Not charging

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demondriver7

demondriver7

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so I have a 72 demon last summer no issues this year I noticed the Almmeter wasn't reading in the 14s it was down around 11 then the next time I tried to start it wouldn't so I charged and drove again and still same thing slowly dropping. Then the other day it was charging again back in the 14s. Then today drove again and it was drawing quicker then it had been and so I replaced the altinater and the voltage regulator and still the same thing I have a battery that is a year old and the gauges have been in for 2 years. Not sure what's going on, I also found that my radio fuse was blown I found out cause my blinkers weren't working not if that's related. I run an msd ignition and everything is pretty much new on the car. I hate electrical and so I'm not good at it but if you guys could help out that be awesome thanks

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It sounds like either the Alternator or the voltage regulator. Either one can be a bit erratic like that when they are close to failing. If you are not good with electrical systems, here is what I would do. Take the alternator off, and take it to a car parts store like Advance Auto, and they will test it for you. If it is working well, I would buy a voltage regulator since that would then be the likely culprit. If it tests bad, I'd get a new alternator. Ask them to test the new one before you leave the store with it. If you do replace the alternator, there is still a chance that the voltage regulator is also bad, but you will know that by looking at your ammeter. Good luck. I used to hate electrical systems too, but after reading upon them and fiddling with them, it gets easier.
 
Single field roundback alternator, or dual field squareback.
It will help us help you to know that.

Make sure you have a good engine to body ground, like a ground strap.
If the engine is loosing it's ground to the body it can do what you describe. (works and then doesn't)
 
you have a part time open which is causing the no charge then the high charge as it established contact again & it tries to fast charge the battery back up (this high rate is hard on the overall system & possibly what blew the fuse. seperate/clean the bulkhead halves for a start (metal bristle brush on the male ones & a spare male one (used or NAPA 725147-99cents) for the female ones then spray clean em. check all terminals/connections & alt brushes. Keep driving to a bare minimum till you find the problem area. You might be able to get it when it is not charging & run it at an idle & wiggle terminals & if you reestablish contact you will hear the eng slow down as its speed is pulled down by the load of the now charging alt.
 
harrisonm said:
It sounds like either the Alternator or the voltage regulator. Either one can be a bit erratic like that when they are close to failing. If you are not good with electrical systems, here is what I would do. Take the alternator off, and take it to a car parts store like Advance Auto, and they will test it for you. If it is working well, I would buy a voltage regulator since that would then be the likely culprit. If it tests bad, I'd get a new alternator. Ask them to test the new one before you leave the store with it. If you do replace the alternator, there is still a chance that the voltage regulator is also bad, but you will know that by looking at your ammeter. Good luck. I used to hate electrical systems too, but after reading upon them and fiddling with them, it gets easier.
Click to expand...
So I had my brand new alternator tested and it was bad so I got another and had them test it at the store and it was also bad so the called around and 5 other stores had bad one as well, finally got one that tested good and I'll put it to see if that was the issue I'll keep you posted thanks for the posts guys they are helpful
 
Ammeter and bulkhead bypass is highly recommended prior to replacing parts. These issues can definitely be caused by bulkhead corrosion.

Also, is it a remanufactured alternator? The parts store stuff can be pretty sketchy these days.
 
NOTE EDIT on jumpering field

I would not necessarily believe a store "tester." On the other hand rebuilds CAN be shakey. You should learn to make some tests of your own ON THE CAR. That way you can get an idea if it's wiring, alternator, or regulator.

Intermittents are VERY difficult to run down. You have a voltmeter and not an ammeter? Guessing from your post you were posting voltage readings?

I "roughly" group the charging system into sections:

1 The alternator as a component

2 The regulator as a component

3 The output charge wire circuit, including the wiring from the alternator, through the bulkhead/ fuse link, ammeter, and back out, to the battery

4 The regulator power and alternator field wiring circuit

5..In rare cases, the battery itself can give trouble.

==============================

Start by going over connections.......Battery ground to engine and ground(s) from engine/ battery to body. MAKE SURE the VR is clean, grounded, tight!!

Next, do a "full field" test. Several ways to do this. EDIT Start by disconnecting the green field wire at the alternator, hook a "clip lead" to the alternator terminal just unhooked, and jumper it TO GROUND. EDIT Start and run the engine watching ammeter/ voltmeter. Hook a multimeter to the battery and monitor it. Keep battery voltage below 16V

Slowly bring up engine RPM. Voltage should go over 14 pretty easy. Turn on loads, lights, heater, whatever. Bring up RPM a bit more, it should "keep up."

