1964 C-10 CS130 alternator upgrade

[chevyrestoguy]

I have a 1989 350 with a serpentine set-up that I am going to be using in my '64 C-10. I have read a lot of the tech threads on the CS130 alternators, and I have got the data I need to wire it up correctly.

My question is:
Is there any way to wire up the CS130 and still be able to use my factory ammeter gauge? All of the tech articles I have seen say nothing about ammeter gauges.

[VetteVet]

In order to understand how you can be sure the ammeter will work you need to understand how it works. I have explained this many times and perhaps you have read some of them.

There are two types of ammeters that were used on our trucks. The internal shunt and the external shunt styles. The internal shunt was used on the older model cars and trucks and it has all the current from the battery and the alternator going through it before it powers the key switch and the other circuit loads. I think the last year was 1961 for the trucks. The shunt was inside the ammeter in these and it measured the current directly. They were limited to about 60 amps which is reflected on the gauge from 0 to 60 on the plus and minus sides. Or charge and discharge if you will.

The external shunt was developed to allow more amperage to be used in the system as more power became available and was needed for the toys that we have on these trucks . I.E. Electric fans, larger alternators. stereo amplifiers, etc. This style is wired in parallel with the battery and alternator
and it measures the differential voltage between the output of the alternator and the state of charge of the battery. Basically all it does is tell us if the alternator is charging or not and if it is overcharging. If the alternator is not charging the ammeter will show a drop to the discharge side as it reads the battery voltage as greater than the alternator output.

Now assuming you have the external shunt style the shunt will be between the battery and the alternator output wire but in order to read a voltage differential there has to be separation between these two points. If you look at the diagram posted below, which should correspond with your wiring, you will notice a long red wire at the left side of the picture which runs from the top at the battery to the bottom which is the horn relay. This is the shunt between the battery and the alternator. The horn relay was used as the junction point for all the positive power wires in the engine compartment. Alt. battery and regulator plus the feed wire to the cab.



In the later years starting in 1967 Gm moved the horn relay inside the cab and they simply soldered these four wires together in the harness. The only fuse is the fusible link next to the battery on the passenger fender in the positive feed wire from the battery positive terminal. The junction is shown in the picture below. Remember, the only difference is the type of junction.



Now in order to send the parallel current to the ammeter they used two small 20 gauge wires to feed the gauge. They are also shown in the diagram and they are attached to the same junction bolt as the fusible link and to the soldered connection in the diagram. My only problem with your truck is that I have not seen a diagram on the pre 67s that shows this,but I assume you have them because the wiring is very similar in most respects. These two small wires have a four amp fuse in each of them to protect the gauge and these fuses are housed in a small football shaped rubber container and most of the time when the ammeters don't work one of these fuses is blown. One wire should be solid black and the other is black with a white stripe.



And here's another one.



When you convert to the CS alternator you will not need the voltage regulator so what you do with it and the wiring is up to you, but you will need the brown wire and the red wire or the alternator will not work. The important thing to remember is that the alternator output wire has to go on one end of the shunt wire and the battery positive feed wire must go on the other end. I'm pretty sure that even a one-wire alternator will still allow the ammeter to work if it is wired that way. The same holds true if you intend to install a better junction or a newer style fuse relay box.If you need help on the conversion we can do that when you're ready.