Discharging
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Joined: Nov 2001
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Discharging
I have a 1974 F100 that seems to be eating batteries. I just replaced the old battery thinking it was dead, but now the new battery doesn't hold a charge. The alternator gauge sits frozen in the middle. Is this the sign of a bad alternator or a bad voltage regulator or both?
If I jump it, I can get it to start-- but the electrical system (lights, signals, etc.) are very weak. If the truck dies in traffic, it has to be re-jumped.
Thanks for you help!
Scott Adolf
adolf@efcom.net
If I jump it, I can get it to start-- but the electrical system (lights, signals, etc.) are very weak. If the truck dies in traffic, it has to be re-jumped.
Thanks for you help!
Scott Adolf
adolf@efcom.net
Posting Guru
Joined: Jun 1999
Posts: 2,415
Likes: 3
From: Comox Valley, Canada
Discharging
Could be the alternator, the regulator, wiring, current limiter, loose alternator belt..... probably more I missed.
You can get the alternator and regulator checked at most Parts Stores for free.
Also if you have a voltmeter, you can check the alt output at the BAT terminal of the alternator. Should be 13.5 vdc at least with the truck running.
If you have 13.5 at the alternator and less at the battery positive it is a wiring problem, or current limiter. If you have the same voltage at the Alt BAT terminal and the battery and it is the same voltage as at the battery positive with the truck off, it is usually an alternator or regulator problem.
Good Luck.
Sparky
ps
Most of those factory ammeters are permanently frozen dead centre, and can never be trusted
You can get the alternator and regulator checked at most Parts Stores for free.
Also if you have a voltmeter, you can check the alt output at the BAT terminal of the alternator. Should be 13.5 vdc at least with the truck running.
If you have 13.5 at the alternator and less at the battery positive it is a wiring problem, or current limiter. If you have the same voltage at the Alt BAT terminal and the battery and it is the same voltage as at the battery positive with the truck off, it is usually an alternator or regulator problem.
Good Luck.
Sparky
ps
Most of those factory ammeters are permanently frozen dead centre, and can never be trusted
New User
Joined: Jan 2008
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Discharging
https://www.ford-trucks.com/dcforum/User_files/mil1ion/3be63c65218c2044.gif
Ford has a history of having bad charging gauges.
Drop by a shop that offers free testing of the charging circuit.
They can tell you in about two minutes.
Another way is to attach a Voltmeter to the battery and rev it up .
If the voltage increases ,the charging system is working.
Next try with some power drain ,like head lights,heater,windshield wipers on ,with the voltmeter attached the amount od voltage should drop ,then when it up the voltage should increase.
If it doesn't go to that shop i told you about earlier.
Dennis
78 F-150 429CJ 465,000 KM.(Original Owner)
68 Mustang 289 Sunlit Gold 80,000 Miles(second Owner)
64 1/2,260 Pre-World's Fair Mustang #8092
64 Fairlane 500 S/C,waiting for a 390 4-Spd
If The Girls Don't Find You Handsome,
They Should At Least Find You Handy!
Ford has a history of having bad charging gauges.
Drop by a shop that offers free testing of the charging circuit.
They can tell you in about two minutes.
Another way is to attach a Voltmeter to the battery and rev it up .
If the voltage increases ,the charging system is working.
Next try with some power drain ,like head lights,heater,windshield wipers on ,with the voltmeter attached the amount od voltage should drop ,then when it up the voltage should increase.
If it doesn't go to that shop i told you about earlier.
Dennis
78 F-150 429CJ 465,000 KM.(Original Owner)
68 Mustang 289 Sunlit Gold 80,000 Miles(second Owner)
64 1/2,260 Pre-World's Fair Mustang #8092
64 Fairlane 500 S/C,waiting for a 390 4-Spd
If The Girls Don't Find You Handsome,
They Should At Least Find You Handy!
Senior User
Joined: Nov 2001
Posts: 239
Likes: 0
From: West Jordan, UT
Discharging
i am having the same problem with my 78 Ford F250. I wanted to know if you had this problem fixed and what you did to fix it?
let me know
Mark Christensen
mlchris2(No Email Addresses In Posts!)
let me know
Mark Christensen
mlchris2(No Email Addresses In Posts!)
Junior User
Joined: Sep 2000
Posts: 78
Likes: 0
From: Sonora
Discharging
I'm having a similar problem with my charging system. It is draining the battery. Everything is new and tested anyway. What's really odd is if I turn on the headlights while testing the voltage, the voltage goes up to 13.55. With the lights off, it's about 12.6-13.0 Is something hooked up backwards or what??? Then the other night it blew the main engine fuse and died all together. Maybe a short? thanks in advance. Bill
'70 F-250 C/S 360 C-6 3.73 EVERYTHING IS NEW
'70 F-250 C/S 360 C-6 3.73 EVERYTHING IS NEW
