Formula 1 Battery Rules

A look at the Formula 1 battery rules from 2014 to 2026 is interesting as this is the pinnacle of automotive racing.

Having made their debut in 2014, F1’s first genuine generation of hybrid power units took the sport to new levels.

Formula1.com

2014–2015 Regulations

• Location: The battery, officially referred to as the Energy Store (ES), was mandated to be safely located within the survival cell, specifically positioned behind the driver’s seat and beneath the fuel tank.
• Weight & Dimensions: The battery cell block and its associated packaging were required to meet a minimum weight of 20 kg and a maximum of 25 kg.
• Energy Capacity: The usable energy capacity was strictly limited to a 4 MJ difference between the maximum and minimum state of charge (SoC) while the car was on the track.
• Voltage: The ES was restricted to a maximum voltage of 1,000 V.

With a usable capacity of < 1.11 kWh

2018 Regulations

• Weight & Dimensions: The rules were updated to stipulate that the Energy Store must have a minimum volume of 22 L and a minimum weight of 30.6 kg.

2022 Regulations

• Weight: Accommodating an overall increase in the total power unit minimum weight, the minimum weight for the battery was slightly increased to 31.0 kg.

2026 Regulations

• System Overhaul: The Motor Generator Unit-Heat (MGU-H) is removed, shifting the entirety of the electrical energy recovery to the Motor Generator Unit-Kinetic (MGU-K) during braking.
• Output & Harvesting: The MGU-K’s maximum power output is nearly tripled from 120 kW to 350 kW. The maximum energy that can be regenerated and charged into the Energy Store per lap is drastically increased to between 8.5 MJ and 9 MJ.
• Weight & Voltage: The battery must meet a new minimum weight of 35 kg, while maintaining a maximum voltage of 1,000V DC.
• Cell Specifications: Teams must use lithium-ion cells, formatted as either cylindrical or pouch cells.
• Cooling & Management: Liquid cooling is mandatory. The battery must also be equipped with a Battery Management System (BMS) designed to monitor voltage, temperature, and current, and it must automatically trigger power reduction or shut down the system entirely if it detects unsafe operating conditions.
• Safety Standards: All Energy Store systems must pass UN38.3 transportation certification testing, which simulates shock, vibration, and environmental conditions to prevent chemical runaway.

Let’s put some numbers around this battery pack:

• Regen energy per lap ≤ 9 MJ = 2.5 kWh
• But total energy between SOC limits ≤ 4 MJ = 1.11 kWh
  • Usable energy ≤ 1.11kWh
  • Hence Usable SOC Window will be reduced and likely to be in the range ~30% to 70%
  • Pack total energy ~1.6 kWh to 3.7kWh
  • Discharge c-rate ~95 to 220
  • Pack gravimetric energy density 45 ~ to 106 Wh/kg
• Pack capacity ~1.88Ah to 4.35Ah

Of course, this assumes two and a bit battery full cycles per lap.

• discharge power 350 kW
  • Pack gravimetric power density ~ 10,000 W/kg
• Maximum voltage 1000V DC will be at charge voltage and hence maximum ~4.2V
  • Number of cells in series ≤ 238
  • Nominal voltage ~850V

It is interesting to look at the regulations, some images of the packs and what the regulations mean in terms of pack specifications. There is a lot of space here to operate and to design an optimum pack. There are also some interesting trades around operating voltage, SOC window, pack mass and thermal requirements.

Craig Scarborough gives an overview of the regulation changes, what that means in the lap performance and the packaging constraints [5].

On the mechanical and packaging side, the hybrid system has some key changes to accompany the power and energy changes.

As before the Battery (ES) and Control [power] electronics (CE) must sit within the survival cell structure, so now too must the MGU-K. The aim here is to keep any high voltage electrical sources away from Marshalls and fans in the case of a major accident.

Remembering that if the engine were still running, the MGU-K cabling could still be live. The electric unit can either be attached to the front of the engine but sitting inside the survival cell. Or, built into the same assembly as the Battery/electronics and connecting to the Engine via shaft.

As the MGU-K is larger, the unit and its cabling must be a minimum of 16kg, up from 7kg, while the geared connection to the engine is separately allocated 4kg. An interesting side note is the MGU-K is now rated at a similar performance to Formula-e.

Likewise the battery must be larger and is also subject to minimum weight requirements. This is to prevent manufacturers over focussing on development to reduce weights, even though they are limited with budgets in a similar manner to the teams have budget caps.

All these electrical units require cooling – the battery with dielectric fluid (oil) and control electronics and MGU commonly with water-based coolant.

Craig Scarborough, Motorsport Technology [5]

References

1. 2026 REGULATIONS EXPLAINED: All you need to know about F1’s new power units, Formula1.com
2. Evolution of the ESS Battery Unit and Control Technologies – 2015 to 2022, Honda
3. FIA 2026 F1 Regulations, FiA
4. F1’s New Era: Everything you need to know about how the FIA is making Formula 1 more competitive, more sustainable and safer in 2026, FiA
5. 2026 F1 Tech Regulations in focus – the Power Unit: 50+50=1000, Motorsport Technology
6. Audi Revolut F1 Team ignites 2026 campaign with successful first fire-up, Audi
7. Why Are 2026 Formula 1 Engines Going To Lose So Much Power?, Engineering Explained, YouTube

See also

Racing Battery Packs