Charging problems

-
273

273

Well-Known Member
Joined
May 14, 2012
Messages
6,903
Reaction score
4,307
Location
Ontario
When I bought my 68 valiant it only charged 12 and used up the battery on its 3 ride home. I swap on another alternator and it charges now but if I rev her up it pegs the meter so I bought new voltage regulator and still does the same thing.
I guessing that not normal. But at cruising rpms it seems to be in the green.

It's been upgraded to 70's plus regulator and duel field alternator.
 
Last edited:
I'm gonna have to check that out
I have a feeling I'm gonna have to go through the wiring front to back on this car.

There's a second fuse panel in here seems to do half the wiring.

Just blew the fuse off the battery and I am stranded while waiting for my dad lol

So no matter what higher rpm shouldn't go over the green charging area on the meter ?

The amp meter in the car stays in the middle.
 
If the voltage regulator is doing its job, you will measure ~14.3 V from its case to the IGN (blue wire, right at Vreg), with engine idling (or slightly rev'ed). If original, yours is the old electro-mechanical type. The terminals are exposed, so easy to touch w/ multimeter leads. If true, your job is to insure minimal voltage drop from VR case to BAT- and from BAT+ to IGN (right at Vreg). Drops are common on the gnd side from rusty sheet-metal screws, and on the high-side from the path thru bulkhead connector (twice), key switch, and fuses. Those voltage drops cause over-charging (BAT- to BAT+).
 
You likely got screwed by the rebuilt you bought. The difference between 69, and 70 and later is that 70/ later has TWO field connections. Lots of these rebuilds have one brush grounded to work on 69/ earlier.

Unhook both brush / field wires. Check continuity to ground from each. There should be NONE

The VR must be grounded.

Once you get the car running, get the engine idle adjusted up to "fast idle" to get an ammeter reading. This shows you have not burnt anything up.
Next unhook one alternator field wire one at a time. Each time should cause the thing to stop charging.

Unhook the VR. Again it should "not charge."

If all this is OK you likely have a bad VR
 
The alternator that's on it now is from my old 5th Ave at idle and fast idle it charges fine but once I up the rpms it goes above green into the red on my test meter. The factory gauge stays in the middle. I've tried two VR I had laying around plus a brand new one and they all do the same. I'll make sure there's a good ground tomorrow.

The wiring is pretty butchered I'm looking right now for aftermarket wiring harness
Found one on amazon 12 circuit made by A Team Performance never heard of them but it's $140.


The old alternator would only charge 12v.
 
Last edited:
I'm having the same problem with my 67 Valiant and still trying to figure it out.
 
Sedanman,
You can get it fixed. We are here for you, but first read the gazillion posts (several each week) about the charging system. And don't fixate on this page since he is using the later 1970's charging system. Step one is to replace your old electro-mechanical regulator with a modern electronic version, if hasn't been done. They are made for the early 1960's system w/ same connectors. I have bought for ~$11 on rockauto. If you keep the original, read the factory manual about popping the case, sanding the contacts and adjusting the spring regularly. Kind of like fooling w/ points (the old "tune-up"), which most here don't do anymore.
 
I know and I appreciate it. I am in the middle of putting the axle back together and swapping springs before I go back to the charging issue again. I don't want to have too many things apart at once. I did use the solid state old style VR and both are new and still the same issue. I did pick up the correct alternator for my car so I will see how that goes.

Picture 4605.jpg
 
Excellent. That is the solid-state Vreg for 1960's systems I was talking about. I like the small shiny flat-pack. You can buy them as a larger black box to look like the original, but the covers vary slightly. Some people re-use their original covers for exact OE look.

Trouble-shooting is same deal as post #4. Vreg strives to maintain ~14.3 V between its case to its IGN terminal. It does this by commanding "more" or "less" output from the alternator by controlling its field current (Kit Carlson says it switches on & off rapidly, which you can see on an O-scope). If you insure there is minimal voltage drop from its case to BAT- and from BAT+ to its IGN terminal, then you should measure close to 14.3 V across the battery posts when idling fast. You can buy a cigarette-lighter voltmeter to monitor while driving. 14.3 V will charge the battery, but not over-charge it to where the water dissociates into O2 & H2 (explosive). With car off, a good and charged lead-acid battery should measure ~12.6 V (not sure about Optima gell type).

