Posted September 6, 20214 yr QUESTION: When an "Alternator Manufacturer" gives you an "Output at Idle" number - What do you want to hear? Most people just want to hear a high number and they're happy from that point on out.... Until they have 12.4 volts at a stoplight and 14.8 when they drive... Do you think they have been “deceived” lied to? The industry standard for an "Idle output" test is 2400 ROTOR rpm. That's approximately 800 engine rpm if you have a 3:1 pulley ratio. It’s been that way for years...& as far as today that number should really be 2000 Rotor RPM instead of 2400 because crank pulleys have got way smaller on most vehicles which makes the "Output at idle" rating even LESS. Personally, I do not feel that any passenger car alternator on the planet will do 220 amps at 2000 rotor rpm. To my knowledge there is not a single manufacturer that rates their alternators by this method. They all use the "Boss Audio Amplifier" rating method. (1000-watt amplifier rated at "4000 Watts".) Do you want to be deceived and be told what the "best case scenario" is? Such as "XX amperage" alternator will do "230+ amps at idle" On "XX car"... which idles at 1000 rpm and has an 8" crank pulley which is typically a 4:1 ratio... ANY THOUGHTS?...
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