Dr. Balcells was born in Barcelona on 31 March 1922 into a noble family. He began his high school studies at the Maragall Institute of Barcelona and completed them on 1939 at the Sant Isidoro Institute of Seville, the city where his family had moved to given the political convulsions of the period due to the Spanish Civil War.
He finished his pharmacy studies in 1932 at the University of Barcelona. He was the president of entomology section at the Museu de Ciències Naturals de Catalunya (1932-1935) and of the Museu de Zoologia de Barcelona (1935-1939). He was also a technician of the Institut Municipal de Ciències Naturals de Barcelona and of the Museu de Zoologia (1941-1966), where he became director in 1966 until 1967.