Hello.
I am an Electrician, However this is dc. I am losing battery voltage and the battery guage is now down to 1/4. I need to trouble shoot the Alternator or the voltage regulator. I have the single wire coming off the back of the ALT. and then the two wire plug. I am just not sure where to test from and could use some knowlege. The battery is brand new, so that is eliminated. Thank you :confused:

Do you mean the battery is going flat with everything off or not charging at all ?

Hello
The battery is going flat while driving the car. It is not charging at all.
I need to troubleshoot from the battery back to the alternator but not sure where the voltage regulator fits in or how that circuit works.

This thread should help you understand and diagnose your charging problem.
http://www.chevelles.com/forums/showthread.php?t=192111&highlight=testing+alternator

This is great stuff. I will be troubleshooting today.
I will post what I find

OK
A little confusion. Where a plug would go into a Voltage regulator, there is a 4 prong cap the connects #1 to #4 and #2 to #3. Then there is a small silver AC Delco mechanism. What would that be. There seems to be a coil plugged into it. What would energize this? Still confused:confused:

I am sorry.
If dean checks out this post again, It is a 1965 Chevrolet malibu. I am not sure about the Regulator or that Delco module. It is very old and has no number that I can see. My first step is to try and see if the Alt is puting out voltage. The 2 conductor plug is getting battery voltage to excite.

First determine if you alternator is a externally (which is original for the car) or has been converted to a internally regulated alternator. You can tell by looking at the position of the 2 small terminals. See this post, with pics http://www.chevelles.com/forums/showthread.php?t=105661

I had done a ton of research yesterday. (Sunday) It has been converted to an internal regulated Alternator. There is a jumper block in the old regulator plug. I checked all the conductors for continuity and they ring out fine. How do I do an Alt test?

Charging voltage should be 13.8-14.5 volts at the battery, (a little higher at the alt BAT stud) if you are only getting battery voltage, 12.6 or less, its not charging at all. For the 2 small wires, (should be marked on back of alt) terminal 1 (excite) should have power when key is on and none when key is off. terminal 2 (sense) should have power all the time. Do you have a GEN light?

Greg,
Thank you for the explanation. I will check that voltage tonight, and also the smaller terminals. I do not believe I have a light. I do however have a guage with a needle for C charged, and D dead or discharged? Out of the full scale, driving home Saturday night, I was about 1/4. Almost on D and very very dim lights by the time arrived to my house.

I do not believe I have a light. I do however have a guage with a needle for C charged, and D dead or discharged? Out of the full scale, driving home Saturday night, I was about 1/4. Almost on D and very very dim lights by the time arrived to my house.

That is a amp gauge. Below is quoted from one of my earlier posts.....


The amp gauge only shows the battery's charge or discharge rate. Starting with a fully charged battery......In a amp gauge car, with the car not running start by turning on items in the car, high beams, fan blower on high, brake lights ect... the more thats turned on the farther the amp gauge will show discharge. With everything possible that was original to the car turned on, the gauge may be close to max discharge. Now turn everything off and start the car, the needle will move towards charge a little (not even to the first line) and may stay there for a min or 2, than settle close to the center mark, about a needles width on the charge side. While driving the car and everything working properly this is where the gauge will normally be. Now turn the car off, turn on the high beams and leave them on for 20-30 min or so to take some of the "charge" out of the battery, then turn them off and start the car. Now that the battery's charge is lower, the amp gauge will move farther towards the charge side. As the engine RPM varies, you might see the amp gauge vary the charge rate as alternator output changes with engine RPM (at idle it may be close to the center mark, at 2500 engine RPM, it may show a medium charge rate. As the battery becomes fully charged it will slowly settle close to the center mark, about a needles width on the charge side. Anytime you see the amp gauge on the discharge side with the engine running means either the charging system is not working or the cars current demand is greater than the alternators output, and you are just running off the battery. This is the same thing as having the GEN light on. On factory high performance cars (Chevelle LS-6's, L-78's, Camaro Z-28's) these cars came with a larger deep grove alternator pulley. alternator output was lower than the the low perf cars at any given engine RPM, battery discharge at idle was sometimes a problem, especially if other accessories was turned on.

O.k. I was pretty convinced that the Alternator was bad. Took it off the car and cross referenced at the Delco Remy Website. It is a 63 amp 10SI,
3-wire with an internal regulator. I opened it up thinking that I could get the rebuild kit for $25.00 and keep the Delco Remy. What I found was adout an inch and a half of burnt-out winding. Taht does not come with the rebuild kit so now I am leaning towards a polished 105 amp Powermaster. Thank you for the knowlege and the help.