Amp output ?

[Derek]

I have a 67 SV and wonder what the amp reading should be at the ammeter in the car ? (just the car running, no fans, lights etc.) the alt. output in the WSM is 35 amps. I don't believe that all of that is going back to the battery !

Thanks for the lesson

Derek

 

[V_Mad]

The amount of current indicating on the ammeter can vary beween a couple of amps, to about 35 amps depending on the state of charge of the battery and the load. With a healthy, fully charged battery and no loads switched on it will hardly show any charge (except just after starting the engine when a small charge will show).
Do you have a problem with your car?

 

[Tom H]

What Chris wrote is correct, assuming the ammeter is wired as per the factory setup. But let me also add that if the battery is fully charged the ammeter should show near zero, even IF all the lights and accessories are turned on. The ammeter should read the amount of current going into (+)or out of (-)the battery, nothing else. If the motor is off then any current is from the battery and so if you turn on the lights, etc, the ammeter should read - . Once you start the car, the alternator should put out enough current to supply the lights and also charge the battery. So the meter reads + 25 or so indicating charge going into the battery. If you turn off the lights then, the meter may go up to 30 or 35, as all the alternator output can go into the battery, which got drained a bit powering the starter motor. As the battery gets charged, its voltage rises and the regulator senses this and reduces the current going in to the battery, and the meter declines and eventually gets near zero. Even if you turn the lights on, the meter still reads near zero, because the current for the lights comes from the alternator, not the battery.

Tom

 

[Derek]

Thanks, no I have no real issues, I just replaced the battery, the old one just would not reliabley crank the car over after I messed about with light setc. with the motor off. I have not seen the ammeter go over a couple of amps, let alone 25 + so I assume all is well. If I get the same battery / starting issues, well we'll see

Derek

 

[RootesRooter]

You're only seeing it go to "a couple of amps" - literally? Even with a new battery, I would expect to see the needle go to around 15-20 amps for a short time after cranking the starter, dropping steadily back to just above zero over a minute or two of running time.