An Irish-American billionaire who kept his philanthropy secret for 15 years has given away $7.5 billion – and plans for it all to go to charity before his dies.

Chuck Feeney, 82, wears a $15 Casio watch, often travels in coach, does not own a car, is a self-confessed ‘shabby dresser' and sensibly made his children work their way through college.

"I believe strongly in ‘giving while living,'" said Feeney in 2012. "I see little reason to delay giving when so much good can be achieved through supporting worthwhile causes today."

He has given away 99 percent of his fortune to health, science, education and civil rights causes around the world through his Atlantic Philanthropies foundation.

In 1984, Atlantic Philanthropies received all of the Feeney interests in Duty Free Shoppers and operated anonymously for its first 15 years. Some of his biggest contributions went to rebuilding Vietnam's health care infrastructure after the war, building the Republic of Ireland's university system, and biomedical and cancer research.

In his biography,The Billionaire Who Wasn't: How Chuck Feeney Made and Gave Away a Fortune Without Anyone Knowing,  Feeney said, "I had one idea that never changed in my mind—that you should use your wealth to help people."

(READ more in the Daily Mail)