over-charging problem
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Senior User
Joined: Mar 2003
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From: Port Richey FL.
over-charging problem
I just bought a && F-100 2 weel drive with 4 speed and 302. I put a tester on it and found it to be over charging bad . Then while it was running i took the batt cable off and it ran a whole lot better. I didnt drive it just running in the drive way. Do you think it is the alt or the voltage regulator. The regulator is on the front fire wall next to the radator. I paid 150.00 for it and it has no rust out side just the floor boards , So i guess i got a good deal.
New User
Joined: Jun 2004
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From: mdiapolis, IA
Usually when these trucks are over charging it is the voltage regulator. After you change it put a voltmeter on the battery and see how many volts it has with the engine running. It should have between 13 and 14 volts.
Posting Legend
Joined: Sep 2001
Posts: 30,255
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Actually with a fully charged battery it should be 13.8 - 14.2 Volts.
Removing a battery or alternator cable while the vehicle is running causes a "load dump transient" which is about a 400V spike on the electrical system. This will blow out many components in the electrical system.
Removing a battery or alternator cable while the vehicle is running causes a "load dump transient" which is about a 400V spike on the electrical system. This will blow out many components in the electrical system.
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Senior User
Joined: Mar 2003
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From: Port Richey FL.
meaning the alternator is kinda killing the charging system , since its over charging like that.
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Posting Guru
Joined: Jul 2001
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From: Gainesville, FL
All,
There is a possibility that the battery is shot and the alternator is picking up the slack.
This is why you remove the positve battery cable. To test if the alternator is producing amperage or not. If the alternator is dead the motor will stall.
Since his motor continued to run, then the alternator is charging.
Why is it over charging? Voltage regulator.
If the sides of the battery are bulging or swollen, then the battery has been damaged from overcharging.
There's really not much else to say,
KingFisher
There is a possibility that the battery is shot and the alternator is picking up the slack.
This is why you remove the positve battery cable. To test if the alternator is producing amperage or not. If the alternator is dead the motor will stall.
Since his motor continued to run, then the alternator is charging.
Why is it over charging? Voltage regulator.
If the sides of the battery are bulging or swollen, then the battery has been damaged from overcharging.
There's really not much else to say,
KingFisher
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Joined: Feb 2002
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From: East Bend, Carolina, U.S
I hear that removing the battery cable while the engine is running will damage the alternator plenty. Are you sure it isn't the reconnection of the cable while the engine is running that causes the damage? I have had several batteries over the years that became an open circuit (no continuity) and no damage to the alternator ocurred. I just don't follow how an open circuit can damage the alternator. Maybe what has been observed by lots of people is a dying alternator die after this is done since it was going to anyway.
As heavy as the loads are that are placed on alternators it just doesn't make sense that it would be so fragile and be damaged by a simple disconnection of the battery. I can claim to have done this very thing more times than I can remember and have never killed an alternator. I also did it without shorting out any wires and then reconnected the battery cable after shutting down the engine.
One of these days when I am bored I'll get an old aternator even and see how many disconnection and reconnections it can handle before being ruined all while the engine is running. I'll post what I find out.
As heavy as the loads are that are placed on alternators it just doesn't make sense that it would be so fragile and be damaged by a simple disconnection of the battery. I can claim to have done this very thing more times than I can remember and have never killed an alternator. I also did it without shorting out any wires and then reconnected the battery cable after shutting down the engine.
One of these days when I am bored I'll get an old aternator even and see how many disconnection and reconnections it can handle before being ruined all while the engine is running. I'll post what I find out.
Posting Legend
Joined: Sep 2001
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That 400V spike gets dissipated somewhere. It either finds a ground thru the alternator diodes since they are nearby or thru some other component like the ignition module, or radio etc. I have seen those spikes go as high as 700V also. The amperage behind the spike is huge also. Don't ever remove the battery cable while the engine is running.
A simple voltmeter can tell you if the alternator is charging. Turning on the headlamps and the heater blower each put a 20A load on the system for a 40A total load. If the voltage stays up the alternator is charging. Over charging can be read with a voltmeter alone.
A simple voltmeter can tell you if the alternator is charging. Turning on the headlamps and the heater blower each put a 20A load on the system for a 40A total load. If the voltage stays up the alternator is charging. Over charging can be read with a voltmeter alone.
Lead Driver
Joined: Nov 2000
Posts: 6,635
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From: Albuquerque
You get the spike just as you connect or disconnect the cable. It's kind of like unplugging your computor when it's running. All sorts of stuff can go wrong.
If the alternator is working as hard as it can it can draw down the engine speed at idle. Pulling the cable might reduce the electrical load to normal and thus the mechanical load of the engine.
If the alternator is working as hard as it can it can draw down the engine speed at idle. Pulling the cable might reduce the electrical load to normal and thus the mechanical load of the engine.