Wiring Upgrade Btw Alternator, Starter, And Battery

[tamo3]

Hi,

 

I'm working on upgrading alternator to CS144.

In order to upgrade, I

m thinking about upgrading 12V+ and ground(earth) wiring too.

 

Is this good idea to upgrade to 4gauge wires between alternator, starter, and battery?

 

I wasn't sure it's too fat wire or not.

 

Thanks,

Tamo3

[Captain Obvious]

I wouldn't bother changing the wire sizes there. Is there some reason you think you're in need of thicker gauge there or just thinking that since you're in there anyway? I mean, it won't hurt, but I don't think it's necessary.

 

Remember, just because your alternator is CAPABLE of putting out 80A, doesn't mean that it WILL. It will only do that if you're running 80A worth of load, and that will happen... well, probably never. Hopefully never! 

 

And speaking of which... I'm concerned with the way you've drawn the wiring connection between the alternator and the battery. In the original system, there was a fusible link between the alternator and the battery. I think that's a good idea. I'm much more familiar with the 77 system than the 75, but I took a quick look at the wiring diagram and I think the 75 has one between the two as well.

[Captain Obvious]

I took another look at some of the other wiring diagrams (75-78) and verified that there is never a direct connection between anything and the battery positive except for the starter. Everything else is connected through the a fusible link.

 

Take a look at the 75 wiring diagram and trace the white wire coming off the starter solenoid. It goes one and only one place, and that's to a fusible link. I didn't look back beyond 75, but I did verify 75 through 78. Makes sense to me and I wouldn't change that.

 

I've never looked into the "fuse upgrades" that others have done... Is it standard procedure to eliminate that function as part of the upgrade?

[Zed Head]

Since you're redesigning you might consider the battery as just another load and run a fused line directly to the maxi-fuse block.  I think that connecting the alternator charge wire to the starter lug is just an inexpensive and convenient way to connect it to the electrical loads, for the automakers.  That is actually two unnecessary junctions between the alternator and the loads.  Each one drawing a few milliamps.

 

I moved all of my connections to a central post, and run a separate 12 gauge wire to the battery for charging.  The big cable is used to run the starter, and the wire from the alternator is connected to the central point.  So after the engine starts and the alternator is charging, the current flows directly from the charge wire to the various loads, even the EFI harness power.  My battery terminals have no extra wires attached, except for the ground wire on the negative terminal, and the starter only has the big positive cable.  

 

Just one way to do it.  The connections all stay clean and uncorroded because they're not exposed to the acid fumes from the battery.  Even the maintenance-free batteries vent a little bit.

[grannyknot]

This is what I put together last winter, the mini fuse block was added to accommodate the added load of rad fan, fan controller, fuel pump, high and low beam. It is all working well but now I'm thinking maybe I should have a second look at this set up after reading Capt. Obvious' comment about the fusible link. The big cables for pos and neg are 4ga, the rest are 12ga.

Chris 

[Captain Obvious]

Granny, That's beautiful work, but you're right... You've got the same unprotected connection between the alternator and the battery. Obviously (that's me), everything will work fine under normal circumstances, but it's those unforeseen and unexpected faults that fuses and links help with.

 

I've never looked in depth at any fuse or alternator upgrades until now, and because of that, I've not given the details very much scrutiny. But now, simply by chance, I've been planning some wiring changes on my own car so I have familiarized myself with that part of the system.

 

Do I really really think it's necessary to put some protection in there? Only if something goes wrong. 

[rossiz]

i did a complete re-design of the primary wiring on my '78 - i wasn't happy with the fusible links and all the relays out in the weather. i used marine grade 4 gauge wire and sent it into the cabin, then re-located the relays and a new maxifuse block on the fire wall passenger side. used a length of 1 1/2" x 1/8" aluminum bar mounted horizontally sharing the two bottom blower fan bolts as a mounting bar for the relays, mounted the maxifuse block to a plate made of ABS which i attached to the big white plastic connector block that's up under the dash on the far passenger side. cleaned up the engine bay considerably and got all those vulnerable parts and connections inside out of the weather.

it's been working well and i no longer worry about things failing when i drive in the rain