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Batteries not the only route to EV efficiency

  • Magazine Article
  • 21TOFHP06_02
Published June 01, 2021 by SAE International in United States
  • English

Allison CTO stresses efficiency and safety of propulsion units also are critical to reducing cost, improving performance and ultimately winning over customers.

Much of the talk around the switchover to electric power in commercial electric vehicles (EV) focuses on batteries, whether it be their range, weight, energy and power density, or expected life. Allison Transmission supplies hybrid propulsion products for transit buses and is bringing to market e-axles for battery-electric vehicles (BEV). For each of those applications, a different battery chemistry will win out as OEMs and operators factor the cost, performance, duty cycle and lifespan of the batteries into the vehicle's total cost of ownership (TCO).

Battery cost is falling but remains a high-value proportion of the TCO. For BEV applications, which might only require one daily discharge cycle and an overnight charge, nickel-manganese-cobalt (NMC) batteries seem to offer the best balance today. Other chemistries have a higher cycle life and power capability, but also come at a significantly higher cost. For hybrids, lithium-titanate-oxide (LTO) and other chemistries have much higher specific power and lifespan. With the constant movement of energy level in a hybrid battery, a higher cycle capability is required.