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Alternator losing voltage with high boost

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Old 07-28-2018, 04:17 PM
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I like to do this:

Negative battery to frame at the front of truck - 8ga
Negative battery to firewall by brake booster - 8ga
Negative battery to alternator bracket - 1/0ga

Positive battery to alternator post - 1/0ga
Alternator post to red junction box - 4ga

If you have the sensor on your ground wire ( I think 05+ trucks have this) then you need to make sure you run any new grounds through this sensor. You have to get creative if you do it this way, which is why I used a combination of 1/0 and 8 gauge for grounds.
Old 07-31-2018, 08:52 AM
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Originally Posted by ILuvJDM
I like to do this:

Negative battery to frame at the front of truck - 8ga
Negative battery to firewall by brake booster - 8ga
Negative battery to alternator bracket - 1/0ga

Positive battery to alternator post - 1/0ga
Alternator post to red junction box - 4ga

If you have the sensor on your ground wire ( I think 05+ trucks have this) then you need to make sure you run any new grounds through this sensor. You have to get creative if you do it this way, which is why I used a combination of 1/0 and 8 gauge for grounds.
Good stuff. This is definitely a more focused "Big 3." Essentially, you can never have too many grounds. This list makes sure all bases are covered well, and with adequate wiring rather than overkill for everything.
Old 07-31-2018, 04:23 PM
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The battery shop is making cables now. I just had my alternator tested. Of course it tested fine. I personally do not think the wiring will change my voltage drop at rpm, BUT I think it is a good upgrade and needs to be done.

We shall see hopefully tomorrow I will have time to put the cables on.
Old 07-31-2018, 04:48 PM
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Someone must sell alternator brushes with higher tension springs.
Old 07-31-2018, 05:02 PM
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Originally Posted by MikeGyver
Someone must sell alternator brushes with higher tension springs.
Someone else mentioned to me that the brushes were moving away from the armature(??) because of the rpm. And I needed to fix that. I will check into this. I have never disassembled an alternator. Maybe it is time to.
Old 07-31-2018, 05:55 PM
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There is another thread with the same problem. The brushes are bouncing at high rpm, the same as valve float.
Old 07-31-2018, 07:19 PM
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Originally Posted by MikeGyver
There is another thread with the same problem. The brushes are bouncing at high rpm, the same as valve float.
So go to an overdrive pulley? Maybe that is the solution? Slow the alternator down.
Old 07-31-2018, 09:19 PM
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Either a larger pulley on the alternator or a smaller pulley on the crank (under drive).
Old 10-17-2018, 08:18 PM
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I switched to a 66mm diameter alternator pulley, slowed Alternator shaft speed by around 15%
Eliminated the belt " SCREECH " when shifting gears at or near rpm limit.
Still makes a bit over 110 amps at idle speed.
Old 10-18-2018, 02:56 PM
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Originally Posted by Fullpower
I switched to a 66mm diameter alternator pulley, slowed Alternator shaft speed by around 15%
Eliminated the belt " SCREECH " when shifting gears at or near rpm limit.
Still makes a bit over 110 amps at idle speed.
Good to know. Where did you get the pulley? any specific one?


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