Pawned
N.R.A. Lifetime Member - And damn proud of it
In my 71 duster I had to install a 1972 alternator. Because all the 71 alternators I found were not correct. but the 1972 was perfect
Battery drain issue
- Thread starter demon322
- Start date
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May not fix it, but lets hope it does. I refuse to throw parts at a problem unless im dead sure. Best of luck.
67Dart273
Well-Known Member
Not weird. The one with the grounded field brush is for 69/ earlier, the other is 70/ later, and then "long about" 73 or so, they went to the "squareback" which is an improved design
Plain and simple the parts guy screwed you
Coulda been right box,wrong part. It happens.
67Dart273
Well-Known Member
Wondered that too but same number on alt and box. Same one their website says should work, even went back to 68 and it showed the same configuration with the only difference being single or double pulley. Ordered a 72 and up witch has the two field spades like my old one and apparently is an improved design from what I’ve read here. The square back is listed at 70 amps where the round back was 50.
I’m wondering if the one I had could be the original one. It has a 71 casting date and while it could be a reman, I know I’ve never replaced it in 12 years I’ve had it and the car only had 53k miles.
Looking at the pictures (I pick it up tomorrow) the square back field terminals are located a bit different than the alt I’m replacing. Does it matter which wire goes to which field post? Those wires are green and blue on my car. The blue was closest to the main battery wire on the old one.
Wire placement doesen’t matter. Its just a circuit in/out.
cudajim
cudajim
Good point, but most ammeters have a series fuse built in, mine is 2 amp so it'll blow quickly.
67Dart273
Well-Known Member
Yes but many "cheap" ones don't. I dislike blowing them, LOL, the Fluke ones are expensive!!
Pawned
N.R.A. Lifetime Member - And damn proud of it
If your "phantom" drain on your battery is greater than 2 amps and blows your fuse, you have a major problem.
Depending on the meter there may be a plugin for greater amperage up to 10 amps
Alt is replaced and the battery drain issue is much better, but hasn’t disappeared completely.
Wondering if it could be related to this new problem I’ve noticed. Since the changes, all my lights (headlights, park, tail, even dome and dash) flicker BAD at idle. They get steady when engine rpm comes up but not necessarily brighter.
This wasn’t a problem before. I have installed (and loved) Crackedbacks headlight relay kit as well as his wire around. I don’t think that they are the issue as the flickering lights are a new issue.
Could the new alt output be too high? Sometimes it reads high 14 volts and even 15 at idle. Any thoughts on this new issue?
Thanks again.
Wondering if it could be related to this new problem I’ve noticed. Since the changes, all my lights (headlights, park, tail, even dome and dash) flicker BAD at idle. They get steady when engine rpm comes up but not necessarily brighter.
This wasn’t a problem before. I have installed (and loved) Crackedbacks headlight relay kit as well as his wire around. I don’t think that they are the issue as the flickering lights are a new issue.
Could the new alt output be too high? Sometimes it reads high 14 volts and even 15 at idle. Any thoughts on this new issue?
Thanks again.
I had the very same issue. I had replaced the alt gauge with a volts gauge and that needle twitched at idle. I thought... Diagnose it or just buy a voltage regulator? Since I had pulled this alt', reg', electronic ignition, and more off a 73 Valiant a couple weeks earlier... A new voltage regulator couldn't be a bad move. Cured it.
I had the same thought. I had a new VR laying around so I installed it to see what happened. It did help seem to help some with bringing the voltage back to more normal levels, but the dang flickering issue seems to be just the same.
I just don't know then. Wondering if maybe alt' rpm at idle is the issue? Wondering if battery cables are good? Chassis ground jumper(s) good?
Years ago a friend had repeating regulator failures in a 68 Nova. The lug/terminal on the end of the ground cable was properly bolted to the block. With a slight tug the wire pulled right out. If not for a bit of oily electric tape wrapped on it I wouldn't have found the problem so quickly. Remembering other cases that were silly simple faults, like paint interrupting ground path for example. Good hunting.
