I am working on a project that uses an Arduino Mega along with 2 12V solenoid valves and 1 12V Bilge Pump as well as some ultrasonic and temperature sensors. I would like to use the Mega to simply activate one of the valves and the bilge pump, not necessarily at the same time. What I'm having trouble figuring out is how to incorporate a 12V Lead Acid Battery to power the arduino, pump, and valves all at once. I understand that directly wiring the arduino to the battery will ultimately fry the 5V regulator on the arduino.
Which leads to my question: How can I use a 12V Lead Acid battery to power the arduino, pump, and valves without harming the arduino itself? All help appreciated!