Your 1960's type Vreg applies a positive voltage to one field terminal, with the other terminal grounded. Doesn't matter which is which, but insure one is truly grounded and that the Vreg "FLD" wire goes to the other terminal. Early alternators had only one field terminal. There was no spade to connect to on the other brush and its gnd connection was just by having no insulator between the brush and alternator case. But, that is aluminum which corrodes and aluminum oxide (white powder, "alumina") is a poor conductor. Of course, you can use a later square-back alternator w/ 2 terminals. Simply ground one of them. Sand away the white powder first and coat w/ silicone grease, and/or run a dedicated ground wire to a solid ground (as most new cars are wired).
 
The other new VR I have and swapped is the same but has the big black factory cover. The battery is at 12.6 not running.
 
You guys might want to see if you can find some of my old posts. "Roughly" I tend to "think" the system into several areas....

1...Is the alternator good, large enough, and capable of full output?

2...Is the regulator good

3...What is the voltage drop so far as heavy charging current from alternator to battery?

4...What is the voltage drop from battery, through all connections, harness, ignition switch, etc, to the VR? This will cause over voltage

5....What is the condtion of the ground paths? That is the ground path from alternator/ engine block/ battery NEG?

Second, the ground path from VR mounting to battery NEG?

++++++++++++++++++++++++++++++++

To check some of this stuff:

1 and 3, alternator condition and charging line drop:

Set up with voltmeter, a way to vary idle screw, and with engine running fast, jumper the field to battery so it charges "full." That is, disconnect the field connection, and hook a good jumper wire from the alternator field direct to battery.

"A quick check" is to speed up the engine until the battery reads say, 15.5, and turn on all the loads you can. Lights, heater, etc. You should be able to diddle with the idle screw and keep the engine above 14V This will not give you "full output" capacity, that is, whether you have a 35A or 60A or whatever, but it WILL tell you if the one you have is capable.

Now, with battery voltage noted, switch your NEGATIVE probe over to the alternator output stud, leaving the pos probe on the battery positive.

This will give you the voltage drop through the harness on the charging line. Check this with lights, heater, etc, powered on. The voltage reading should be "the lower the better" and not over 1Volt. Lower is better. Higher voltage indicates problems at the bulkhead connector and ammeter.

++++++++++++++++++++++++++++++++++++

If this much looks OK, move to voltage drop at the voltage regulator. "Normalize" system connections, IE remove jumper, re-connect regulator wire at alternator, and see if it's charging and what the battery voltage is. If it does not appear to charge, and or voltage is below 14 and certainly below 13--13.5, then it may be VR

Now disconnect VR connections, and jumper them together. Again run the engine and see if the system will charge. This is AGAIN full field condition, just like the first test. If the thing charges, replace the VR

+++++++++++++++++++++++++++++++++++

With a new VR the system should be looking more normal. Now check for voltage drop in the field circuit.

With the key ON but the engine NOT running, stick your meter probe onto the VR "IGN" terminal. Stab the other into the top of the battery POS post. You are hoping for a very low reading. If the reading is more than .3V (3 tenths of one volt) you are suffering voltage drop in the harness, bulkhead connector, or ignition siwtch. You MUST chase this down, as more and more drop in this path will cause over voltage / over charging at the battery

You can confirm this happening by monitoring battery charging voltage. ANY drop measured in this circuit will ADD to charging voltage. In other words if you measured 1.5V in the test above, and the VR is correctly charging "trying" to charge at 14V the battery willl actually see 15.5 V when running.

++++++++++++++++++++++++

Last check the VR ground path.

With the engine running, stab one meter probe into the battery NEG post. Stab the other into the metal mounting flange of the VR. You again should read VERY little, and zero is perfect. IF not the ground path needs to be improved, AKA body grounding to battery NEG
 
You must log in or register to reply here.
-

Back
Top