Charging problem

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Coyote Jack

Coyote Jack

Member #55, I'm old
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This is on my 72 Demon.

For about the last year I have had this annoying charging problem. Sometimes it would charge, (for say 15 minutes), and sometimes it wouldn't, (for say 5 minutes). I couldn't find any loose wires or bad grounds so I decided to replace the voltage reg. When I first started it up it showed close to 40 amps on the gauge and when I revved the engine the gauge would peg above 40 amps. I decided to just drive down the road a quarter mile and back, bad move, I smelled something burning and shut it down, then a very small wisp of smoke came from the gauge cluster. I unplugged the voltage reg and drove it back home. I put my tester on the battery and it showed 12 volts even. I then put the old regulator back on and it would charge normal and then discharge, then charge again like it has for the last year. I then plugged in the new regulator again without shutting the engine off and the gauge was normal, about halfway between the middle line on the gauge and the next one up towards 40. The next thing I did was put a trickle charge on the battery for 5 hours to make sure the battery was fully charged. I then started the car again and the gauge is at the before mentioned position just above the center mark and below the next mark higher. It stays there no matter how high the engine is revved. It does dip when when I turn the lights and heater fan on but never goes below the center mark even at idle.

I don't know much about the electrical system but it seems to me that the regulator needs to have a certain amount of voltage to trigger the alternator and because my battery voltage was a little low when I first installed the new regulator it may not have been triggering the alternator properly.

My question is, (I guess), do you think I am good to go now?

Jack
 
I suspect you have a bad amp gauge. Smoke under the dash can become a fire that is nearly impossible to pee on. Find where the smoke came from and fix it.
 
Take it to a good auto-electric shop and have the system tested. They should be able to do a good load test to check the ammeter. I suspect you may have damaged it during your road test.
 
OK, the first thing to do is isolate the problem to engine side/ or interior side of the firewall

Second thing to do is check the regulator if necessary by doing some simple (temporary) rewiring

PRELUDE: You could have a component problem, IE alternator, regulator, ammeter, or a wiring/ connections problem

SO

First, go over your grounds, make sure the battery is solidly grounded to the block (front mount/ trunk mount?) and make sure you have a good jumper from the block to the body/ frame.

Next, make up a big at least no 10 wire and ADD it to the alternator stud, run it right over to either the starter relay stud or the battery itself.

See if this "cures" the problem. You'll have to check with a voltmeter to see if it's regulating. Check FIRST with a voltmeter before you install the bypass, then after to see the difference.

If this doesn't "do" much, leave the bypass in place, and unhook the regulator "ign" terminal. Now wire a temporary wire from the regulator to the battery in such a way that you can (and will) disconnect it as if it were the IGN switch, IE do not let it sit there not running for more than a minute.

If either of these tests show an improvement, you have a problem with the bulkhead connector, the wiring, or the ammeter or it's connections.

ALSO IN the main under dash harness is a great big multi-wire splice. I've seen at least 3 of these fail over the years, it's a little work, but you might consider tearing into the dash, untaping the harness until you find the splice.

Here's a shot of what all comes together from the 72 manual. If you don't have one you can download one free, here


http://www.forabodiesonly.com/mopar/showthread.php?t=132309&highlight=manual,+download

wire R6A-12BK goes up to the ammeter

wire R6-12BK goes out through the bulkhead, I think to the ammeter

dmtk0o.jpg
 
Thanks for all the info and suggestions guys. I tore into it last night.I found where my wisp of smoke came from. It was the positive, (red wire) that goes to the ammeter. It was a little melted right at the connection to the ammeter. I traced it back and there was no other damage. I then installed a new connector and reinstalled the gauge cluster as I saw no other damage. I then went in the engine compartment and checked all grounds, (again), didn't see any trouble spots and decided to try it again. All is good now, the ammeter needle is just above the center mark and steady as a rock. It dips slightly when I turn the lights on and then recovers to the previous position. It stays the same whether it is idling or if I rev the engine up. I am pretty sure I have the problem solved. I believe this all started with a bad ground on the voltage regulator.
Looks like I will be doing the volt meter upgrade soon.

Jack
 
The first thing that caught my eye was just 12 volts at the battery Jack.
It made me think your battery was real low or has a cell going out.
It should read 12 1/2 volts, sounds like you have it fixed :coffee2:.
But if your battery is about to loose a cell it will work your regulator and alternator allot.
Glad to hear all looks good and up to par :thumbup:
 
memike said:
The first thing that caught my eye was just 12 volts at the battery Jack.
It made me think your battery was real low or has a cell going out.
It should read 12 1/2 volts, sounds like you have it fixed :coffee2:.
But if your battery is about to loose a cell it will work your regulator and alternator allot.
Glad to hear all looks good and up to par :thumbup:
Click to expand...

The battery was a little low from discharging a little more than usual lately Mike. It was a new battery this spring and now reads almost 13 volts with the engine off, so it should be fine.

Jack
 
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