charging problems

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glhx

glhx

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I cannot get my car to charge....heres what ive done so far.

replaced the regulator 2 times. has a 76 regulator on it. I get 12 volts running at the field wires. checked to see if the plug was bad.

replaced the alternator with 2 used alternators. Both checked out on 3 parts stores machines. Checked the ground and hot to the battery and the connections on the alternator. wire brushed all the connections. Car wont charge the battery. battery is almost new.

any ideas on what to do next

I also took the negative battery wire off while the car was running and it stalled. the output reads 12 volts at the alternator and the battery. my guess is thats just battery voltage
 
What year is your car? You mention a '76 voltage regulator; are you using '70-up "dual field" alternators, or '69-down "single field" items? What has changed since the last time the charging system worked?
 
it has the dual field wires. On day i was driving and the alternator bearings went out. i put a different alternator on it....this worked for a while and then it stopped charging. I then had the original rebuilt and had them both tested...both tested good. I replaced the regulator with 3 regulators and it still wont charge
 
If you probe the alternator's output terminal with a voltmeter while the engine's running and get 12 volts, your regulator and/or wiring to the alternator isn't doing it's thing. Check for continuity between the regulator and the alternator, since you've pretty much found out that the alternator's are okay.
 
I still have the same issue. I have not had time to look deep into it. I will follow your thread and see what you come up with. Maybe I will have time when I get laid off later this month....
 
the system is so simple. 4 wires a regulator and an alternator. I get no voltage from the output on the field terminals on the alternator.
Im washed in voltage regulator hell......ive put 5 of them on this car .....2 of them brand new and then tested them...they showed bad. just put on #5 and still no luck....took a good one from another car that i know worked and it tested bad. The alternator is testing good.....the wires have been gone through. What else is there
 
Alright, first make sure that the output wire from the alternator (large wire to the stud) actually goes to the battery. With engine off/ key off, you should measure battery voltage there.

Next, get some clip leads, disconnect the field wires, and ground one brush terminal with a clip lead--does not matter which.

Hook your other clip lead to the remaining brush terminal, and then to the battery output stud. You should see a spark, indicating the field is drawing current.

Then start the car, and "ease" up the RPM, see if you show a charge. If not, take your meter, with engine running, measure at the output stud. With meter in place, "ease" up RPM, the voltage should go up past 12, if you continue to increase RPM, should go on up, depending on how low the battery is.

Double check your meter readings at the battery positive post. you should get same voltage within reason.

If there is a large difference in voltage readings between the alternator output stud and the battery positive, there may be a wiring problem (bulkhead connector, broken wire connection, ammeter) that is stopping current to the battery.

To double check this, put one probe of the meter on the battery pos. post, the other on the output stud of the alternator. You will be reading THE VOLTAGE DROP across the wiring harness feeding from the alternator to the battery. If it is charging "bunches" (lots of current) there may be a volt or two difference. If there is much more, suspect harness troubles.

If you can get NO output with the above lashup, then suspect alternator troubles. By using these clip leads, you have eliminated everything except

the alternator

and the harness from the output stud to the battery.

Another way to check this harness, is to make a temporary jumper out of large wire, no 10 or bigger. Hook it from the alternator output stud to the battery positive post.

Repeat the test with the clip leads, and see if you get increased voltage at the battery when revving the engine. If so, of course, you have a harness trouble.

Now, if the first "clip lead" test indicated charge and a substantial rise in voltage, you can switch to the field , regulator, and related harness.

First, maybe the harness supplying 12V in run to the field is dead. Connect the BLUE wire to the field, take your clip lead, and ground the other wire. See if the thing charges, as above with the clip leads. It should put out substantial voltage, and if it does, the blue 12V feed is OK.

Next, "normal" everything back up except disconnect the regulator. Rig a probe into the green wire socket on the regulator and GROUND the green wire. Once again, it should charge "full output."

If so, about the only two things left are the ign supply to the regulator and the regulator itself.
 
i did what you said.....i got it to charge...........It started to over charge....then stopped charging...then over charged....then stopped charging......i drove the car 5 miles....the whole time it didnt charge........got it home.....it over charged.....then the v regulator lost power.....then it over charged...then lost power and didnt charge at all......what is this???? i finally shut it off charging at 18 volts
 
glhx said:
i did what you said.....i got it to charge...........It started to over charge....then stopped charging...then over charged....then stopped charging......i drove the car 5 miles....the whole time it didnt charge........got it home.....it over charged.....then the v regulator lost power.....then it over charged...then lost power and didnt charge at all......what is this???? i finally shut it off charging at 18 volts
Click to expand...

OK, he said a lot. We need to know what you actually did to get it charging?

I think You might have a ground or power wire problem to the regulator.
 
Check your battery, and all grounds. Ground from alt to reg, if erractic, will cause that.
 
A regulator that overcharges is normally either not properly grounded or bad. You may have some wiring harness issues.

FIRST check your ground system. The regulator CASE MUST be grounded same voltage as battery negative. If your battery is in stock location you need main ground wire to block, and a nice big jumper from the block to the body.

Also, erratic charging can be brushes, but those will not cause overcharging.
 
Check if you have a short to ground .Get a multimeter set on "millivolts"(or auto,depending on the meter),put the black lead to the negative of the battery,use the red lead of the meter to check the grounds of the regulator,touch the red lead to the alternator case.Anything over .1 volts means you have a short to ground somewhere.
 
1BadDodge71 said:
Check if you have a short to ground .Get a multimeter set on "millivolts"(or auto,depending on the meter),put the black lead to the negative of the battery,use the red lead of the meter to check the grounds of the regulator,touch the red lead to the alternator case.Anything over .1 volts means you have a short to ground somewhere.
Click to expand...

Sorry, but the above is not correct

You CAN check for proper grounding on the regulator by --sort of-- doing this.

Let's say you have a system that is OVERcharging, fairly stable. That is, not charging and failing like this problem here

With the engine running on "low to med cruise" check first with all loads off, then again with lights, heater on. The battery should be "up."

Put one probe on the battery negative post, the other probe RIGHT ON the regulator case. you should not show MORE THAN .2 (two tenths) of a volt.

YOU ARE NOT checking for a "short." You are checking to see if the regulator is properly grounded to the battery neg.

You can do the same thing with the positive path to the regulator ign/ sense terminal.

Put one probe right on the battery POSITIVE post, the other probe on the ign terminal of the regulator, same as above, engine running.

Once again, the lower the reading the better, and over .2V is too much, and indicates VOLTAGE DROP in the path from the battery to the regulator.

This drop can be caused by loose connections, corrosion, bad bulkhead connector(s), bad connections at the ammeter, bad connections at the ign switch connector, as well as bad contacts in the ign switch itself.

IT DOES NOT, however, test for a "short."
 
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