Years ago a friend had repeating regulator failures in a 68 Nova. The lug/terminal on the end of the ground cable was properly bolted to the block. With a slight tug the wire pulled right out. If not for a bit of oily electric tape wrapped on it I wouldn't have found the problem so quickly. Remembering other cases that were silly simple faults, like paint interrupting ground path for example. Good hunting.
Alternator rpm at idle, meaning the alt could be putting out too much? Is that something AZ (where I bought it) could bench test if I had it out?
The chassis ground jumper(s). I want to be sure what you are referring to here. Other than the main ground that goes to the battery, the only other one I see is a small wire that goes from the terminal end to the radiator support. Should there be one on the back of the engine to the firewall somewhere? Or are you referencing something else completely.
I will for sure check the neg battery cable. It is bolted to the block but like you say it could be loose at the crimped end. I know it does move around a bit at the terminal end, probably because I’ve had it off and on so many times ha.
I could be way off. But based on my readings it seems the flicker I have is not a low voltage problem like some have experienced. I wonder if the high voltage readings are the clue. Bounces and flickers at idle but still bright. Then steadies with rpms but not noticibly brighter.
Thank you for the reply and for the suggestions.
67Dart273
Well-Known Member
There are several factors. No it can't be bench tested at least by a store tester
"Not enough" at idle might be pulley sizes or design of the alternator. The older "round back" were worse at low RPM than more modern "square back" and some of the more current designs (Denso etc) kick that *** even more
Too high charging voltage is USUALLY voltage drop in either the hot side harness or can be the ground
The way to check for drop:
1....Turn key to run, engine stopped. Put one probe of your meter directly on battery + post. Put the other probe as close as you can get to the B+ (ignition) terminal of the regulator. Do not unhook anything in this test. If you still have a ballast, use the "key" side of that, or probe the blue alternator field wire
You are hoping for a very low voltage, the lower the better. More than .3V (3/10 of 1 volt) investigate. You are looking, normally, for drop in the bulkhead connector, the ignition switch connector, and the ignition switch, or anywhere else in the "path" from battery + to the VR IGN terminal.
2....GROUND. Make this test with engine warm, battery normalized, and first with accessories off, and again with lights, heater, whatever you have powered on. Stab one probe of the meter into battery NEG and the other stab into the mounting flange of the VR
Again you are hoping for a very low value, zero is perfect.
The total of these two readings is ADDED to the regulator set point. In other words if the VR would be charging at a "normal" nominal 14V (13.8--14.2) and say, you have a 1.2V drop in test 1, then the battery will run right at 15.2V
Other causes of too much voltages is (rarely) a bad battery, and once in awhile, a bad VR.
GROUNDING. Look at the front of the pass. side head. You have that/ those same bolt hole (s) at the rear of the driver side head. Buy a "eyelet to eyelet" starter cable, bolt it to the rear of the head, and either a bolt/ nut through the firewall, or something like the master cylinder stud. This will provide a VERY solid ground from battery/ block to body, "chassis."
FLICKER. This can be caused by a flaky mechanical regulator. In other cases it is sometimes caused by a weird "feedback" situation. First thing to try there is the ground cable mentioned above.
If you cannot easily fix voltage drop in the hot side of the harness, one way around it is to cut the blue "ignition run" wire coming out of the bulkhead at some point BEFORE it branches off. Use the end coming out of the firewall to trigger a Bosch relay, power the relay through a breaker / fuse from the starter relay stud, and hook the other cut end of the blue "IGN1" to the switched contact on the relay. This will then provide a solid voltage referenced to the battery for underhood loads, including the VR
Thanks for the info. I do have the newer square back style alt.
I will attempt the drop tests you suggested. I do still have the ballast so test 1 I will use the + side of the battery and the ballast.
I will let you know what the numbers are as I'm not positive about what you mean by adding those readings to the regulator set point.
