Charging system problems, now what?

[pachecoj]

My charging system on my 200ci has been giving me problems. I've been trying to find the cause for the last month or so without any success. It hasn't been a total loss, however, because I've been learning a lot; mostly how NOT to diagnose a charging system. Here is what I've done so far.

The car died on me one night (of course at night right at the end of an unlit exit). I took the alternator into Autozone and it tested out OK. So I replaced the voltage regulator. I did this against my better judgement because both the alternator and the regulator were replaced when I bought the car.

Long story short, I charged the battery, drove the car around for a couple hours, then it died on me again. At this point I jumped the car and checked the voltage at the battery, which was very low indicating that the alternator wasn't charging.

I got the car home and let it sit. I started it up the next day and everything was charging fine. So I am only having issues when the engine is hot. I figured I had an intermediate issue in the alternator and replaced it (again, against my better judgement).

I charged the battery and started it up. I was getting 14.4V at the battery at idle with the new alternator (engine cold). I got in the car and drove for 30 min. The voltage was now 14.2V. I then drove home another 30 min and the voltage was 12.3V. So I am still having the issue with the new alternator.

I did the following voltage drop tests at idle engine hot:
ALT OUT (fusible link) --> BATT+ : 0.5V
ALT CASE --> BATT- : 0.2V

The voltage drop on the negative side is good, although the insulation on the ground strap is pretty ratty with some exposed copper. I might replace that just because it looks like it needs it, but I'm getting good ground.

I was thinking my next step is to swap the battery? The battery was also replaced when I bought the car so I'm kind of done replacing brand new parts. What now?

Jason

 

[61EconoDave]

The last time I had a problem with a car not charging it ended up being a bad ground to the engine. I made a jumper wire from the battery to the engine to test and it made my problems go away. After that, I just replaced the bad wire.

 

[Sy Hollinshead]

My money is on a simle wiring fault. Either a poor connection somewhere, or maybe a wire that is too thin to cope with the load. You say you got 12.3v after half an hour of running.... Where was this measurement taken...? I would run the engine again, and carry out a simple voltage test between the alternator output and an earth on the engine somewhere near where the alternator mounts, ie one of the mounting bolts. This will tell you whether the alternator is working. Then you just work your way back to the battery until you have eliminated all the cables...

Sy

 

[Sy Hollinshead]

Also, have you replaced the belt. It's possible for the belt to wear out and lose a little bit of grip, particularly after a long run....
It may look perfectly ok, but i'd replace it anyway if you haven't already....

Sy

 

[ludwig]

Hey Jason,

Bad ground can mean it looks grounded but there is rust under the contact.

Start at the battery cable and clean up all the electrical contacts with fine sandpaper and a wire brush. Make sure you have good ground at the ground strap from the block to the firewall. Sand off the paint and clean up the contacts with the brush.

Clean up all the contacts on your alt and solenoid and all that stuff with the wire brush as well. Note: disconnect the battery first.

 

[pachecoj]

I'm going to be peeved when I find out that it's a bad wire, after spending about $90 on a new alternator and new voltage regulator when they were already new and good quality.

Jason

 

[dagenham]

There could be a wire broken wire inside perfectly good looking insulation.
Ask me how I know.

 

[PaulS]

First, make sure the belt is tight.
Check battery voltage at the posts. record it.
Start engine and bring RPM to 1000 rpm for all tests that follow.
Check voltage from alternator B+ to alternator case. (call this charge volts) it should be 0.5 to 1.5V higher than battery volts when checked with the engine off.
Check voltage from alternator B+ to battery cable connection at solenoid. (this should be less than 0.5V)
Check the voltage from alternator B+ to main battery cable clamp at battery. (should be less than 0.5V)
Check the voltage from alternator B+ to battery + post (this should be less than 0.5V)
Check the voltage from alternator case to engine ground (the voltage should be less than 0.5V)
Check the voltage from the alternator case to frame or inner fender (this should be less than 0.5V)
Check the voltage from the alternator case to the battery negative cable clamp (this should be less than 0.5V)
Check the voltage from the alternator case to the negative battery post (this should be less than 0.5V)

Any test that shows more than 0.5V is a poor connection and needs to be fixed before continuing the next test.

Fully charge the battery and after it has been off the charger for 1 hour check the voltage - record it.
every hour for the next 4 hours check the battery voltage and record it.
If the voltage at the battery drops below 12.5V the battery is suspect.
Crank the engine over with the coil wire removed from the distributor and 1/8" to 1/4" from a good ground. Crank it for 10 seconds with a voltmeter connected from battery positive post to negative battery post. If the voltage drops below 9.5 volts the battery is bad - replace it.

