Alternator upgrade
Lead Driver
Joined: Apr 2016
Posts: 7,205
Likes: 1,340
From: Bahstun
Alt sits on a bracket, that sits on the block or font cover and all are dissimilar metal making for galvanic corrosion over time and who would want to clean up that alt mounting bracket by taking it off to install an HO alt?
easy to add in a wire to make it grounded and be sure about it
a .5 ohm drop may not seem like much at first but its like crushing your down pipe to 1 inch when needing FULL POWAH
easy to add in a wire to make it grounded and be sure about it
a .5 ohm drop may not seem like much at first but its like crushing your down pipe to 1 inch when needing FULL POWAH
Super Moderator
Joined: Dec 2011
Posts: 13,305
Likes: 6,080
The alternator may have a great physical & electrical connection to the engine, but the weak link is the ground connections from the engine to the chassis & then to the battery. By adding a direct additional cable from the alternator (or as I'm doing) or one of the mounting bolts just eliminates the possibility of a high resistance path.
I would rather prefer to have a "weaker" ground to the chassis, and an even more pathetic ground to the body.
Since the heaviest electrical load (barring any aftermarket equipment like two way radios, winches, or fancy stereos) that a stock truck endures is for starter and glow plugs, both of which are inherently grounded to the engine itself, that is where I would want my least resistant ground path to exist, so that those loads are not tempted to course through the chassis frame, or worse, the body itself, if the path of least resistance was found there.
Mountain Pass
Joined: Dec 2022
Posts: 152
Likes: 56
Ok, so I measured voltage at battery terminals and then battery to alternator chassis... they read the same
Then resistance between battery and alternator chassis.... My meter can't read that low...and I don't have a micro ohm meter
For all "practical" purposes the resistance is nill.
Then resistance between battery and alternator chassis.... My meter can't read that low...and I don't have a micro ohm meter
For all "practical" purposes the resistance is nill.
Lead Driver
Joined: Aug 2022
Posts: 5,065
Likes: 1,415
From: Oologah, OK
The alternator may have a great physical & electrical connection to the engine, but the weak link is the ground connections from the engine to the chassis & then to the battery. By adding a direct additional cable from the alternator (or as I'm doing) or one of the mounting bolts just eliminates the possibility of a high resistance path.
Fleet Owner
Joined: Jun 2004
Posts: 25,090
Likes: 1,112
From: Rio Rico, AZ.
K.I.S.S.
Run that extra ground cable from the alternator to the battery and completley eliminate any doubts about where that ground circuit has to go to find its way back to the battery. Move on to other things in life and never question it again.
Run that extra ground cable from the alternator to the battery and completley eliminate any doubts about where that ground circuit has to go to find its way back to the battery. Move on to other things in life and never question it again.
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Laughing Gas
Joined: Jun 2013
Posts: 1,097
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From: Yokosuka Japan
as the Far East Judge (Japan Region) I have awarded 9.3 points for this answer. I have deducted .7 points for being too polite.
Tuned
Joined: Oct 2020
Posts: 418
Likes: 178
From: Piedmont of N.C.
Fleet Mechanic
Joined: Nov 2009
Posts: 1,381
Likes: 193
From: Cambs, England
Ok, so I measured voltage at battery terminals and then battery to alternator chassis... they read the same
Then resistance between battery and alternator chassis.... My meter can't read that low...and I don't have a micro ohm meter
For all "practical" purposes the resistance is nill.
Then resistance between battery and alternator chassis.... My meter can't read that low...and I don't have a micro ohm meter
For all "practical" purposes the resistance is nill.
Mountain Pass
Joined: Dec 2022
Posts: 152
Likes: 56
Ohms is the resistance to electrical flow, no matter if it's mili amps or mega amps, zero is still zero.
Ok, so with my calculations, 2/0 will handle 175 amps total, now we all know not to exceed 80 percent capacity on electrical components. 175 amps at 80 percent is 140 amps, just slightly above factory alternator output of 110. 2/0 cable will not handle "hundreds" of amps.
Now with that said, the factory has two 2/0 cables going from the batteries to the block, factory capacity is 350 amps, 280 @ 80 percent, more than enough to handle a 240 amp alternator.
I have two 4/0 cables going to the block, 600 amp total capacity, 480 amps @ 80 percent.
Yes, I am a firm believer in the KISS principle, two 4/0 cables going to the block (where the factory intended) provides more amp capacity than two 2/0 cables going to the block, and one 2/0 attached to the alternator housing.
Ok, so with my calculations, 2/0 will handle 175 amps total, now we all know not to exceed 80 percent capacity on electrical components. 175 amps at 80 percent is 140 amps, just slightly above factory alternator output of 110. 2/0 cable will not handle "hundreds" of amps.
Now with that said, the factory has two 2/0 cables going from the batteries to the block, factory capacity is 350 amps, 280 @ 80 percent, more than enough to handle a 240 amp alternator.
I have two 4/0 cables going to the block, 600 amp total capacity, 480 amps @ 80 percent.
Yes, I am a firm believer in the KISS principle, two 4/0 cables going to the block (where the factory intended) provides more amp capacity than two 2/0 cables going to the block, and one 2/0 attached to the alternator housing.
3rd Gear
Joined: Jun 2024
Posts: 3
Likes: 0
Aluminum ground
I'm trying to understand why the separate ground from alternator to battery? There are 4 bolts holding an aluminum frame alternator to the bracket. Seems to me that there is a lot of grounding surface area already. You also have a ground cable at the lower edge of the block, if you really feel the need to ground the alternator, why not run it to the block ground?
Mountain Pass
Joined: Dec 2022
Posts: 152
Likes: 56
Yes I know that al has a lower conductive capacity than gold or copper, BUT, the conductive path, no matter if it's gold, silver, copper or aluminum is still greater than any alternator available, so it became a moot point. Well unless you have an 800 amp alternator?.
As far as a dedicated ground...is there such a thing on a vehicle? Batteries grounded to the block in two places,,body grounded to the batteries in two places,, block grounded to the body in three places, and frame grounded to the body in two places. Where's the dedicated ground?
As far as a dedicated ground...is there such a thing on a vehicle? Batteries grounded to the block in two places,,body grounded to the batteries in two places,, block grounded to the body in three places, and frame grounded to the body in two places. Where's the dedicated ground?