Powering an Arduino, Pump, and Solenoid Valve with 12V Lead Acid Battery

Hello All!

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!

Use a $1.00 buck converter if you are worried the 12V might climb too high when charged.

Set the converter to say 9V and feed it into the RAW terminal.

Feed your pump and valve via mosfets directly off the lead acid battery.

Ultra sonic and temp sensors come off the arduino 5V as long as they do not pose too much load on the spec levels.

This link below is just 1 example of many......

https://www.ebay.com.au/itm/5V-9V-12V-Voltage-Regulator-Buck-Converter-Power-Module-Integrated-Circuits/123483359931?epid=13025753764&hash=item1cc02e8abb&enc=AQADAAADAFjVrDbVsZ8oH%2F8PNHtt9VX4%2Fw7FZcmMuqsX8uaFEduVxcpikqRKjbzUqC89kUFhS4aqjCBb%2FWbJ8GJ%2BoFTbL844Ew370XJdNmcQxFTgwqQNn1lI%2FQYOSeO8Hjo649cm8%2BGfNk4Rl73Zv1iakJHfS%2FTPQAspSipKFY1Tx9ruj0aJr4xZVkbq%2BvU8cM0Gx4X7ienS%2BRcKUAQW%2FJa4O%2FFxlGxmlVHr0inOZz6U%2FLwUT83vxy1EWcenRMyFBw1CRHLs4DZZ8861qCzsDvvnuhW2VNZAZ9Y7IUQlUO65yrP1xPtgaCUjZWV5Btm9ZL46pfbkAXnhqaL5RqFZoC8CugLiihmR6tTq3Wql2mzb16iRdjN7KrHpt9ag6sBaXiTLiC4Bj4ymovAtNWYBD5f%2Boyhy9fICaO2AnNy7UVDaaiSoBjz679y%2FkDCchYzQ1eLofZhWuP4VAw8%2FzaBjErK7w6vwZCw%2FPaUdTZgJXIX%2FFjXA0nDGLeP0iKxmw28o8N5t1ZMPuZ0b1rYbUUenzI0QwNVLn3v0YMOPqlNVxa9ne7nuhP09V0P1bWzOvHL%2FQH9cfBV3SsbM4H51r5vjJRhtNqXvqVSqxl2b%2Fh9YdRa497IFte%2BXbouzZyIbe23EBgpspZPOf778zeHEewVTj4iCtrH8w51TVOX3gCXNDp9u%2FzI4aRz%2BiQwdaWcm4Goi6HEtbnn37hwdJoKwQa3ljLF%2BDP%2B%2FNVHrAbuFjtWq27S9Vcre8KL7L3yYbzkKeGK4a%2Fs5bPn4%2FICFBQ1zVcSLWw1QynR1z03LAlviuacYYt6zws4nksjIE12hj3oReQHg%2BVMv3ek%2B5aGNTrTQFOeZ8yIoMqTvQt%2BWfBYtUX5dh1At8evlxoo4YHwjSRHLyCYAXJOwMpRwB%2Blx4tKI%2FBiA2KZM6aKkmYiOCcc2FgTlRznxhEzi6Rsz0X0C3QY0OYf7IYIsmOzA9rMzo9koKuV9L8XgKq7%2F7PvAAnGlwTjZHQMAxYmYHAqqAOxCSSki6aboihuysPvhRw%3D%3D&checksum=123483359931fb330c6f608246a6b717be4ffe0d7c98

I recommend to avoid eBay and use a high quality step down voltage regulator from Pololu to produce 5V for the Arduino. That way you avoid the wimpy, inefficient on board linear regulator, and you don't need to worry as much about motor-induced voltage spikes in the 12V power lead.