The solution, provided by a Mint Linux user is to add a program called TLP.   Once installed and initialized the battery life is fine. [URL]
Latitude 3520, Running the current Mint Linux with no issues except for battery life. The laptop promises many hours of life, but if it sits unplugged with the lid closed, untouched, the battery drains to less than 10% in less than a dozen hours.    Here are the power settings in Linux. [IMAGE] I've not had this problem with previous Dells, and I'm stumped.  Almost desperate enough to contact Dell Support.  Any Linux gurus have a solution?Thanks, Barry
Latitude 3520 Linux Battery Issues