Alternator Amp Size?
I don't trust any aftermarket alternator, except maybe those listed for aircraft.
If you know someone with a carbon pile and ammeter, or combo unit like an VAT 40, you can test them on the car. I picked up VAT 40 this fall. Maybe next week I'll see what the square back currently on my car does.
As far as I can tell, there is no standard for alternator 'ratings.'
The service manual tests are to be done at 1250 rpm, at 15 Volts. This is actually a pretty good test. 1250 is between regular idle and fast idle on a typical car. My understanding is testing the output at 15 Volts is worst case situation. At lower voltage it can put out more current. Alternator output is power. P = V x I
Those outputs are not the ratings. In the sales book, they call them 34, 37, and 50 amp alternators that year.
https://www.hamtramck-historical.co...lershipDataBook/1971/71_Valiant_Duster_20.jpg
The '73 Dodge FSM actually lists the rating with the new squarebacks.
Notice they state current at the carbon pile attached to the battery is about 5 amps less than the output of the alternator. Where did the amps go? To power the ignition and the rotor. The current divided between the regular wiring and the test wiring.
Sometimes higher rated alternators do worse at low rpm. This is from a Delco catalog for 10 SI GM replacement.
Depending on the pulley ratio, the '72 amp' alternator might be worse at idle and off idle than the '63 amp' alternator.
In reverse order.
I don't trust any aftermarket alternator, except maybe those listed for aircraft.
If you know someone with a carbon pile and ammeter, or combo unit like an VAT 40, you can test them on the car. I picked up VAT 40 this fall. Maybe next week I'll see what the square back currently on my car does.
As far as I can tell, there is no standard for alternator 'ratings.'
The service manual tests are to be done at 1250 rpm, at 15 Volts. This is actually a pretty good test. 1250 is between regular idle and fast idle on a typical car. My understanding is testing the output at 15 Volts is worst case situation. At lower voltage it can put out more current. Alternator output is power. P = V x I
Those outputs are not the ratings. In the sales book, they call them 34, 37, and 50 amp alternators that year.
https://www.hamtramck-historical.co...lershipDataBook/1971/71_Valiant_Duster_20.jpg
The '73 Dodge FSM actually lists the rating with the new squarebacks.
Notice they state current at the carbon pile attached to the battery is about 5 amps less than the output of the alternator. Where did the amps go? To power the ignition and the rotor. The current divided between the regular wiring and the test wiring.
Sometimes higher rated alternators do worse at low rpm. This is from a Delco catalog for 10 SI GM replacement.
Depending on the pulley ratio, the '72 amp' alternator might be worse at idle and off idle than the '63 amp' alternator.
