Why do some fast chargers have a battery?

Peaks of demand are short. A battery charges slowly from a small grid connection and discharges quickly into cars, so a site can offer high power where the grid cannot yet.

Explained in

Battery storage · Stop 01Why put a battery next to a charger?A weak grid connection, short peaks of demand and a battery that fills the gap: why some charging sites store energy before they sell it.

This site needs its full power only when cars arrive, and then for part of each session. A grid connection sized for those peaks costs more, because the one-off contribution follows the connection's power, and it stays mostly unused; here, a larger one would also have taken years. A battery turns a small connection into a large one for short periods: it charges slowly from the grid and discharges quickly into cars.

From “Peaks are short, connections are expensive”, stop 01
  1. Are battery storage systems safe?EU law requires stationary systems to be tested for the safety parameters of Annex V of the Batteries Regulation, ten tests from thermal shock to fire, with the emission of gases considered throughout, and to document further hazards and their mitigation.
  2. What is a battery passport?From 18 February 2027, EV batteries, batteries for light means of transport and industrial batteries above 2 kWh need an electronic record with information on the model and the individual battery.
  3. How does a site battery plan its day?From a demand forecast, the grid limit and the day's prices, hour by hour, with four rules in order: never below the floor, cover the peak, keep the reserve for the next peak, then follow the price. The deep dive shows one day's plan.
  1. Bundesnetzagentur: Positionspapier zur Erhebung von Baukostenzuschüssen, Beschlusskammer 8, 20 November 2024: the contribution follows the connection's power. https://www.bundesnetzagentur.de/DE/Beschlusskammern/BK08/BK8_06_Netzentgelte/70_BKZ/BK8_BKZ.html. Checked 13 Oct 2026.