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tamo3

CS144 Alternator is not charging battery

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I swap alternator to GM CS144 following this thread.

 

However, it seems it's not charging the battery.

 

https://youtu.be/PwZftua0j9I

 

When it's idle or high RPM, battery stays around 12.20v. It supposed to go up to 13.x - 14v while charging.

 

When I put multi-tester on Alternator Positive and connect to battery negative, it shows only 11.48v.

What could be wrong??

 

Thanks for your help in advance.

 

Tamo3

 

 

Edited by tamo3

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Just did a bit of looking. I come from the 240z world so things may be a bit different.

The CS144 should have 6 connections

 

Basic overview for others, pins on the alternator:

 

Output

Ground

Signal

Field

Lamp

P for Stator according to  some diagrams.

 

Output:

The output should be going to a common power point and should be a heavy gauge the starter is used as a junction so it should be a good spot like it looks like you have.

 

Ground:

Ground should be through the case, so if the engine is grounded that should be fine. Sometimes they put a coating that might not be conducive to grounding so make sure it is clean and if you want to be doubly sure you can ground the alternator directly to the starter ground or ground it directly to the chassis.

 

Signal:

This is the signal, should be as close from the battery as you can get.

 

Field:

This isn't used as often, but from what I understand it is a protection circuit for when the battery is disconnected from the circuit of an alternator while it is running. 

 

Lamp:

This is your charge indicator, goes to the alternator light, apparently this should be a switched source

 

P for stator:

Apparently can be used for an RPM gauge. 

 

 

 

By removing the shunt, do you mean the voltage regulator? Did you make sure to connect the correct wires on the plug? Following the guide here?

http://atlanticz.ca/zclub/techtips/alternatorswap/index.html

 

 

 

The datsun harness should have 4 wires, an output, a ground, a signal, and a lamp.

 

The output should be hooked up to the output of the alternator

 

The ground should be hooked up to the alternator, I think modern ones ground through the case, so you can get a bigger terminal for the mounting bolt.

 

The yellow wire which is horizontal on the T connector should be the signal wire connecting to the Signal pin on the GM alternator

 

The black/white wire which is vertical on the T connector should be the lamp wire connecting to the lamp pin. 

 

 

 

As long as the voltmeter is receiving a positive the yellow wire should be fine as listed as long as the diode is in the correct way.

 

I don't see that you have a black/white wire on your diagram.

 

Technically you shouldn't need the earth as long as you have the engine grounded to the chassis or the battery, but you do have it so if you cut off the end and put a bigger terminal you can use one of the mounting bolts to make double sure

 

Output I don't think should be connecting to the ignition that directly nor the combo switch. 

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Of course learning from my mistake it could be something simple like a blown fusible link, or a battery with a bad cell. 

 

You should be able to inspect the fusible link and test for continuity. The alternator and battery you can take to a chain store and they should be able to test both for you.

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10 hours ago, seattlejester said:

The alternator and battery you can take to a chain store and they should be able to test both for you.

 

Learn from my own mistake too and don't get them tested at AutoZone. Maybe it was a faulty test, but I had them test my alternator on an old daily multiple times and it tested good. After going insane checking every single cable I could find for continuity to make sure there wasn't a short, and replacing my old battery, I knew logically that it could only be the battery. Replaced it and sure enough.... it was a bad alternator. 

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Thanks for your input.

Both my battery and alternator are brand new. 

 

Here is more detail of my mod.

Since I installed CS144 alternator, which includes IC regulator. 

 

Here is the original '75 ammeter.

ammeter_sch.thumb.jpg.e8b43dcce9749a5d542e4c698ad63676.jpg

 

I modified like this.

 

mod_75_ammeter.thumb.jpg.c68d5a3e3d21ec35f89e90b18fffd8ef.jpg

 

I removed shunt.

Connect Alternator L to 300ohm register then diode.

I connect the line to Voltmeter charge lamp.

 

Alternator BAT+ is connected to Red/White line which leads to Battery.

Alternator Ground is using 4G wire connect to body earth.

 

 

Here is '77 280z Voltmeter schematic for your reference.

volt_sch.thumb.png.a5a27b679a9a36a13935b1a7dd7663a4.png

Edited by tamo3

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Does the charge warning lamp come on?  

If not, are you sure the diode isn't backwards?   I'm pretty sure you need a voltage at the "L" terminal to excite the field before the alt will start charging - if the diode is backwards then you will get no voltage at that terminal.  Maybe check your voltage at "L" to confirm.

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Hmm something doesn't quite look right on that.

 

From what I've read, you either have a voltage gauge, a dummy light, OR a resistor. Looks like you have all 3.

 

I also would like to see a big gauge wire with a bigger fuse go to the junction, having it feed in front of the fusible link seems like it would limit the amperage.

 

If the alternator and battery are good, it can be one of 3 things.

