Charging system issue

Tiny
1997F-250
  • MEMBER
  • 1997 FORD F-250
  • 7.3L
  • V8
  • TURBO
  • RWD
  • MANUAL
  • 203,000 MILES
Well, my voltmeter always reads low and my battery light is always on. I put two brand new batteries in it and just had the alternator rebuilt. Still have the problem. Changed the terminals and tightened them. Problems still there. I am not mechanic, but I am stumped.
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Sunday, January 15th, 2017 AT 11:16 AM

12 Replies

Tiny
CJ MEDEVAC
  • EXPERT
And this puppy runs the batteries flat because Mr. Alternator is not charging the battery?

With a cheap handheld digital voltmeter ($5.00 at Harbor Freight) check out this link from "Repair Guides" at the top of our pages.

https://www.2carpros.com/articles/how-to-check-a-car-alternator

Return with results.

The Medic

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Sunday, January 15th, 2017 AT 8:39 PM
Tiny
1997F-250
  • MEMBER
Alternator is not the problem. We replaced it a month ago and checked it to be sure. It is putting out and working good. If any electrical draw such as headlights, blower, etc. Two brand new batteries in the summer too. Stumped!
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Monday, January 16th, 2017 AT 6:23 AM
Tiny
1997F-250
  • MEMBER
If there is any electrical draw it will drain the battery engine running or not.
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Monday, January 16th, 2017 AT 6:26 AM
Tiny
HMAC300
  • EXPERT
Let me add to this. There are three fusible links and a fuse that can effect this check those with test light or volt meter. It should be same volts on both sides if not the link may be bad, also, if it does more at low rpm check belt and tensioner as replacement for both is suggested at 60,000 miles as the tensioner loses tension and belt will wear. Do not go by cracking on belt it needs a gauge to measure it. If this is a 215 amp alternator then there is a difference and get back to me.
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Monday, January 16th, 2017 AT 7:02 AM
Tiny
1997F-250
  • MEMBER
Brand new serpentine belt and new belt tensioner pulley.
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Monday, January 16th, 2017 AT 10:43 AM
Tiny
HMAC300
  • EXPERT
Check the links I supplied in reply. Unless this is a 215 amp alternator, if it is there are more fuses.
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Monday, January 16th, 2017 AT 12:02 PM
Tiny
CJ MEDEVAC
  • EXPERT
So back to this

The alternator is good AND IS CHARGING THE BATTERIES

There is a parasitic draw draining the batteries over time (like at night)

Does this scenario sorta resemble yours?

https://www.2carpros.com/questions/1989-ford-tempo-98-tempo-bran-new-battery-shut-car-off-didn-t-days-now

Your Turn

The Medic
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Monday, January 16th, 2017 AT 4:08 PM
Tiny
1997F-250
  • MEMBER
Not really no. The batteries hold a charge fine when the truck isn't running. They hold a charge even if it is running as long as i'm not running any electronics. But if it's running with any electrical draw, it kills the battery relatively quick. I really appreciate this help by the way!
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Monday, January 16th, 2017 AT 5:38 PM
Tiny
1997F-250
  • MEMBER
Also it's a single cab diesel dually, it doesn't have any extra ammentities such as power windows, power locks, power seats, etc.
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Monday, January 16th, 2017 AT 5:44 PM
Tiny
CJ MEDEVAC
  • EXPERT
Yep,

Maybe a review again.

Digital Voltmeter (Harbor Freight $5)

Set it to 20 volts DC

Check battery voltage at battery posts - engine off (either battery, don't matter) Example 12.5 Volts

Now crank it up

Check the same battery posts, if the alternator is charging, there will be an improvement in the voltage, Example now it might read 14 Volts.

If there is no improvement, the alternator may be 'good', it's just not reaching the battery.

Beings that you have a Diesel, the only drain it takes is to crank it over (I'm no diesel guy, there may be little goodies that help run it, computer and such)

I can see the "no drain" when running, but when you fire up your headlights and such, you have a drain.

Are we sure the alternator is reaching the battery?

What are your test results with the voltmeter?

Not trying to be a pain, many folks never do the testing, they sling parts at it.

I'm sorta hung up on maybe a fusible link- Need your testing input!

The Medic
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Monday, January 16th, 2017 AT 6:32 PM
Tiny
1997F-250
  • MEMBER
I will test it again sometime in the next couple weeks. I think you're probably right with the fusible links. I'm gonna take it to our local garage and have them fix it. I don't have the skills to do it anyways. I'll tell the mechanic the information you've given me and i'm sure it'll help him. I'll let you know what the problem ends up being. Thank you for all you help sir it is ic appreciated.
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Monday, January 16th, 2017 AT 6:43 PM
Tiny
CJ MEDEVAC
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Be sure to return here with your findings!

We like happy endings!

The Medic
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Monday, January 16th, 2017 AT 6:54 PM

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