Q: voltage warning light still coming on 30-45 seconds after car starts.

Nothing should be replaced until you have in hand a definitive diagnostic pinpointing the faulty segment of the car’s electrical system. There may be too much voltage drop in the charging circuit, as well as elsewhere, but start with the charging circuit. The faulty segment could be anywhere, so using the factory wiring diagram you just have to methodically and systematically test the entire charging circuit until the fault is found. It’s laborious but compared to replacing parts that might be perfectly good, properly diagnosing the fault will save you money and time in the end. As far as the engine warning light, at the moment I would fix the issue with the charging system first because that may resolve the check engine light. If it doesn’t, just request a check engine light diagnostic. If you want the charging circuit diagnostic steps performed by a certified Mechanic, dispatched by YourMechanic right to your location, please request a charging circuit diagnostic and the responding certified mechanic will get this taken care of for you. If you have further questions or concerns, do not hesitate to re-contact YourMechanic as we are always here to help you.