The wires are not thick enough to carry the current (wires would get real hot, fuses would probably blow)

The wiring is incorrect you have a feedback loop or something

The voltage regulator is not getting the correct signal, so it is not telling the alternator to continue to charge.

 

Found this little diagram.

cs144-alt-jpg.51833

Your diagram doesn't quite match up there.

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45 minutes ago, seattlejester said:

Hmm something doesn't quite look right on that.

 

From what I've read, you either have a voltage gauge, a dummy light, OR a resistor. Looks like you have all 3.

That's a good point - you should probably ditch the resistor, too.   Try shorting across it as a test.

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A simple test of the alternator's function, which would also tell something about the charge lamp wire from the harness would be to run a jumper from the L terminal to the S terminal, right at the alternator.  That will power the L terminal, assuming that S has power.  The alternator should start charging then if it is on proper working order.

 

If it works then you can go back and figure out what's wrong with your harness, with a little more hope.

 

Posting now even though TimZ has replied...

 

image.png.15308955f6a3463056cffbff16a7dbdb.png

 

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Thanks for your advice!

After connecting L to S,

5a44adc05b8d2_Photo27-12-1784358PM.thumb.jpg.f5e7911a028bbd7e8ef9647dcc64b29f.jpg

the battery started to get charged!!!

5a44adc1cc0d7_Photo27-12-1784535PM.jpg.90198e33ba34ecb8043228dbfb1604c6.jpg

 

 

Thank you so much!  It now proof, Alternator is good.

When I remove diode, the result is same. Charge lamp never light and voltmeter is not working. I will remove register for the next test.

 

By the way, If I kept connecting L to S(BAT+), is it safe?

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11 hours ago, tamo3 said:

 

 

Thank you so much!  It now proof, Alternator is good.

When I remove diode, the result is same. Charge lamp never light and voltmeter is not working. I will remove register for the next test.

 

By the way, If I kept connecting L to S(BAT+), is it safe?

 

When you say "remove the diode", did you just remove it or did you short across it's terminals?  Just removing it will not work.  Also try reversing its terminals to see if it was just backwards.

 

 

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when swapping alts to modern GM alt you do away with most of the old wiring and start over. the GM 1 wire alt is the easiest and most used by swappers. with the CS144 L to S and batt is prolly the way I have seen it done most often. with the 1 wire you only need a small light bulb in the control wire to add a little resistance. that wire is known as the exciter wire and that bulb is usually the light you see on the dash when the engine is not running but the key is on.

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14 hours ago, tamo3 said:

By the way, If I kept connecting L to S(BAT+), is it safe?

 

As ben a implies, apparently the L circuit of the GM alternators is sensitive to current.  So, a resistor or a light needs to be in the circuit.  Your test was probably okay on it, but if you ran it that way it might be damaged by heat build up.

 

You should be able to figure out why the wire in your harness does not have voltage.  That wire should have the right resistance since it has a charge lamp in the circuit.  I have heard of the charge lamp burning out.  It's not common but it might explain why you don't have power on the wire.  I don't know exactly where it is in the 75.  In the ammeter most likely.  My 76 has a voltmeter, as does 77.

 

Your 75 does not have the wiring of a 77.  Here's a 75 diagram.  I think that I got it from the atlanticz web site.

 

Also, the charging circuit from the 75 FSM, showing the charge lamp.  Also got that from atlanticz.

 

image.thumb.png.c8a0175dbac1cc89582a6d14e733c95d.png

 

 

 

 

75_280z_wiring.pdf

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Come to think of it, you should also check to make sure that the warning lamp isn't burned out.  A voltmeter should measure close to 0 ohms across it if it's good. 

 

I would also advocate for using the "S" input - this is the regulator's  "sense" circuit, and it represents the point that the regulator regulates its voltage to.  If you leave it as is the alt will work but it will just regulate its voltage directly at the alt output.  If you run a wire to the "S" input, the alternator will adjust its output voltage to achieve the proper voltage at whatever point the wire is connected to, which compensates for any voltage drops you might (will) encounter in the harness.    

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People don't seem to be reading each other's posts.  My images were from what is supposed to be a 1975 FSM.  I've seen discussions about whether it actually is in the cars.  It might be that Nissan used old images but never put the light in the early Z's.  Even the 1972 FSM shows a Charge lamp, and it has an ammeter.

 

I suggested that the Charge lamp might be burned out also.  Maybe Charge lamp and Warning lamp are not the same.  Who knows.  In the 1972 image they call it a Warning lamp, see below, in 1975 they call it a Charge lamp, see my previous post.  Your image is from the models with a "starter interlock",  and they've cut out a portion of the diagram.  The arrow starts from nowhere.  The ones I inserted show the circuit back to the ignition switch.  They all go to "L" on the voltage regulator though.

