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A dumb question!

Big Al's GTX

Big Al's GTX

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The Waters Edge, Worth, Illinois.
Today I received my 69 GTX and was checking her out and my questions is is it normal for the Alternator needle to move to
the charging position when pressing the gas paddle and than returning when off the gas ?
 
It's called an ammeter. It's indicating whether the battery is being charged or discharged. It measures amperage, or flow, of electricity. In your case, the alternator is charging a discharged battery.
 
Big Al's GTX said:
Today I received my 69 GTX and was checking her out and my questions is is it normal for the Alternator needle to move to
the charging position when pressing the gas paddle and than returning when off the gas ?
Click to expand...
It is not uncommon to show little or no charging condition at idle rpms. If that were happening at higher engine speed I'd be looking for issues. You should be just fine.
 
I seem to recall original distributors didn't charge at idle - or below a certain RPM. Could be wrong.
 
LOL ! Alternators !! Got "distributor" on my mind since that's the last thing I was fussing with yesterday !!!
 
Immediately after charging or if the battery is down a little, the needle should rise into the charge zone depending on how depleted the battery is or the engine speed. As the battery is recharged it will fall back to or slightly above center. But yes, with these old alternators they are not very efficient at low idle rpm and depending on its condition it may barely do more than keep the car running at low rpm in gear with an automatic, much less charge the battery. And then as engine speed increases alternator output rises. At least that’s been my experience.
 
WileERobby said:
It's called an ammeter. It's indicating whether the battery is being charged or discharged. It measures amperage, or flow, of electricity. In your case, the alternator is charging a discharged battery.
Click to expand...
In a 69 GTX the ammeter gauge in the cluster is labeled "Alternator" so his original question is phrased correctly.
But yes the indication he describes is normal operation after starting the engine. (You just drained the battery a bit when cranking it)
After 5 - 10 minutes of normal driving it should sit pretty close to center or maybe just slightly to the "C" harge side.
 
Don Frelier said:
In a 69 GTX the ammeter gauge in the cluster is labeled "Alternator" so his original question is phrased correctly.
But yes the indication he describes is normal operation after starting the engine. (You just drained the battery a bit when cranking it)
After 5 - 10 minutes of normal driving it should sit pretty close to center or maybe just slightly to the "C" harge side.
Click to expand...
He also refers to the car as "her", are these cars female ? :poke: :lol:
 
Don Frelier said:
They can be tempermental, so then YES.
Click to expand...
1719411628363.png
 
A significant, or prolonged, ammeter charging indication with a healthy fully charged battery would be abnormal at any engine rpm with this charging system. As mentioned, running an original spec’d alternator, some discharging at engine idle speeds would be somewhat normal. The current flow of mis-placed added loads at the battery or battery side of the ammeter will register as false charging as well. A centered or slight charge indication above idle would indicate normal healthy charging system status.
 
These 50-60 year old electrical systems aren't as efficient as modern cars. Plus your idle speed might be slightly lower than manufacturer specs depending on modifications.

At idle mine is ho-hum, but even an extra 100 or 200 rpm will send it into charge. So 700 rpm = no charge, but 800 or 900 rpm = charging.

Put the lights on at idle and it will probably drop a bit more. A modern car can sit there all day at idle with lights, radio, wipers, aircon going and still be charging the battery.
 
Further to the above, assuming they were like this when new (and I don't know as I wasn't around), I've often wondered why they didn't put a slightly smaller pulley on the alternator so it made charge at very low rpm? Because it would spin too fast and throw belts at high rpm?
Any ideas?
 
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