One wire alternators
Burning Brakes
Joined: Feb 2006
Posts: 1,024
Likes: 1
From: AL
toddalin, i'm not sure exactly of all the mods to your car, but you're mostly correct in that the factory ammeter (shunt type) uses a voltage differential between two connection points in the harness to convert to a display in amps. most vettes have one near the sensor connection, or horn relay, and one near the starter. This is the wire used to charge the battery. Your modifications evidently didn't affect this, so your ammeter still senses a current through this wire. in the factory charging configuration, only current flowing to/from the battery is seen by the ammeter. if you have run a (bypass? not sure from post) wire from the alternator to the battery, then the ammeter is no longer seeing the charging current.
everything else being equal, a higher output alternator would charge at a greater rate at first, then drop down to values you'd normally have seen. More info would be needed to interpret the meaning of the values your ammeter is now displaying. Hope this helps . . .
everything else being equal, a higher output alternator would charge at a greater rate at first, then drop down to values you'd normally have seen. More info would be needed to interpret the meaning of the values your ammeter is now displaying. Hope this helps . . .
Le Mans Master
Joined: Oct 2000
Posts: 8,897
Likes: 1,357
From: Santa Ana CA
toddalin, i'm not sure exactly of all the mods to your car, but you're mostly correct in that the factory ammeter (shunt type) uses a voltage differential between two connection points in the harness to convert to a display in amps. most vettes have one near the sensor connection, or horn relay, and one near the starter. This is the wire used to charge the battery. Your modifications evidently didn't affect this, so your ammeter still senses a current through this wire. in the factory charging configuration, only current flowing to/from the battery is seen by the ammeter. if you have run a (bypass? not sure from post) wire from the alternator to the battery, then the ammeter is no longer seeing the charging current.
everything else being equal, a higher output alternator would charge at a greater rate at first, then drop down to values you'd normally have seen. More info would be needed to interpret the meaning of the values your ammeter is now displaying. Hope this helps . . .
everything else being equal, a higher output alternator would charge at a greater rate at first, then drop down to values you'd normally have seen. More info would be needed to interpret the meaning of the values your ammeter is now displaying. Hope this helps . . .
C6 the C5 of tomorrow
Joined: Nov 2000
Posts: 6,665
Likes: 2
From: Twin Cities Minnesota
Maybe it doesn't swing quite as far because the new 100-amp alternator does a better job of keeping the battery charged than the old 42-amp unit through the external regulator did, and it charges faster so the gauge swing to the right doesn't last as long.
Because the battery is kept at a higher state of charge, it needs less charging and the amp gauge simply reflects this.
Because the battery is kept at a higher state of charge, it needs less charging and the amp gauge simply reflects this.
If anything the amp gauge is showing less current because the meter is no longer showing you relevent information.
If your therory was correct it would show more current not less current since the alt would be putting out more power.
You see the amp gauge should be at zero unless something is drawing power, like lights, starter etc.
Le Mans Master
Joined: Oct 2000
Posts: 8,897
Likes: 1,357
From: Santa Ana CA
Wrong
If anything the amp gauge is showing less current because the meter is no longer showing you relevent information.
If your therory was correct it would show more current not less current since the alt would be putting out more power.
You see the amp gauge should be at zero unless something is drawing power, like lights, starter etc.
If anything the amp gauge is showing less current because the meter is no longer showing you relevent information.
If your therory was correct it would show more current not less current since the alt would be putting out more power.
You see the amp gauge should be at zero unless something is drawing power, like lights, starter etc.
Sorry, the meter shows the differential between the voltage at the starter and the horn relay regardless of what type alternator is installed. If the gauge isn't swinging as far, its because the differential between these two points has been lessened.
Lots of things can actually account for this, including the way that the internal voltage regulator processes information differently than the external regulator. Perhaps with the old alternator/regulator, the on/off cycles would be further between (wider voltage swing) allowing more battery drain before going into charge mode. That is just one possible scenario.
