This work is the second one in a series of papers on the correlation of etched particle tracks with the projectiles' electronic energy transfer. The plastic detector CR39 was bombarded with boron and lithium ions at different energies, and subsequently etched. The relation between the diameter of etched tracks and the projectile energy was studied in detail. Maximum diameters were found after boron irradiation at 2.1 MeV, and after lithium irradiation at about 1.1 MeV. These values closely coincide with those ion energies at which they deposit their maximum electronic energy in the target surface area. The observations also point at a linear relationship between the maximum electronic stopping power and the atomic number of the projectile ions.