Electric Starting of Large Aircraft Engines

This paper examines why large aircraft engines are started the way they are today, and why that may all change in the not too distant future.

Electric starting of aircraft engines and Auxiliary Power Units (APU) has been limited to 28 VDC battery systems, with starting power typically under 10 kW. Above this power level the very high battery currents, and resulting voltage drops, make the approach less and less practical.

Large engines for commercial transports may require more than 100 kW to start so low voltage battery starting will not be an option.