2022 BTCC Hybrid Battery

The 2022 BTCC hybrid battery as designed and manufactured by Delta-Cosworth. This is an extreme version of a Mild Hybrid Electric Vehicle (MHEV), thus has a small energy storage capacity that is designed to fill in the engine power.

The 48V battery pack is our advanced energy store for the hybrid system. It includes a 12V charging connection and BMS (Battery Management System). The package is self-isolating on disconnection from the car and when the vehicle charger is disconnected.

The Delta Cosworth BMS monitors battery cell health and the energy control for deployment and regeneration. It also has the responsibility for sending and receiving of all battery related data. Lastly, it manages the control strategies sent from the Antares 8 VCU, these strategies are calculated as a result of the data received from the BMS itself.

BTCC Hybrid System, Cosworth

Specifications

  • Energy = 1.5 kWh (1.7 kWh total)
    • SoC Window = 88%
  • Nominal Voltage = 51 V
    • Voltage Range = 57V to 43V
    • Additional regulated 13.8V output at up to 92A
  • Nominal Capacity ~ 33.3 Ah
  • Configuration = 14s1p

The nominal capacity was estimated based on nominal voltage and total capacity. This is a high power cell easily capable of a 20C discharge for 15s.

  • Power = 30 kW15s
    • Maximum current = 650A for “bump starts”
    • On track maximum current = 450A
  • Pack Mass = 20 kg

Cooling

  • Liquid cooled cells
    • Micro-bore cooling plates located between the cells [4]

The cooling plates for the cells are also used to cool the DC-DC that supplies the 12V for the car from the same pack.

Electronics

The battery pack also contains the DC-DC to supply the 12V system for the race car.

  • 4x Vicor DCM3623 isolated, regulated DC-DC Chip Modules
  • Voltage = Regulated 13.8V
  • Maximum current = 92A
  • Maximum power = 1270W

Durability

Estimation is that the battery will operate for 3 seasons before they will see a drop in cell performance.

  • 16 to 25 laps per race
  • ~30 minutes per race
  • 2x 40 minute practices + 1x 30 minute qualifying per round
  • 3 races per round
  • 10 rounds per year
  • Total running time = 2000 minutes/season
  • ~110mph fastest lap time
  • ~3500 miles / season

This post has been built based on the support and sponsorship from: About:EnergyAVANT Future MobilityQuarto Technical ServicesTAE Power Solutions and The Limiting Factor. 

Packaging

The Delta Cosworth hybrid battery unit is self-contained and resides in what was the passenger seat area of the car, linked to the electric motor generator unit incorporated into the (yes, you guessed it) regulated Xtrac gearbox. The unit provides around an 8% increase over the 379+hp provided by the 2.0L combustion engine, with the amount of hybrid boost available dependant on a number of factors but ultimately balanced to ensure close racing. This extra power won’t be enough to support an outright pass, but will allow gaps to close and put pressure on drivers to defend or support an attack.

Not Your Average Hybrid: West Surrey Racing’s BTCC 330e [3]

The battery case is carbon fibre and designed to fit into the footwell of the BTCC cars, within the safety cage.

Standards

Even though this is a system that operates at less than 60V DC it had to meet the FIA Formula E 400V electrical standards.

Metrics

  • Pack Gravimetric Energy Density = 85 Wh/kg
  • Pack Gravimetric Power Density = 1500 W10s/kg

The gravimetric power versus energy comparison shows just how good this battery pack is, especially considering that this also includes a DC-DC converter.

References

  1. The World’s First Affordable Competition Hybrid System, Race Tech
  2. Welcome to the BTCC Hybrid Era, BTCC YouTube
  3. Not Your Average Hybrid: West Surrey Racing’s BTCC 330e, SpeedHunters
  4. British Racing Green, Electric & Hybrid
  5. How BTCC Completed Its First Hybrid Season, RaceCar Engineering

Battery Pack Ragone Plot

In simple terms:

  • Moving to the right on the x-axis is increasing in energy density
  • Moving up the y-axis is increasing the power density

There are a number of factors that make it difficult to engineer a pack with very high power and high energy density.

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