Potential energy functions for a set of experimentally characterized electronic states of NO2+ and N-2(2+) have been calculated using a series of correlation consistent basis sets ranging from cc-pVDZ through to cc-pV5Z. By exploiting the convergent properties of the correlation consistent basis sets, complete basis set limit approximations of each calculated point on the potential energy surfaces can be extrapolated in a simple fitting procedure. The resultant complete basis set approximated potential energy functions are able to yield very accurate spectroscopic constants outperforming the pure ab initio potentials in reproducing experimentally determined data.