Q: battery drain

The stereo would only be a problem if it draws so much power that it overwhelms the alternator, thus preventing the battery from being properly and consistently recharged. That would be unusual as most car stereos do not use a lot of power. A mechanic can measure the total demand on the car’s electrical system, as well as the individual stereo, in order to determine if the current draw is too high. If the battery is being drained, due to current flowing in a circuit even when the circuit(s) has been commanded off, that is referred to as a "parasitic" load, sometimes know as a phantom load, too. Utilizing the factory wiring diagram, a Mechanic would use an ammeter to test vehicles circuit, segment by segment, until the parasitic load is found. If you want these steps performed by a certified Mechanic, dispatched by YourMechanic right to your location, please request an electrical diagnostic and the responding certified mechanic will get this resolved for you. If you have further questions or concerns, do not hesitate to re-contact YourMechanic as we are always here to help you.