Electron-ion collisions are fundamental processes which play an important role whenever ionized matter occurs. Several merged-beams experiments reported an enhanced recombination rate beyond theoretical expectations based on the theory of radiative recombination. Experiments are proposed to clarify this situation. Three-body recombination, one additional contribution to the recombination rate, should be measured to separate this process. For low transverse beam temperatures corresponding to 10 meV this process becomes comparable to radiative recombination. Furtheron dielectronic recombination resonance near zero energy which also contribute to the recombination rate should be measured. This work will also stimulate theoretical investigations in exact calculations of resonance energies. The ion storage ring CRYRING with its cooler, providing an electron beam with lowest beam temperatures, will be the most suitable tool for this work.