A theoretical study of the lithium intercalated LixV2O5 System has been performed using a dual approach, based on A initio calculations and experimental data. Two main aspects have been investigated: the atomic structure of each phase and the voltage of a lithium battery with a positive electrode made of LixV2O5. This approach leads to proposal of the full atomic arrangement for the different phases obtained during the reaction. Particularly, a structural arrangement is proposed for the debated omega-Li3V2O5 phase, based on a full simulation of its X-ray powder diagram. For the first time, an antiferromagnetic ordering is envisioned for xi-Li2V2O5. Finally, a very good simulation of the experimental open circuit voltage (OCV) curve of the battery, from x = 0 to x = 3, is obtained when the magnetic interactions are considered