Handheld charge indicator assemblies, children's ride-on vehicle kits including the same, and methods of determining the state of charge of a battery assembly of a children's ride-on vehicle. Handheld charge indicator assemblies are sized to be held in the hand of a user and are configured to be selectively interconnected to a battery assembly of a children's ride-on vehicle and output an output signal representative of a voltage of the battery assembly. Handheld charge indicator assemblies include a body, an electronic circuit housed within the body, an indicator configured to output an output signal representative of an input voltage to the electronic circuit, and a battery connector configured to engage the battery assembly of a children's ride-on vehicle. In some embodiments, the handheld charge indicator assembly further includes an actuator configured to actuate the electronic circuit to detect the input voltage responsive to a user engaging the actuator.