This is the way to trouble-shoot charging problems

 

[pachecoj]

Thanks PaulS.

Btw, you are really helpful. You've responded here and to some of my posts on the Comet/Maverick forums and all of your responses have always been extremely informative. Thanks again.

Jason

 

[pachecoj]

Well I've finally made at least some progress with this problem. The tests PaulS posted were inconclusive because the system wasn't charging at all. The voltage from the output of the alternator to the casing was equal to whatever the battery was giving out (roughly 12V). So I spent some time online and I found a pretty good resource with some tests here:

http://www.balmar.net/Page64-troubleshooting.html

I also had to spend some time educating myself on how the whole system works. Specifically I needed to learn, what the stator is, what the field is, and how the voltage regulator works. I pretty much understand all that now and I may have found the problem.

The issue I think I'm having is that I do not get any voltage on the ignition wire going to the "I" terminal of the voltage regulator. With the key on ACC I'm not sure if I should get voltage because I'm not sure if I have an oil pressure switch that needs to activate that. But, with the engine running I still get no voltage on that wire. So this tells me that, essentially, the voltage regulator is never activating because it doesn't think the ignition is active.

I then eliminated the voltage regulator by unplugging the connector and shorting the "A+" terminal to the "F" terminal to provide full field. I did this with the engine off. I checked the field at the alternator by placing a screwdriver at the rear bearing and I get a substantial magnetic field. I didn't run the engine in this configuration though because it makes me nervous sending all that current to a full battery, even for a short time.

So now it looks like I have to trace the ignition wire back and figure out why I'm not getting any voltage with the engine running. I do have a few specific questions though:

1) This may be specific to my vehicle, but should I get voltage on the ignition wire with the key in "ACC" and the engine off? Or do I have an oil pressure switch that I need to bypass? I don't have an oil pressure gauge, just an idiot light.

2) Why would an oil pressure switch stop voltage on the ignition wire anyway? Is this a safety thing?

3) Can somebody explain what the stator wire does? I understand what the stator does, but why does a wire have to go from the stator to the regulator? Does it supply voltage? Or should it be grounded?

4) Again on the stator wire. When the regulator was bolted up there was like 6V between the "A+" terminal and the "S" terminal with the engine off and no key. This seemed odd to me and I eventually unbolted the regulator and fashined my own ground from the casing to a bolt on the fender. After that I got 12V between "A+" and "S". Should "S" just be a ground or what?

5) And a magic 3rd question on the stator wire. I have two wires coming out of the "S" terminal. One goes to the stator connection on the alternator. The other one isn't hooked up but I believe it's supposed to be connected to a capacitor that is right there. Should I hook it up and what does this do? Eliminate EMI?

Jason

 

[Axle Roads]

When I was dealing with these issues I found a link on this forum which was very informative. It was madelectrical.com.

Consider the wire which is not hooked up to anything may have been apart of a previous setup. Sometimes previous owners change the location of the voltage regulator.

You def. need that switched power on to tell the VR and Alt to turn on. The can't recieve power all the time or it would wear out.

Consider hooking up a dumy ind. light to your voltage regutator temporarily while your figuring this all out. It will just make your life easier.

Find your main juction block. Where is your regulator sensing voltage. measure there for 14.2 volts. It may be in the wirering or at the starer relay. I made my own with a nut and bolt and a half dozen loop disconnects.

 

[JackFish]

I was thinking my next step is to swap the battery? The battery was also replaced when I bought the car so I'm kind of done replacing brand new parts. What now?

Jason

How long ago was that?
So the battery is brand new?
Is it the sealed type, or can you check the electrolyte?

 

[pachecoj]

Where is your regulator sensing voltage.

I'm not sure how/where the regulator is sensing voltage as I do not have a main distribution block. The alternator output goes directly to the positive terminal of the starter relay, which has the positive battery wire mounted to it. So if it were anywhere it would have to be here. But I think this is the least of my worries as I never get any voltage on the ignition wire, and that has to happen first.

So the battery is brand new?
Is it the sealed type, or can you check the electrolyte?

The battery isn't brand new, but it is less than 2 yrs old. I think it is about a year and a half old. It is sealed.

Jason

 

[Axle Roads]

Your currently stuck with a battery which doesn't hold a charge. Right?

Consider this: You did the right thing by replacing either your alternator or voltage regulator. It doesn't matter which, because after a few months trail and error, of slowly discharging and rapidly charging your battery you have accidentally shorted it's life.

Does that sound logical?