sbc charging probs - wiring related - please help

[Heavy Z]

Hello everyone, my problem is this: I took a voltmeter to my battery (trunk mounted) and am only getting 12.5 to the battery while the car is running, I checked the alternator down to NAPA auto and it tested fine at around 14.5-15. So I'm losing it somewhere along the way. The wire that goes from the alternator to the starter looks suspicious - old , worn, and spliced. It goes into my wiring harness (to the fusebox? fusable link? amp guage?) and then the return wire wire comes out in equally bad shape that attaches to my starter. I need to know where these wires go once they disappear into the wiring harness. I'm hoping someone knows without having to split it open. If someone knows where the wires go I could bypass this crappy setup all together. I still need to take a voltmeter and go down the line to make sure this is where I'm losing juice, but based on looks alone these wires must go. Please help, I'm tired of having to re-charge my car every couple weeks.

[Tim240z]

You ought to just run a nice new #2 wire straight to the battery. I don't have any of the OEM harness left, sorry can't help there.

Tim

[Heavy Z]

Thanks Tim, I'd like to do that but need to know what else is on that circuit first. If anyone else knows where those wires go I'd appreciate it.

[GAZRNR]

First you need to use the heavy gauge wires for a battery reloacation with new heavy duty connectors. Summit & Jeg's sell the kits.

 

Once you get your gauge + & - resolved make sure you have a good couple of grounds from the engine to the body.

 

Now-what else runs to/from the battery. I recently finished wiring my 78 for the V8 and here is what I found & did. There is a 10 gauge wire from the pos terminal on the starter that runs to the fusable links(solid white wire). There is a wire from the pos battery terminal to the fusable links. I eliminated the fusible links but used a fuse block and kept the same wiring paths. Hope this helps

 

Rusty

[Heavy Z]

Thanks GAZRNR, here's what I've got so far:

 

First you need to use the heavy gauge wires for a battery reloacation with new heavy duty connectors. Summit & Jeg's sell the kits.

 

Done.

 

Once you get your gauge + & - resolved make sure you have a good couple of grounds from the engine to the body.

 

Done.

 

There is a 10 gauge wire from the pos terminal on the starter that runs to the fusable links(solid white wire). There is a wire from the pos battery terminal to the fusable links.

 

Great, this helps - yes this wire is hooked up to the starter. But the other white wire isn't hooked up to the battery, but is to my alternator. So, instead of using a short, fat cable strait from the alternator to the starter(where I have a 2 guage going back to the battery), my setup is using this white wire to run the charge from my alterternator to my starter and back from there. From what you describe the wire I have on my alternator should go back to the pos battery lead, and use a heavy guage to link the alt & starter. Does that sound right?

[GAZRNR]

Your 1st 2 items; heavy gauge wires and good grounds are good point to start from. Before I steer you in the wrong direction are you still using the fusable links or changed to something else? My 78 had 4 fusable links in the system, 2 in each pod. When I cut open the system to see how the links were wired here is what I found and what I duplicated using a fuse block.

 

The solid white wire (10 gauge) from the starter branched off to all 4 fusable links. The 4 white with red stripe wires were on the opposite side of the solid white wires with the link connecting the each pair of wires. In short you have 4 soild white wires and 4 white with a red stripe wires with some type of fuse in between them.

 

In the original setup there were 3 smaller fusible link wires and one larger one. The larger one is to handle the alternator.

 

I would not run your alt wire thru the starter solenoid but would run it direct to the battery with a fuse in line somewhere where you can get at it if need be. How are you drawing power for the rest of your systems?

 

Hope this helps

[Guest Nic-Rebel450CA]

Hey HeavyZ, if you need any more help with this, shoot me a PM or eMail. I did the wiring in my truck from scratch, so I am familiar with where all the wires go. I am actually planning on re-wiring it with the knowledge I have now so I can throw in some relays, etc. Here is a great resource for what goes where:

 

http://www.rmahc.com/alternator.html

 

If you need a hand, lemme know, you know I live nearby

[Heavy Z]

Thank you very much Nic, I may be in touch soon if my latest attempt doesn't work out...