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Discussion Starter #8
Well this is frustrating. I put the alternator back on and it is still doing the same thing; the volt meter on the dash just sits and fluctuates from 14 - 16 volts at a very uniform pace, not fast just a steady back and forth (14 is the center of the gauge). I put a volt meter on the pos side of the alternator and grounded to see if it fluctuates also - it doesn't. It is a steady 14.46v. The battery with the engine off is 12.something. :dunno: any thoughts?
 

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Well this is frustrating. I put the alternator back on and it is still doing the same thing; the volt meter on the dash just sits and fluctuates from 14 - 16 volts at a very uniform pace, not fast just a steady back and forth (14 is the center of the gauge). I put a volt meter on the pos side of the alternator and grounded to see if it fluctuates also - it doesn't. It is a steady 14.46v. The battery with the engine off is 12.something. :dunno: any thoughts?
Bad gauge?
 

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Discussion Starter #10 (Edited)
Bad gauge?
Don't think so because at night when the lights are on, they pulse from bright to dim, just a little, you about have to look for it to be noticeable, but once you see it, it is pretty obvious. So, I think the gauge is responding correctly. Well, not to mess this thread up; but I put a full charge on the battery and now the gauge is steady, I am thinking the battery may be getting weak.
 

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Well this is frustrating. I put the alternator back on and it is still doing the same thing; the volt meter on the dash just sits and fluctuates from 14 - 16 volts at a very uniform pace, not fast just a steady back and forth (14 is the center of the gauge). I put a volt meter on the pos side of the alternator and grounded to see if it fluctuates also - it doesn't. It is a steady 14.46v. The battery with the engine off is 12.something. :dunno: any thoughts?
Loose ground, bad battery? That's the trouble with cars nowadays ,you have to have them plugged in to a computer to get an analysis of the problem and that costs money!:banghead::banghead::banghead: I would be driving around in my new Tundra by now!:laugh:
 

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Well this is frustrating. I put the alternator back on and it is still doing the same thing; the volt meter on the dash just sits and fluctuates from 14 - 16 volts at a very uniform pace, not fast just a steady back and forth (14 is the center of the gauge). I put a volt meter on the pos side of the alternator and grounded to see if it fluctuates also - it doesn't. It is a steady 14.46v. The battery with the engine off is 12.something. :dunno: any thoughts?
Alternators put out three AC voltage waves 120° apart. That's why there is a diode "trio"; one diode for each "wave" .
Because of the 120° spacing the peaks and valleys are not so pronounced, but you still do not get a smooth DC voltage. Your battery is supposed to also help smooth out the DC voltage.
That is what I would check next (battery), and connections to and from the battery.
 

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Alternators put out three AC voltage waves 120° apart. That's why there is a diode "trio"; one diode for each "wave" .
Because of the 120° spacing the peaks and valleys are not so pronounced, but you still do not get a smooth DC voltage. Your battery is supposed to also help smooth out the DC voltage.
That is what I would check next (battery), and connections to and from the battery.
Yup. My truck did that. Alternator did help a bit, as it was taking 20 seconds to turn on also. That was gone i alternated 13-17 instead of 12-18 . new batteries eliminated it. I never had flickering, but with 2 batteries the not dead one could have covered it. I believe they are isolated when not running. Start and everything else.

Sent from my LGL52VL using Tapatalk
 

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Well this is frustrating. I put the alternator back on and it is still doing the same thing; the volt meter on the dash just sits and fluctuates from 14 - 16 volts at a very uniform pace, not fast just a steady back and forth (14 is the center of the gauge). I put a volt meter on the pos side of the alternator and grounded to see if it fluctuates also - it doesn't. It is a steady 14.46v. The battery with the engine off is 12.something. :dunno: any thoughts?
Can you easily swap a different battery to see if the fluctuating stops? Use your JD battery as a test.
 

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Discussion Starter #15
Can you easily swap a different battery to see if the fluctuating stops? Use your JD battery as a test.
Top post, side post and JD is 12v but small. I drove it this evening and the gauge was steady but the lights being automatic, when they came on, it started right back up.
 

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ZebraFive is correct. But if you are reading 12 volts with no load on the battery, you have a dead, or going dead battery. A fully charged 12 volt battery with no load should read around 13 - 13.8 volts some more than others. 12 volts on a 12 volt battery is a battery going bad.
 

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I wonder if "Shorty" tested the alternator under full load VS it's maximum rating? I've seen alternators with a bad phase charge at partial maximum rated output and cause other problems such as drive-ability, stalling, rough idle, pulsating headlights etc.

A shorted stator winding, open or shorted diode or bad rectifier could cause your lighting problem and still charge the battery at "regulated" voltage. An auto electric expert would test the following to pinpoint a potential problem:

  • Battery load test
  • Alternator maximum amps output VS rated amps output
  • Ripple (AC component over DC)
  • Regulated Voltage
  • Parasitic draw
 

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FWIW
When my daughter had a Cavalier it was a charging/battery nightmare until I finally found a bad fusible link in the wires buried below the alternator/power steering pump. Connection was finally lost when I started tugging on the wires on either side of the fusible links. It ended up pulling apart with only one strand of the multi strand wire left intact.
 
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Don't think so because at night when the lights are on, they pulse from bright to dim, just a little, you about have to look for it to be noticeable, but once you see it, it is pretty obvious. So, I think the gauge is responding correctly. Well, not to mess this thread up; but I put a full charge on the battery and now the gauge is steady, I am thinking the battery may be getting weak.
Kind of agree with that diagnosis, did you do a hydrometer check of each cell?
Almost bet you have one or two "weak sister" cells.

Also if there is a lot of sulfation going on in the battery (white stuff forming between the plates), that can cause plates to
push together and short out.

Just a thought.
 
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FWIW
When my daughter had a Cavalier it was a charging/battery nightmare until I finally found a bad fusible link in the wires buried below the alternator/power steering pump. Connection was finally lost when I started tugging on the wires on either side of the fusible links. It ended up pulling apart with only one strand of the multi strand wire left intact.
That - and a bad ground can cause all kinds of whacky things. I know on Mrs C's Beetle Bug there are 3 different grounds you have to check.
 
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