DartThis74
Well-Known Member
I was driving my ‘74 dart yesterday and realized the needle isn’t reading in the middle. What is this needle position on the gauge telling me? What are the other marks supposed to mean as well?
How to do you read the alternator gauge?
- Thread starter DartThis74
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The Way your gage reads, it is over charging.
How long was it running when you took the pic. Should go to center after 5 or so min's, on good battery.
Or you might have high resistance some where in the circuit.
It could be lots of common things, in the wiring, specially in the bulk head connections.
Is the batt good, how old is it. ??
Check all your connections, use dielectric grease on batt connections
Dave
How long was it running when you took the pic. Should go to center after 5 or so min's, on good battery.
Or you might have high resistance some where in the circuit.
It could be lots of common things, in the wiring, specially in the bulk head connections.
Is the batt good, how old is it. ??
Check all your connections, use dielectric grease on batt connections
Dave
DartThis74
Well-Known Member
Currently... I pretty much have been driving the car about 1-2 times a month on a weekend. When I first start the car it sits in the middle roughly but if I push the gas it bounces all the way to the right until I let of the accelerator. After 15 minutes maybe it will finally settled and stay fixed. Battery is a few years old, but doesn't have dielectric grease on it though.
If it is truly overcharging that would just make the battery wear out faster I assume?
Demonic
Well-Known Member
Sounds as though it is just recharging from the drain of the initial start cranking. For a seldom driven car such as yours, that's not unusual. To really know the state of the battery, you'd need a hydrometer if you can check the specific gravity of the cells, that is, not a sealed battery.
The 'alternator' gage is an ammeter showing current to or from the battery.
Normally it sits at zero after the battery has recharged.
Possible reasons for this include
1. Voltage regulator not working.
2. Battery low combined with alternator that's producing at reduced capability. An alternator producing normally should be charging the battery at fast idle.
If the regulator isn't working, then the whole system is running at higher than 15 Volts whenever the engine rpms are increased. Every electric device given power at higher voltage will suck more current, so lots of things can get damaged.
In my opinion, the first check would be to take a handhand multimeter and measure voltage at the battery, engine running at idle rpm (650?) and then at 1250 rpm, or fast idle (1600ish). If it goes up a little, but stays under 15 V, increase rpms more just be sure.
If that checks out ok, then check voltage at idle and 1250 or 1600 at the at the alternator output (if accessible - some are covered in a boot), and at the nearest junction to the voltage regulator sense wire (back probe at ballast resistor or the blue wire conencted to the alternator).
Normally it sits at zero after the battery has recharged.
That means charging is increasing with rpm.
Possible reasons for this include
1. Voltage regulator not working.
2. Battery low combined with alternator that's producing at reduced capability. An alternator producing normally should be charging the battery at fast idle.
Sounds like the battery could use a good charge on a charger.
it will cook off the water (acid), or occassionally worse.
If the regulator isn't working, then the whole system is running at higher than 15 Volts whenever the engine rpms are increased. Every electric device given power at higher voltage will suck more current, so lots of things can get damaged.
In my opinion, the first check would be to take a handhand multimeter and measure voltage at the battery, engine running at idle rpm (650?) and then at 1250 rpm, or fast idle (1600ish). If it goes up a little, but stays under 15 V, increase rpms more just be sure.
If that checks out ok, then check voltage at idle and 1250 or 1600 at the at the alternator output (if accessible - some are covered in a boot), and at the nearest junction to the voltage regulator sense wire (back probe at ballast resistor or the blue wire conencted to the alternator).
Yes. That or load tester.
If you drive your car occasionally and a few weeks between drives, put a trickle charger on it one day a week or buy a battery maintainer. It looks like it's charging about 20 amps. Pretty normal for a battery that is low on charge. Yes you could test it or have it tested but it needs to be fully charged to get an accurate test.
I read mine with my eyes, generally.
67Dart273
Well-Known Member
The VERY FIRST thing you need to do is get the car running and clip a voltmeter direct to the battery. Increase RPM to simulate cruising speed and see what the meter reads. If it's very much above 14, or an absolute limit of "above 15.5" (and that is somewhat high) then the regulator is not properly controlling the voltage.
If the voltage is 14 or lower the battery is "down" (somewhat discharged) or bad. IE defective battery.
If the voltage is 14 or lower the battery is "down" (somewhat discharged) or bad. IE defective battery.
DartThis74
Well-Known Member
I can certainly look into doing this!
DartThis74
Well-Known Member
Great diagram! I'll take some time to look into this as well! Thank you
I drained my battery, 3 years old, till it would not start the car. Jumpered and all was fine but ammeter was in the same position. I drove it for 45 minutes and it was still there.
Had battery tested came back good but low on charge put it on barttery charger all night. Next day charge indicator in the center to just right of center.
Shocked me
Had battery tested came back good but low on charge put it on barttery charger all night. Next day charge indicator in the center to just right of center.
Shocked me
You're lucky. Full charging like that can trash a amp meter and Then no chargo' in battery-o.
Mopar charging systems aren't designed for and don't like full alternator output.
It was not full it was 1/2 way between center and 40, still made me nervous
The systems are design to maintain battery state of charge and provide current for accessories and the old systems do that poorly.
No alternator likes being maxed out for long periods of time.
Charging Battery with Alternator - Warning
Heck most electric equipment has far less than 100% duty cycles.
The weakest connection on the OP's '74 is probably the alternator output terminal connection at the bulkhead.
It's has the terminals with the least surface area in the circuit, minimal airflow for cooling, and all of the current is passing through it. At the mainsplice the current divides so everything downstream of that sees less current through it.
My biggest concern, and I guess 67dart273's too, is that the VR is not regulating.
Does he have a bunch of thing pulling power at the battery????
That would show an overcharge condition when in fact it was just providing energy to those accessories.
That would show an overcharge condition when in fact it was just providing energy to those accessories.
As suggested, if you don't drive the car regularly you should buy a maintainer. I have one hooked to my Ram truck because it doesn't see regular use & it fires up first time now.
67Dart273
Well-Known Member
Very good point If you add power drawing accessories to a system on the "wrong side" of the ammeter ("alternator gauge") it causes the thing to read incorrectly.
When something like factory headlights are wired in, without the engine running, the headlights show a draw on the meter, "neg" or left of center. When the alternator brings that back to zero, or center, the alternator is making up for the headlights, and no additional charge is going to the battery. When the meter goes right of zero, there is charge going to the battery. You, the driver don't know if this is because the battery is low, or if the thing is overcharging.
But when you add something like fans, stereo, pumps and power it off the battery direct, or the starter relay stud, this puts the accessory on the WRONG SIDE of the ammeter, and when you power up the load, the meter will not show discharge (not running) but when running, the meter will always show a charge which is the current the alternator puts through the ammeter to run the accessory
On ANY ammeter hookup, (not counting the starter) all accessories and loads are on the same side of the ammeter as the alternator/ generator. ONLY the battery is on the opposite side
And taxing the bulkhead and ammeter along the way
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