by Rollerbush, designed to help you keep track of your device's battery life. It provides you with a detailed view of your current battery level, including the percentage indicator in the status bar. The app also allows you to set customizable remaining time estimates based on your device's historical battery information. You can receive low battery alarms to ensure you never run out of power unexpectedly.

One of the best features of Batteryminder is its minimal power drain. It doesn't consume much power while it's running in the background, making it an ideal application to have on your device without worrying about its battery consumption. You can also customize the notification content to show estimates, charging status, temperatures, health, voltage, and more.

It's important to note that Batteryminder doesn't allow external storage (SD) installation due to the services, alarms, widgets, and auto-start functionality involved. The app bases remaining time estimate calculations on battery status reports gathered from the Android system. Therefore, it takes time to become more accurate and less fluctuating. Clearing the battery data history will force time estimate calculation to start over from zero, with much lower accuracy.

Overall, Batteryminder is an excellent application that helps you monitor your device's battery life, ensuring you never run out of power unexpectedly.