Can I run 12v dc led lights with 15v dc?

Running 12V DC LED lights with 15V DC is generally not recommended, as the higher voltage can lead to overheating, reduced lifespan, or even damage to the LEDs. Most 12V LED lights are designed to operate within a specific voltage range, and exceeding that can cause them to draw more current than they are rated for. If you must use a 15V supply, consider using a voltage regulator or a buck converter to step down the voltage to a safe level for the LEDs.