6.0 alternator
Fleet Mechanic
Joined: Aug 2010
Posts: 1,458
Likes: 156
From: Sedalia, CO
Update after new ground from alternator case to battery, and new 4g wire from B+ to starter relay:
Engine running at idle, no accessories on
Battery voltage 14.42v
Voltage at B+ post 14.49.v
Voltage at larger heavy connector on starter relay 14.42v
Voltage at smaller heavy connector on starter relay 0v
B+ cable very slightly warm
Alternator was pretty hot, but I probably had it running longer tonight, and the batteries started a little lower. (See below.) I'm not sure how much difference that would make.
Engine running at idle, all accessories on
Battery voltage 13.80v
Voltage at B+ post 13.92v
Accessories are lights, brights, driving lights (wired to brights, so seldom used in real life), radio, CB, AC with fan on high.
One other thing that is very different is that the voltage shown on my internal cigarette lighter voltmeter is much higher during the first couple of minute running, when the glow plugs are on, than before. I never used to see much over 11.5v during that time, and tonight after the new cables it was 12.4.
Also, the battery voltage had dropped a few 10ths over night, from 12.8 to 12.5, and I'm wondering if I shouldn't replace them 7+ years is a long time, even for AGMs.
Thoughts?
Mark
Engine running at idle, no accessories on
Battery voltage 14.42v
Voltage at B+ post 14.49.v
Voltage at larger heavy connector on starter relay 14.42v
Voltage at smaller heavy connector on starter relay 0v
B+ cable very slightly warm
Alternator was pretty hot, but I probably had it running longer tonight, and the batteries started a little lower. (See below.) I'm not sure how much difference that would make.
Engine running at idle, all accessories on
Battery voltage 13.80v
Voltage at B+ post 13.92v
Accessories are lights, brights, driving lights (wired to brights, so seldom used in real life), radio, CB, AC with fan on high.
One other thing that is very different is that the voltage shown on my internal cigarette lighter voltmeter is much higher during the first couple of minute running, when the glow plugs are on, than before. I never used to see much over 11.5v during that time, and tonight after the new cables it was 12.4.
Also, the battery voltage had dropped a few 10ths over night, from 12.8 to 12.5, and I'm wondering if I shouldn't replace them 7+ years is a long time, even for AGMs.
Thoughts?
Mark
Veteran/Sheepdog
Joined: Feb 2012
Posts: 6,047
Likes: 110
From: Western AR
As far as your numbers go, they look good at idle. You are still within specs with everything running. Measure the voltage drop from the positive lead of the driver battery to the B+ terminal on the alternator. You should be around .1V if all is healthy in your wiring.
Fleet Mechanic
Joined: Aug 2010
Posts: 1,458
Likes: 156
From: Sedalia, CO
Thanks man. I decided to route the new wire semi-permanently, so I followed the battery harness wire across and to the starter relay, with a 200a circuit breaker on the passenger's fender well. I'm going to have to leave this way for awhile but, if I understand correctly, all the original wire is carrying is current to the glow plug module, and the AIH relay (AIH deleted), and some percentage of the voltage to the batteries.
So I'm clear, I measured the B+ voltage with the ground probe on the driver's battery, and the battery voltage between the two terminals of the drivers battery. Are those the numbers you are suggesting I compare?
Mark
So I'm clear, I measured the B+ voltage with the ground probe on the driver's battery, and the battery voltage between the two terminals of the drivers battery. Are those the numbers you are suggesting I compare?
Mark
Veteran/Sheepdog
Joined: Feb 2012
Posts: 6,047
Likes: 110
From: Western AR
Yes, it will give you the difference in voltage between the two points. This tells you how much voltage was "lost" to resistance from the wiring or components between the two points.
Positive lead on positive battery terminal...negative lead on B+ post on alternator.
Positive lead on positive battery terminal...negative lead on B+ post on alternator.
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