Despite his father's good standing, he had made unsuccessful financial speculations, had lost all his money and moved from Paris to Montpellier. Coulomb's mother remained in Paris but Coulomb had a disagreement with her over the direction his career should take so he left Paris and went to Montpellier to live with his father.
Sa kabila ng kanyang ama mabuting kalagayan, siya ay ginawa nabigo sa pananalapi speculations, ay mawawala ang lahat ng kanyang pera at inilipat mula sa Paris sa Montpellier. Coulomb ng ina naiiwan sa Paris ngunit Coulomb nagkaroon ng hindi pagkakaunawaan sa kanyang higit sa direksyon ng kanyang karera ay dapat tumagal kaya siya sa kaliwa Paris at nagpunta sa Montpellier upang manirahan kasama ng kanyang ama.