 

"S" is typically connected directly to the battery positive, at the starter lug, where the positive cable attaches.  If you attach L to S there will be a constant draw on the battery, through the windings.  That will probably drain the battery.  

 

Whatever you decide to do, use your meter to confirm that you have power on the wire.

 

image.png.0110b403182c2a83130df5ead982a565.png

 

 

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On 12/30/2017 at 12:05 PM, NewZed said:

People don't seem to be reading each other's posts.  My images were from what is supposed to be a 1975 FSM.  I've seen discussions about whether it actually is in the cars.  It might be that Nissan used old images but never put the light in the early Z's.  Even the 1972 FSM shows a Charge lamp, and it has an ammeter.

 

I suggested that the Charge lamp might be burned out also.  Maybe Charge lamp and Warning lamp are not the same.  Who knows.  In the 1972 image they call it a Warning lamp, see below, in 1975 they call it a Charge lamp, see my previous post.  Your image is from the models with a "starter interlock",  and they've cut out a portion of the diagram.  The arrow starts from nowhere.  The ones I inserted show the circuit back to the ignition switch.  They all go to "L" on the voltage regulator though.

 

"S" is typically connected directly to the battery positive, at the starter lug, where the positive cable attaches.  If you attach L to S there will be a constant draw on the battery, through the windings.  That will probably drain the battery.  

 

Whatever you decide to do, use your meter to confirm that you have power on the wire.

 

image.png.0110b403182c2a83130df5ead982a565.png

 

 

Yep - sorry I missed where you pointed out the possible burned out lamp.

 

Also, in tamo3's video above it clearly shows a voltage gauge with a warning lamp,  _not_ an ammeter.  So, I would suggest wiring the lamp as it shows in NewZed's wiring diagram - ditch the diode and the inline resistor and just use the lamp (after you make sure it isn't burned out).

 

Wherever you connect the "S" terminal will become the point in the harness where the voltage is regulated to the regulator's setpoint.  As NewZed mentions usually you pick the positive battery terminal for this to keep the battery voltage constant regardless of load.  You want to run a separate wire for this, so that it isn't affected by the current draw through the main battery cable.

Edited by TimZ

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Posted (edited)

After extensive texting with try and error, I broke voltmeter. Also I found out the warning lamp was gone too. Luckily, I have a spare voltmeter.

5a4abb95ecb51_Photo30-12-17114222AM.jpg.1858233d0ad664aaa89c7fdaa8226d00.jpg

5a4abb9a0c6c2_Photo31-12-17120449AM.jpg.b35ef57033e304a9752d4761fc567ef1.jpg

 

Thanks for your advice, NewZed, TimZ.

 

Tim,  '75 280z had Ammeter originally, I installed '77 voltmeter.

NewZed, I have original '75 FSM book. I read through it, but '75 does not have ignition warning lamp at all. That's why I'm having issues to figure out how I can install wiring.

 

I think I found 2 problems.

  • The first one, charge lamp was broken. It was working but somehow the light bulb went out. I replace the bulb.
  • Second thing is that to the wiring to the Voltmeter was wrong. I connected both charge lamp to voltmeter wire together. Actually, I need to the 12V+ constant.

 

So, I re-wire as following.

mod_75_ammeter_Final.thumb.jpg.86587b4b49d4a4fd0058688cd0325881.jpg

 

 

Since I need constant for Voltmeter, I tapped wire from the clock blue wire(12V constant) and black wire to the black (ground)5a4abb9890798_Photo31-12-1710720AM.jpg.ebf89b6556a4c5708769a24a17f0dee0.jpg

 

 

Edited by tamo3

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53 minutes ago, tamo3 said:

Once I turn key to ON position, Charge Warning lamp light up.

Is this expected behavior?

 

 

Yes - the warning light should go off once you start the engine, and you should observe something like 13.8V (or whatever your regulator is set to) at the battery.

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Posted (edited)

Not Tim, but...your video looks right, with the light coming on with the key (current passing from the battery through the charge/warning lamp to the alternator windings) and turning off when the engine starts (current generated by the alternator stopping flow from battery). 

 

But, you should rev the engine to 2000 - 2500 RPM too be sure that the regulator is limiting current.  Z's are notorious for having low output at idle RPM, and it's possible that over-voltage could happen with more RPM.  It should stick at 14.7, your idle voltage by your meter, as you rev the engine.  Up to 15 or so would be okay also.  16's, not so good.

 

Assuming that the regulator is regulating though, everything looks right.  Nice result after a lot of work. 

Edited by NewZed

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Congrats on getting it running.

 

It shouldn't be reading all the time. There should be three wires, a power, a ground, and a read. From the characteristics it looks like you have the read and power wire switched. The read wire can have constant power as it only serves to differentiate from the charge to the ground. The power wire should be on the ignition so that it is off when you pull the key.

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