Fast charging infrastructure is widely acknowledged as necessary for the market success of electric vehicles. However, fast charging requires cost intensive infrastructure and grid connections. Accordingly, the risk of sunk cost is high, although fast charging infrastructure might be profitable in the medium to long term. In addition, the demand for fast charging varies greatly and the maximum power of charging stations may only be needed for a short time period per week. Although the profitability of stationary storages and the demand for fast charging have gained broad attention in literature, the specific question of how and under what circumstances stationary batteries can increase the profitability of fast charging stations has not yet been addressed for all potential applications. Here, we analyze the extent to which stationary storages can increase the profitability of fast charging stations by reduced grid connection costs on the one hand and additional revenues from intraday trading of electricity on the other hand. We compare different battery technologies and distinguish two use cases: fast charging in cities and along highways. Our results indicate that the profitability of a stationary storage installed together with a fast charging station depends on various parameters. While for a city fast charging station, intraday trading might lead to lower cost, this is not the case for highway stations since the heavy use motivated by intraday trading can significantly shorten battery life. Our results underline the importance of second life batteries since low-cost batteries have a significant impact on the system’s profitability.