This paper presents experimental results of Thermal Energy Storages (TES) implemented into a liquid cooling system for the cooling of power electronics (PE). The experimental investigations are performed on a test rig at Hamburg University of Technology. The main objective of this study is to find a constellation, in which the weight of the liquid cooling system can be reduced by complying with a maximum temperature. For this purpose tests with a Latent Heat Storage (LHS) and a Sensible Heat Storage (SHS) were realised. The results are compared to a direct cooling of power electronics. Finally the weight reduction potential is estimated.