Why put a battery next to a charger?
A rural fast-charging site on a trunk road. Two chargers of 300 kW each, but the local grid offers only 200 kW.
Behind the chargers stands a container: a battery of 400 kWh that can deliver 400 kW.
The questionWhy build a battery instead of a larger grid connection?
Guess firstTwo cars at 300 kW each, a grid connection of 200 kW. How much power must the battery add at that moment?RevealHide
400 kW: 600 kW of demand minus 200 kW from the grid. The battery refills from the grid when demand is lower.
A composed day. Above the 200 kW line, the battery supplies the difference; below it, the grid alone charges the cars and refills the battery.
Peaks are short, connections are expensive
A fast-charging site needs high power only when cars arrive, often for a few minutes per session. A grid connection sized for those peaks costs a lot, may take years to build in rural areas, and stays mostly unused. A battery turns a small connection into a large one for short periods: it charges slowly from the grid and discharges quickly into cars.
- Weak grid: high power where the grid cannot provide it yet.
- Peak charges: in tariffs that bill the highest draw, a lower peak saves money.
- Time: a battery can be installed while the larger connection is still being planned.
Rural roads still need chargers
Along the core network, EU law has required of at least 400 kW every 60 km since the end of 2025, rising to 600 kW by the end of 2027. Where the grid is weak, batteries are one way to offer that power before the grid catches up.
Check your understanding
3 questions. Answer all of them to complete this stop. Each answer explains itself.
Two cars draw 600 kW, the grid offers 200 kW. What must the battery supply?
Demand minus grid: 600 − 200 = 400 kW.
Why can a battery replace part of a larger grid connection?
The battery charges slowly between peaks and discharges quickly during them.
When does the battery refill?
Whenever the chargers need less than 200 kW, the rest of the connection refills the battery.
- Charging pool AFIR's term for one or more charging stations at a specific location, counted together for the targets along the main roads. Charging infrastructure, stop 01 Glossary
- TEN-T The trans-European transport network, the EU's main roads and corridors, divided into a core and a comprehensive network; AFIR sets charging targets along it. Truck charging, stop 05 Glossary
- EUR-Lex: Regulation (EU) 2023/1804 (AFIR), Article 3. https://eur-lex.europa.eu/eli/reg/2023/1804/oj. Checked 09 Oct 2026. © European Union, reused under Commission Decision 2011/833/EU.