Fuel Economy, Hypermiling, EcoModding News and Forum - EcoModder.com - View Single Post - How much power does it take to turn an alternator

oil pan 4 · 02-05-2017, 08:30 PM

I finely got to building my test stand and putting an alternator on it.
The alternator is a modern 150 amp output ACdelco DR44G, also the AD244 is almost the same. So it's not a small alternator.
Turning the alternator at an unrealistically slow speed of about 3,600rpm only took between 100 and 120 watts for the alternator plus belt..
A little less than what I expected.
Next I had a 4 inch pulley to put on the motor. The larger pulley should spin it up to 5,760rpm.
A bit more plausible for a usable speed but no where near cruise RPM. It only used between 120 and 140 watts to turn the alternator plus belt.
A minimum cruise speed is going to be at least 7,500rpm.
Edit: no field current. Just free spinning.

02-05-2017, 08:30 PM	#14 (permalink)
oil pan 4 Corporate imperialist Join Date: Jul 2011 Location: NewMexico (USA) Posts: 11,266 Sub - '84 Chevy Diesel Suburban C10 SUV 90 day: 19.5 mpg (US) camaro - '85 Chevy Camaro Z28 Riot - '03 Kia Rio POS Team Hyundai 90 day: 30.21 mpg (US) Bug - '01 VW Beetle GLSturbo 90 day: 26.43 mpg (US) Sub2500 - '86 GMC Suburban C2500 90 day: 11.95 mpg (US) Snow flake - '11 Nissan Leaf SL SUV 90 day: 141.63 mpg (US) Thanks: 273 Thanked 3,569 Times in 2,833 Posts	I finely got to building my test stand and putting an alternator on it. The alternator is a modern 150 amp output ACdelco DR44G, also the AD244 is almost the same. So it's not a small alternator. Turning the alternator at an unrealistically slow speed of about 3,600rpm only took between 100 and 120 watts for the alternator plus belt.. A little less than what I expected. Next I had a 4 inch pulley to put on the motor. The larger pulley should spin it up to 5,760rpm. A bit more plausible for a usable speed but no where near cruise RPM. It only used between 120 and 140 watts to turn the alternator plus belt. A minimum cruise speed is going to be at least 7,500rpm. Edit: no field current. Just free spinning. __________________ 1984 chevy suburban, custom made 6.5L diesel turbocharged with a Garrett T76 and Holset HE351VE, 22:1 compression 13psi of intercooled boost. 1989 firebird mostly stock. Aside from the 6-speed manual trans, corvette gen 5 front brakes, 1LE drive shaft, 4th Gen disc brake fbody rear end. 2011 leaf SL, white, portable 240v CHAdeMO, trailer hitch, new batt as of 2014. Last edited by oil pan 4; 02-05-2017 at 09:18 PM..