Voltage drop when the fan is on

[SBSerpent]

Originally Posted by Moritz55

I agree .. Fans drop voltage and amperage quite a bit. I did find that my Alternator needed a GND cable added so that it performed better. I have a Powermaster 105amp (17294) alternator.. It's a 1 wire alternator which required 8gauge wire ground. The original install did not have a GND cable!

This made a huge difference under load... mine went from 14.2V at 900rpm down to 13.4V at my battery with Lights ON and Fans ON ... but still charging the battery!

May be wise to confirm you have a solid GND to chassis or block as insurance... just a thought.

Only two wires attached to my alternator - thick red one on the backside and a thinner red one with yellow stripe on a connector attached to the side. Doesn't appear to be any ground wire. How and where do I attach a ground wire?

[Moritz55]

Originally Posted by SBSerpent

Only two wires attached to my alternator - thick red one on the backside and a thinner red one with yellow stripe on a connector attached to the side. Doesn't appear to be any ground wire. How and where do I attach a ground wire?

SBSerpent, the back half of the Alternator requires Grounding. There should be a threaded hole for a GND Screw... ~5/16" dia size...
If you can get a 1inch long machine screw, Washer, GND cable , Star Washer you are all set. Note put the Star Washer between the GND Cable and Back case of the Alternator. Then the Washer and Screw Head complete the sandwich.
The Front of the Alternator with the Belt/Pulley assembly is insulated from the back since Alternator cases are made of 2pieces.

Then run your cable (if 0.25" dia cable, it may be actually 8gauge which is good up to 6ft of length) to the chassis GND or the GND on the Solenoid. Also use a Star Washer between your Cable, Solenoid post/cable you are attaching it to...

Keep us posted on the results....
Good luck...

[Gaz64]

Originally Posted by Moritz55

SBSerpent, the back half of the Alternator requires Grounding. There should be a threaded hole for a GND Screw... ~5/16" dia size...
If you can get a 1inch long machine screw, Washer, GND cable , Star Washer you are all set. Note put the Star Washer between the GND Cable and Back case of the Alternator. Then the Washer and Screw Head complete the sandwich.
The Front of the Alternator with the Belt/Pulley assembly is insulated from the back since Alternator cases are made of 2pieces.

Then run your cable (if 0.25" dia cable, it may be actually 8gauge which is good up to 6ft of length) to the chassis GND or the GND on the Solenoid. Also use a Star Washer between your Cable, Solenoid post/cable you are attaching it to...

Keep us posted on the results....
Good luck...

Please explain, since the two case halves are bolted together when assembled. The rear case is grounded through the assembled through bolts.
Gary

[SBSerpent]

Originally Posted by Moritz55

SBSerpent, the back half of the Alternator requires Grounding. There should be a threaded hole for a GND Screw... ~5/16" dia size...
If you can get a 1inch long machine screw, Washer, GND cable , Star Washer you are all set. Note put the Star Washer between the GND Cable and Back case of the Alternator. Then the Washer and Screw Head complete the sandwich.
The Front of the Alternator with the Belt/Pulley assembly is insulated from the back since Alternator cases are made of 2pieces.

Then run your cable (if 0.25" dia cable, it may be actually 8gauge which is good up to 6ft of length) to the chassis GND or the GND on the Solenoid. Also use a Star Washer between your Cable, Solenoid post/cable you are attaching it to...

Keep us posted on the results....
Good luck...

Can I ground to the engine block?

[Gaz64]

Originally Posted by SBSerpent

Can I ground to the engine block?

Both halves of the alternator case are already grounded to the engine block.
The large negative lead is already a good enough path to the battery, if it is good enough for starter motor current.

[Moritz55]

Originally Posted by SBSerpent

Can I ground to the engine block?

Yes... you can Ground to the engine block...
It must be clean(no oil/gaskets etc...) so it's a solid connection....

Just as a side note... My Chromed Powermaster Alternator was NOT grounded to the block...with my Roush engine there were Plastic Bushings between the Front mounting Case of the Alternator and engine block. So having a reliable solid ground is very worthwhile.