The energy loop
Every braking zone wastes energy as heat — unless you catch it. The MGU-K (Motor Generator Unit–Kinetic) connects to the drivetrain and runs both ways: under braking it acts as a generator, converting the car's motion into electricity stored in the battery; on the straights it flips into motor mode, feeding that energy back as propulsion.
The loop runs every lap: harvest into corners, deploy out of them. Under the 2026 rules the electrical side contributes roughly half the car's total power.
Deployment strategy
The battery can't hold unlimited energy, so when to spend it is a genuine strategy. Software plans a default deployment map per lap — prioritizing the straights where speed matters most — and drivers adjust with steering-wheel switches: full attack to pass, extra harvesting to save for later.
Defending is electric too: a leading driver saving battery for the finish-line straight can neutralize an attacker's advantage. Watching the ERS chess within a battle is one of modern F1's hidden pleasures.
From KERS to today
The first system, KERS (2009), offered a modest 60 kW for 6.7 seconds per lap via a boost button. The 2014 hybrids made recovery continuous and powerful; 2026 tripled electric output again and added the manual-override attack mode. In fifteen years, electricity went from party trick to half the propulsion.