Certain embodiments of the present invention provide a system for alerting a low battery charge condition in a jump-starter. In an embodiment, the system is portable. The system includes a first battery. The first battery is configured to provide a first battery voltage across a positive terminal and a negative terminal of the first battery. The system also includes a voltage comparison circuit that is electrically connected to the positive terminal and the negative terminal of the first battery. The voltage comparison circuit is configured to compare a reference voltage to the first battery voltage. The system includes an alert circuit electrically connected to the voltage comparison circuit and configured to generate an output signal for a speaker. The system also includes a switch configured to toggle between an enabled state and a disabled state. In an embodiment, the switch includes a stopper tap. The alert circuit is configured to cause an audible alert when the first battery voltage is less than the reference voltage, and when the enabled state is true. When the enabled state is false (or the disabled state is true), the alert circuit will not cause the audible alert. In an embodiment, the system includes a display circuit to visually indicate the first battery voltage.