Batteries as a Service for EVs and grid services: a disruptive new paradigm with a modular approach and pay per use business model. A Tender is a powerbank, which is mounted on a small trailer, rented on demand and attached to EVs for long distance trips. It’s self-mating with the car, self-steering when backing, and carries 60 kWh energy. It’s powered by a battery, a Fuel Cell or a gasoline range extender, depending on technology and infrastructure progress. Seamlessly swapping a 60 kWh Tender when depleted will take 1’: 3.6MW equivalent charging, and faster and more convenient than refuelling a car ! When stationary, the Tenders are aggregated to form a virtual powerplant, contributing to the increase of renewable electricity production (frequency regulation, buffer for charging stations, peak shaving, load shifting, etc)