Sounds like I for sure need to add the ground to the back of the head as you mentioned as I don't see any ground at all at the back of the engine to firewall. Hopefully this will fix the flicker issue.
I will report back. Thanks for the help!
67Dart273
Well-Known Member
Here's how high charging voltage works:
With solid state regulators, they are RARELY the cause of high charging voltage per se
Voltage drop in the harness works like this:
The SENSING terminal of a Mopar regulator is the IGN terminal, the terminal from which the regulator gets it's operating power. This is what "tells" the regulator how much to feed to the battery. It adjusts the charge to keep the IGN terminal at the regulator set point
When warm and normal, that set point is supposed to be 13.8---14.2V. Certainly not lower than 13.5 or so, and certainly not higer than 15 or so
If there is voltage drop in the harness, as with the engine off/ not charging, this is caused by resistance in the entire feed path from battery through all lthe wire terminals, connectors, the ignition switch, ammeter, and so on, until power finally reaches the VR IGN terminal. So if the battery is fully charged at 12.6, and if you read the voltage at the VR at 11.5, there is a 1.2 volt loss between the battery and the VR
WITH THE CAR RUNNING and charging, the VR tries to maintain 13.8--14.2 or nominally 14V at that point where you measured the 11.5. THIS MEANS that when running, and when the VR is maintaining that 14V, THAT 1.1V DROP IS STILL THERE and the BATTERY because it is "1.1V away" from the VR IGN terminal, now is running at 14V +1.1 or 15.1V (example)
A RELATED condition is that this drop MAY NOT BE "stable." That is, a bad connection in the ignition switch or connector, may "arc across" and get "better" with some current through it, or may heat up, arc, and get WORSE!!! This can be one cause of flickering lamps.
67Dart273
Well-Known Member
You are not alone nor unique in this endeavor. When I first got my 67, bone stock with a 273 2bbl/ auto it ran nearly 1.5V high at the battery. This was caused by drop in the bulkhead connector and the ignition switch and switch connector
Thank you for this explanation. It was hard for me to wrap my head around the possible overcharging actually could be caused by voltage drop. Interesting stuff.
Unfortunately, I didn't get to perform the tests you suggested yet as my dad got a new top end kit from edelbrock and yesterday was spent tearing his 440 down in preparation for that. It might be next weekend before I have time to get back out there but I will let you know what I find. I went ahead and ordered a starter cable to use as ground since I didn't have one on the back of the engine at all. I will run the tests and then add the ground and compare numbers. Hopefully we can figure this out soon. Thanks for your time.
Ok. I was too excited to do a pre test once the ground wire came in but after the install I unfortunately didn’t see much difference.
Test 1. Key turned to run. Battery+ to blue ballast post (was same at both actually) 1.26-1.30v.
Same test but checked at blue field wire at alt. 1.48-1.5v.
Test 2. Batt- to VR flange. 0.00 with nothing on. 0.01 with lights and radio on.
Engine running at idle 13.83-14.04 tested at battery.
Thoughts?
Thank you.
67Dart273
Well-Known Member
That is a LOT. To reiterate, if your VR is correctly regulating at 14V (nominal) the "let's say" 1.5V you read will ADD to that, causing the battery to be charging at 15.5V. Also, this reading is not usually stable, meaning it can get worse, or better, as the bad connection changes
Now you need to go "back" through the various points in the system.......the bulkead terminals, the ignition switch connector ......and see where the drop is
So extend you test leads so you can leave one clipped to battery +. With the key in "run" as before, check the voltage at the ignition switch connector, both power coming to the switch and the blue IGN 1 going out. If it is already dropped some at the switch feed, then the problem is "between" the switch and the battery........namely the bulkhead connector
One way around this is to electrically cut the blue "run" wire coming out of the bulkhead. Us the bulkhead side wire to trigger a relay, and feed the other end (engine bay side) of the wire from the load contact of the relay
Hopefully I can avoid cutting the factory wiring and adding a relay but that may be a last result.
So check voltage at both sides of the ignition switch connection for the blue IGN 1 wire?
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