Alternator to battery post or starter relay on for

[Walmill]

About to do a 3g upgrade on my 94 f150. Stock alternator is connected at the fender mounted starter relay at the post thar receices the positive cable from the battery. Most of the guys I see doing the 3g upgrade connect the alt to the battery post instead.
Not counting cable length/configuration space cosmetics etc is there any functional difference between connecting it to the battery or to the relay?

 

[Chris142]

If the battery tends to gas it will corrode the wire sooner. That's likely why the oems go to a junction such as your relay.

 

[bullwinkle]

As long as the connection at the starter solenoid/relay is good, it shouldn't make any difference. I'm sure it was a Ford cost decision not to run it all the way to the battery positive terminal.

 

[BrocLuno]

Mostly it depends on conductivity. All the OEMs use crimped cables only due to speed of MFG. But over time, the crimps develop crevice corrosion and can have up to 0.3v drop across the crimp to wire/cable. So if you count the number og crimped ends between the alternator and the battery post, you can see it is possible to loose significant voltage.

On all the Fords I have done, I always run a #8 wire with crimped and soldered lugs from the Bat Neg (-) pinch bolt directly to the alternator mount. That gives the voltage regulator a much better reference so the charging system will act more as designed. Often times this is enough to get the OEM system putting out enough to keep up with demands ...

If the factory cables are in good shape, clean them with wire brush, use some plumbers flux to get through the tarnish from age that you can't wire brush, and solder the crimped ends directly to the cable. Once this is done, there is effectively no difference between the Bat Positive (+) and the Motorcraft starter solenoid with OEM configuration.

OBTW - please do not ever replace that starter solenoid (relay) with a non-OEM grade unit. I had one go bad and put a NAPA Blue Streak replacement in. Almost burned down the COSTCO gas station when it welded ON and started toasting the wires when I started so I could pull away from the pumps. A bunch of guys jumped to help me push it out of the bays before a disaster.

Since I have read many comments on the F-150s and Big Bronco forums about how these systems will eat/weld aftermarket solenoids. I installed a correct Motorcraft P/N unit and all good ever since

 

[Linctex]

My Ranger connects the main alternator lead
through a fusible link
to the battery post of the relay on the fender.

It's been that way for 290,000 miles.

 

[Walmill]

Originally Posted By: Chris142
If the battery tends to gas it will corrode the wire sooner. That's likely why the oems go to a junction such as your relay.


Makes sense. Will keep current wire path.

Originally Posted By: BrocLuno
Mostly it depends on conductivity. All the OEMs use crimped cables only due to speed of MFG. But over time, the crimps develop crevice corrosion and can have up to 0.3v drop across the crimp to wire/cable. So if you count the number og crimped ends between the alternator and the battery post, you can see it is possible to loose significant voltage.

On all the Fords I have done, I always run a #8 wire with crimped and soldered lugs from the Bat Neg (-) pinch bolt directly to the alternator mount. That gives the voltage regulator a much better reference so the charging system will act more as designed. Often times this is enough to get the OEM system putting out enough to keep up with demands ...

If the factory cables are in good shape, clean them with wire brush, use some plumbers flux to get through the tarnish from age that you can't wire brush, and solder the crimped ends directly to the cable. Once this is done, there is effectively no difference between the Bat Positive (+) and the Motorcraft starter solenoid with OEM configuration.

OBTW - please do not ever replace that starter solenoid (relay) with a non-OEM grade unit. I had one go bad and put a NAPA Blue Streak replacement in. Almost burned down the COSTCO gas station when it welded ON and started toasting the wires when I started so I could pull away from the pumps. A bunch of guys jumped to help me push it out of the bays before a disaster.

Since I have read many comments on the F-150s and Big Bronco forums about how these systems will eat/weld aftermarket solenoids. I installed a correct Motorcraft P/N unit and all good ever since

Scary about the relay getting stuck. I had replaced to an offbrand relay that quickly gabe me issues and replaced it back to a new motorcraft. I've upgraded all my main battery cables already to 0gauge only have the alternator setup to complete. I will add in the bracket to neg connection you mention.