Fuel Economy, Hypermiling, EcoModding News and Forum - EcoModder.com - View Single Post - Alternator delete

sser2 · 02-03-2018, 11:57 PM

I am working on a project to eliminate belt-driven accessories in Geo Metro to further improve fuel efficiency. The car has a 60 A alternator. Alternator voltage output is 14 V. With all accessories on, electricity consumption may be as high as 40-50 A, or close to rated output. Electric power output could be 1.1 hp, and with 60% energy losses typical for a smaller alternator, power taken from engine for electricity generation is almost 3 hp.

With Metro's engine rated power of 56 hp, one might think 3 hp is no big deal. But 56 hp is rated power at 6,000 rpm. In everyday driving, real engine speeds are around 2,500 rpm, with maximum power output at this speed of only 27 hp. This means that alternator may rob 10% of engine power when climbing a hill at full throttle. At sustained economical highway speed of 55 - 60 mph, engine power may be as little as 6-8 hp. Under these conditions, the alternator may consume as much as 1/3 of engine's power output.

Seems like not only a huge fuel savings potential, but some improvement of dynamics of this generally anemic car.

02-03-2018, 11:57 PM	#1 (permalink)
sser2 EcoModding Lurker Join Date: Feb 2018 Location: Los Angeles, California, USA Posts: 20 Thanks: 1 Thanked 3 Times in 2 Posts	Alternator delete - a huge fuel saving potential? I am working on a project to eliminate belt-driven accessories in Geo Metro to further improve fuel efficiency. The car has a 60 A alternator. Alternator voltage output is 14 V. With all accessories on, electricity consumption may be as high as 40-50 A, or close to rated output. Electric power output could be 1.1 hp, and with 60% energy losses typical for a smaller alternator, power taken from engine for electricity generation is almost 3 hp. With Metro's engine rated power of 56 hp, one might think 3 hp is no big deal. But 56 hp is rated power at 6,000 rpm. In everyday driving, real engine speeds are around 2,500 rpm, with maximum power output at this speed of only 27 hp. This means that alternator may rob 10% of engine power when climbing a hill at full throttle. At sustained economical highway speed of 55 - 60 mph, engine power may be as little as 6-8 hp. Under these conditions, the alternator may consume as much as 1/3 of engine's power output. Seems like not only a huge fuel savings potential, but some improvement of dynamics of this generally anemic car.