This is just a quick test. Look for the meter jumping around, which indicates a poor wiring connection or poor brushes contact
 
Last edited:
67Dart273 said:
Next, do a "full field" test. Several ways to do this. Start by disconnecting the green field wire at the alternator, hook a "clip lead" to the alternator terminal just unhooked, and jumper it over to battery. Start and run the engine watching ammeter/ voltmeter. Hook a multimeter to the battery and monitor it. Keep battery voltage below 16V
Click to expand...

say Del
does this apply to all Mopar alternators regardless of year or number of field wires?
And when you "jumper it over to the battery", which terminal would that be?
 
^^ACtually I screwed this up^^

up through 69, "single field" connection (blue) disconnect field wireand jumper the now naked alternator terminal to battery

70/ Later, a couple / several ways

A...Disconnect green, clip that alternator terminal to GROUND But MEASURE the blue / "key on" to be sure you have good solid battery voltage with the green terminal grounded.

B...Disconnect blue at alternator, jumper alternator terminal to battery, and ground green terminal to ground, that is pull green off alternator, ground that alternator terminal

C...To check regulator wiring, unplug regulator, jumper across two regulator terminals on 69/ earlier, this should "full field"

D...On later (70/ later) you can also jumper around regulator plug, and remove the BLUE wire at alternator alternator and GROUND that terminal.
 
67Dart273 said:
^^ACtually I screwed this up^^

up through 69, "single field" connection (blue) disconnect field wireand jumper the now naked alternator terminal to battery

70/ Later, a couple / several ways

A...Disconnect green, clip that alternator terminal to GROUND But MEASURE the blue / "key on" to be sure you have good solid battery voltage with the green terminal grounded.

B...Disconnect blue at alternator, jumper alternator terminal to battery, and ground green terminal to ground, that is pull green off alternator, ground that alternator terminal

C...To check regulator wiring, unplug regulator, jumper across two regulator terminals on 69/ earlier, this should "full field"

D...On later (70/ later) you can also jumper around regulator plug, and remove the BLUE wire at alternator alternator and GROUND that terminal.
Click to expand...
Thanks everyone the problem is fix all good info and help it turned up being the alternator went through 3 before I got a good one thanks again
 
I know you hate electrical, but I agree w/ post 8 that it is much easier to test on the car than to remove it and take to the store, plus you are checking the whole system. Multimeters were very expensive when I first got a car, but no excuse to not have one today. youtube's can explain. If you never worked on the bulkhead connections, the big ALT and BAT terminals will likely melt. Search "MAD Bypass".
 
67Dart273 said:
NOTE EDIT on jumpering field

I would not necessarily believe a store "tester." On the other hand rebuilds CAN be shakey. You should learn to make some tests of your own ON THE CAR. That way you can get an idea if it's wiring, alternator, or regulator.

Intermittents are VERY difficult to run down. You have a voltmeter and not an ammeter? Guessing from your post you were posting voltage readings?

I "roughly" group the charging system into sections:

1 The alternator as a component

2 The regulator as a component

3 The output charge wire circuit, including the wiring from the alternator, through the bulkhead/ fuse link, ammeter, and back out, to the battery

4 The regulator power and alternator field wiring circuit

5..In rare cases, the battery itself can give trouble.

==============================

Start by going over connections.......Battery ground to engine and ground(s) from engine/ battery to body. MAKE SURE the VR is clean, grounded, tight!!

Next, do a "full field" test. Several ways to do this. EDIT Start by disconnecting the green field wire at the alternator, hook a "clip lead" to the alternator terminal just unhooked, and jumper it TO GROUND. EDIT Start and run the engine watching ammeter/ voltmeter. Hook a multimeter to the battery and monitor it. Keep battery voltage below 16V

Slowly bring up engine RPM. Voltage should go over 14 pretty easy. Turn on loads, lights, heater, whatever. Bring up RPM a bit more, it should "keep up."

This is just a quick test. Look for the meter jumping around, which indicates a poor wiring connection or poor brushes contact
Click to expand...
Very helpful thanks my alternator is a stock reman 60 amp I am running a msd box, electric fan, xid headlights and I think I am just running to small of a alternator my ac alternator went out and I replaced with a single pulley one 60 amp I think I need to step it up to 100 to 140 amp one what would you recommend? Thanks for your post it was super helpful and any input from here on
 
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