Bad Alternator??

[Ibach73dart]

I got a new battery today and my question is if I have a bad alternator or not. I bought the alternator less than a year ago. I hook up the new battery and I tested the voltage and is around 16.35 with engine running, 16.50 with headlights on and charging system over 16.00. Are those too high? My engine is a 318.
Thanks
Bach

 

[Abodybomber]

I would try a new voltage regulator,to start. That kind of voltage ,usually kills batteries,anyways . Diagnosis ,after that.

 

[Ibach73dart]

I would try a new voltage regulator,to start. That kind of voltage ,usually kills batteries,anyways . Diagnosis ,after that.

Sorry I forgot to mention that before I git the new battery the voltage failed when they test my charging. I bought a new regulator also. I'm just worrying about 16 output number. Is it normal 13-14?

 

[67Dart273]

1.........Make absolutely certain you have "a" correct alternator and that the field is not shorted. You should have TWO field connectors, and a blue and green wire hooked to those connectors

2..........Determine if the regulator has control of the alternator. To do that, unhook the green field wire, but leave the blue one connected. Run the engine, and run the RPM up and down a bit. Voltage should be below 13V

Your alternator should look something like this:

This is an older design, but it is till made in 70 or later, and has TWO field terminals

The one on the left, below, is a later 70's so called "squareback" and is a better design. The one on the right, below is NOT what you want. It only has ONE field terminal, the other being grounded.

 

[67Dart273]

If your system passes the above quick checks, then it is likely something-------------


1....Could be a bad battery but not likely. "New" does NOT mean "good."

2.....Most likely it is VOLTAGE DROP in the ignition harness

3.....Also likely is poor grounding between regulator case and the battery

4.....In rare cases could be a bad regulator

TO CHECK voltage drop, do the following:

GROUND...........Run the engine at "fast idle," and make the following check first with all accessories off, then again with heavy loads, heater, lights, etc, turned on. Switch your meter to "low" DC volts. stab one probe into the top of the NEG battery post

Stab the remaining probe into the regulator mounting flange. You need to stab through any chrome, paint, or rust. What you are hoping for is a VERY low reading, the lower the better, and zero is perfect. More than .2V (two tenths of one volt) is too much and means you have a bad ground

VOLTAGE DROP. The regulator power source is also the voltage sensing terminal. This comes from the battery, through the bulkhead connector, ammeter, ignition switch, back out the bulkhead terminal through the harness, and to the VR. ANY voltage drop in this harness can cause OVER charging.

To check, Hook your meter to "switched ignition." This can be the 'high' side of the ballast resistor, or the blue field wire on the alternator. Turn the key to 'run' but with engine stopped. Again, with your meter on "low" DC volts, stab your remaining probe onto the POS battery post

As in the previous test, you are hoping for a low reading, the lower the better. More than .3V (three tenths of one volt) means you have a bad connection somewhere in that path.

 

[Ibach73dart]

1.........Make absolutely certain you have "a" correct alternator and that the field is not shorted. You should have TWO field connectors, and a blue and green wire hooked to those connectors

2..........Determine if the regulator has control of the alternator. To do that, unhook the green field wire, but leave the blue one connected. Run the engine, and run the RPM up and down a bit. Voltage should be below 13V

Your alternator should look something like this:

This is an older design, but it is till made in 70 or later, and has TWO field terminals

The one on the left, below, is a later 70's so called "squareback" and is a better design. The one on the right, below is NOT what you want. It only has ONE field terminal, the other being grounded.

Thanks, the previous owner changed out the original alternator n changed the wire to internal. The alternator is different from your pictures. Here is the back of my alternator n I will get the front later.

 

[moparlover]

well you found the problem. usually the older ones work fine, especially if your wiring is well maintained.

if switching to the newer denso types, you should have a sense wire that senses the voltage at a remote spot (usually you hook the sense wire near the starter solenoid, or battery or headlight relay area, not at the alternator itself)... this allows the alternator to adjust the voltage to meet the demand at the remote spot. (has a volage regulator built in)

with the older types of altenators, if your voltage regulator is good, then you will be all set.

however with your setup, the voltage regulator is not regulating anything and the alternator is pumping full out

 

[67Dart273]

Is this an imported car, IE from Mexico or S America?

 

[Ibach73dart]

well you found the problem. usually the older ones work fine, especially if your wiring is well maintained.

if switching to the newer denso types, you should have a sense wire that senses the voltage at a remote spot (usually you hook the sense wire near the starter solenoid, or battery or headlight relay area, not at the alternator itself)... this allows the alternator to adjust the voltage to meet the demand at the remote spot. (has a volage regulator built
in)

with the older types of altenators, if your voltage regulator is good, then you will be all set.

however with your setup, the voltage regulator is not regulating anything and the alternator is pumping full out

The previous owner had audio systems on there that's why he went with a bigger alternator. He ran the positive from the alternator to the battery also the ground. Can I converted back to the original alternator? I'm gonna take it to an auto electric and see if they can diagnosis.

 

[Ibach73dart]

Is this an imported car, IE from Mexico or S America?

Nope, it's from here.

 

[BillGrissom]

Next time, please give us the photo in post #6 at the outset. You also didn't tell us anything about your car, like the year & engine (~1970 in photo?). Is your photo upside down or is the alternator on the driver's side of a slant six engine? If so, it could be a truck setup, but looks more cobbled than that.

Yes, you can switch to a factory Mopar alternator. You can buy aftermarket brackets easy for a small block or big block engine. For a slant, junkyard or ebay. I would get the later "square-back" alternator (bottom left photo of post #4) and a later Vreg (triangle plug). You can mount the Vreg near the alternator, like I did in my 65 Dart, for simpler wiring. Ground the body of Vreg with a dedicated wire, unless you like to rely on rusty sheet metal screws and getting stranded on the road as a result.

 

[Ibach73dart]

Next time, please give us the photo in post #6 at the outset. You also didn't tell us anything about your car, like the year & engine (~1970 in photo?). Is your photo upside down or is the alternator on the driver's side of a slant six engine? If so, it could be a truck setup, but looks more cobbled than that.

Yes, you can switch to a factory Mopar alternator. You can buy aftermarket brackets easy for a small block or big block engine. For a slant, junkyard or ebay. I would get the later "square-back" alternator (bottom left photo of post #4) and a later Vreg (triangle plug). You can mount the Vreg near the alternator, like I did in my 65 Dart, for simpler wiring. Ground the body of Vreg with a dedicated wire, unless you like to rely on rusty sheet metal screws and getting stranded on the road as a result.

Sorry Bill, mine is a 73 dodge dart swinger with 318 4b set up. Its on the passenger side. I took the picture from behind to show the wires. i will take more pic after work. Below is my engine, forgot I had it on my phone.

 

[67Dart273]

The thing is...........he no longer has a "Mopar style" bracket setup

 

[Ibach73dart]

The thing is...........he no longer has a "Mopar style" bracket setup

I know and the belt is slightly off a little bit! And when I removed the bracket to painted, one said "ford" on it! I need a mopar style setup.

 

[nm9stheham]

Sure you can convert back to the original syle alternator....you can put in all sorts fo alternators. The quesiton is what wiring is left in there that will support the Chrysler type alternator and external regulator. You need to start with an appropriate schematic, and then see what is in your car. I would sugget you work here and not just take it to an 'auto electric' shop; it is hard to say what they will do to your car's wiring if you do not know what needs to be done yourself and have enough understanding to direct it.