Voltage issues, bad Alternator?
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New User
Joined: Dec 2008
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From: Baker, MT
Voltage issues, bad Alternator?
Hi very new to the forum world, but not to the 7.3l powerstroke. First off i have a 2000 that I just started to upgrade. I have just put in new edge cs insight to moniter guages and did install the egt probe that came with it. I tuned it with a dp from jody in december. Problem i noticed while learning more about the 7.3l and what i can do with it (on this forum) I noticed that my volts after startup weren't in the range what some have posted. Tonight it took about 1 1/2 minutes for the alternator to show any volts. and when it did it went up to about 13.2 and now on high idle i can only get about 12.3 to 12.8 volts.
Is that where i need to start, have my alternator tested? and what should normal volts coming off the alternator be? thanks for the help
Also if it helps I am in montana and it has been below zero for the last 2 days. Pickup is kept in a garage at 50 degrees
Is that where i need to start, have my alternator tested? and what should normal volts coming off the alternator be? thanks for the help
Also if it helps I am in montana and it has been below zero for the last 2 days. Pickup is kept in a garage at 50 degrees
Laughing Gas
Joined: Aug 2009
Posts: 1,192
Likes: 7
From: Belgrade, MT
voltage
Voltage varies at stages on startup, when the glow plugs are running, its way down. But a warmed up truck sitting idling should be seeing 14.5 volts roughly.
A good start is to clean all battery posts, then all the grounds, and use noalox on the battery posts, its used in residential electric to keep corrosion down.
You nmay have one bad connection, or 1 bad battery.
What part of MT? might be able to hook up and take a look.
A good start is to clean all battery posts, then all the grounds, and use noalox on the battery posts, its used in residential electric to keep corrosion down.
You nmay have one bad connection, or 1 bad battery.
What part of MT? might be able to hook up and take a look.
Fleet Owner
Joined: Jun 2004
Posts: 25,090
Likes: 1,112
From: Rio Rico, AZ.
Yeah, make sure that the glow plug relay is turned OFF before you measure the voltage.
The glow plugs easily draw enough current to overcome the alternator.
At that time the batteries are making up the slack.
2 minutes after startup on a cold winter day, the ECU should release the "on" command to the relay and you'll see the voltage restored.
That particular design is why I converted my GPR control to a manual push button.
Once the engine is running, don't really need the glow plugs except for smoke control.
But driving it does a better job of clearing the smoke vs letting it sit there and warm up.
The glow plugs easily draw enough current to overcome the alternator.
At that time the batteries are making up the slack.
2 minutes after startup on a cold winter day, the ECU should release the "on" command to the relay and you'll see the voltage restored.
That particular design is why I converted my GPR control to a manual push button.
Once the engine is running, don't really need the glow plugs except for smoke control.
But driving it does a better job of clearing the smoke vs letting it sit there and warm up.
Thread Starter
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New User
Joined: Dec 2008
Posts: 3
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From: Baker, MT
After driving around and then shutting it off and later starting it again the alternator is putting out about 14.2 to 14.3, guess it was probably nothing. Now that i have a moniter to check that stuff (cs insight) i just worry more about what i see on the guages. thanks for the replys tho. I will clean up all the grounds and the battery terminals.
Cargo Master
Joined: Oct 2010
Posts: 2,089
Likes: 16
Voltage varies at stages on startup, when the glow plugs are running, its way down. But a warmed up truck sitting idling should be seeing 14.5 volts roughly.
A good start is to clean all battery posts, then all the grounds, and use noalox on the battery posts, its used in residential electric to keep corrosion down.
You nmay have one bad connection, or 1 bad battery.
What part of MT? might be able to hook up and take a look.
A good start is to clean all battery posts, then all the grounds, and use noalox on the battery posts, its used in residential electric to keep corrosion down.
You nmay have one bad connection, or 1 bad battery.
What part of MT? might be able to hook up and take a look.
Fleet Owner
Joined: Jun 2004
Posts: 25,090
Likes: 1,112
From: Rio Rico, AZ.
Also, I've fixed a LOT of charging problems by simply installing some jumper wires between the Alternator post and the battery post.
In addition, a large grounding cable between the body of the alternator and the ground post of the battery.
Latest "testimony" that I can give is an aging 1987 VW Golf GT with the 1.8 gas engine.
Car came in on the hook last week with a dead battery and a new replacement alternator installed by the owner.
Charged up the battery and found that there was only 13.1 volts at the battery at idle with no accessories on.
Found 13.6 at the output post of the alternator.
NO VISIBLE CORROSION at any connection anywhere. Cleaning the posts, etc did nothing to help.
I installed the two cables between the alt and the batt.
Charge rate jumped to 14.2 at the battery posts SIMPLY BY INSTALLING THOSE TWO WIRES.
In addition, a large grounding cable between the body of the alternator and the ground post of the battery.
Latest "testimony" that I can give is an aging 1987 VW Golf GT with the 1.8 gas engine.
Car came in on the hook last week with a dead battery and a new replacement alternator installed by the owner.
Charged up the battery and found that there was only 13.1 volts at the battery at idle with no accessories on.
Found 13.6 at the output post of the alternator.
NO VISIBLE CORROSION at any connection anywhere. Cleaning the posts, etc did nothing to help.
I installed the two cables between the alt and the batt.
Charge rate jumped to 14.2 at the battery posts SIMPLY BY INSTALLING THOSE TWO WIRES.
Thread Starter
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New User
Joined: Dec 2008
Posts: 3
Likes: 0
From: Baker, MT
Thanks for the replies. I will check the grounds and I did clean the battery posts. Any more problems I will return. Thanks again. Lion I live in Baker, extreme eastern MT. But thanks for the offer
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