Amp gauge shunt
However skykeith is correct that the connecting plate in these ammeters (A-body 'til '75) work differently than a remote shunt.
Recently someone on the IFSJA forum found a fairly reasonably priced remote shunted ammeter. In case anyone is interested, this is an option to the aircraft and marine ones.
https://www.westach.com/product-page/2c6-3
Although the 100 amp shunt isn't cheap. https://www.westach.com/product-page/237-100
A. In general, they didn't. Looking through the sales books, pretty much only find '60 amp' rated alternators as an option for fleet buyers, until maybe '73.
For example even the C-bodies, '46 amp' was the highest rated alternator in '68
The 1970 Hamtramck Registry - 1968 Dodge Dealership Data Book - Introduction
The 1970 Hamtramck Registry - 1968 Canadian Fleet Buyers' Informational Manual - Dart
Somewhere around '73 some non-fleet cars got an optional '60 amp' Chrysler alternators when equiped with electric window defrost grids. Those had the main power feeds wired through a grommet.
B. The rating is higher than the expected normal load. Running an alternator at its maximum output for long periods of time (100% duty cycle) can burn things out.
Keep in mind that all alternators produce less power at lower rpm.
Alternator maximum output vs rpm always looks something like this.
This is why the crank to alternator pulley ratio is so important for low rpm performance.
C. Chrysler probably didn't expect or want the battery to be charged at 40 amps or even 30 amps. That could can cook a battery or worse.
One reason for using higher output alternator was to power additional equipment, especially at when idling. So in those cases the extra power being demanded wasn't going through the ammeter. However I recall seeing some reference to a modified or different ammeter that went with a fleet wiring setup. I don't remember where now - maybe in a parts book. We can see from the '68 fleet book that a larger battery was required with the 60 and 65 amp alternators. Probably the reasons for the larger battery were so they wouldn't demand as much recharge and also not get cooked as quickly by high recharge rates. Just guessing on that.
@bbab3 wanted to use an ammeter with a beefed up shunt. One option was to do it like he did his powerwagon, and the other was to make a remote shunt. 67dart273 was answering the question of how to check the effect on calibration.
However skykeith is correct that the connecting plate in these ammeters (A-body 'til '75) work differently than a remote shunt.
Recently someone on the IFSJA forum found a fairly reasonably priced remote shunted ammeter. In case anyone is interested, this is an option to the aircraft and marine ones.
https://www.westach.com/product-page/2c6-3
Although the 100 amp shunt isn't cheap. https://www.westach.com/product-page/237-100
This I can answer now. It was a bit off topic and I assumed a rhetorical question, but seems like since the thread has been revived its worth addressing.
A. In general, they didn't. Looking through the sales books, pretty much only find '60 amp' rated alternators as an option for fleet buyers, until maybe '73.
For example even the C-bodies, '46 amp' was the highest rated alternator in '68
The 1970 Hamtramck Registry - 1968 Dodge Dealership Data Book - Introduction
The 1970 Hamtramck Registry - 1968 Canadian Fleet Buyers' Informational Manual - Dart
Somewhere around '73 some non-fleet cars got an optional '60 amp' Chrysler alternators when equiped with electric window defrost grids. Those had the main power feeds wired through a grommet.
B. The rating is higher than the expected normal load. Running an alternator at its maximum output for long periods of time (100% duty cycle) can burn things out.
Keep in mind that all alternators produce less power at lower rpm.
Alternator maximum output vs rpm always looks something like this.
This is why the crank to alternator pulley ratio is so important for low rpm performance.
C. Chrysler probably didn't expect or want the battery to be charged at 40 amps or even 30 amps. That could can cook a battery or worse.
One reason for using higher output alternator was to power additional equipment, especially at when idling. So in those cases the extra power being demanded wasn't going through the ammeter. However I recall seeing some reference to a modified or different ammeter that went with a fleet wiring setup. I don't remember where now - maybe in a parts book. We can see from the '68 fleet book that a larger battery was required with the 60 and 65 amp alternators. Probably the reasons for the larger battery were so they wouldn't demand as much recharge and also not get cooked as quickly by high recharge rates. Just guessing on that.
