'88 Cavalier not charging

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  #1  
Old 10-17-02, 07:53 PM
Das Boot
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'88 Cavalier not charging

I'm trying to find out why an '88 Cavalier (2.8L) will not charge (or insufficiently charges) with a new alternator AND battery installed! All wires are good and connections are intact as best as I can tell and the grounding is good. The best voltage I see (engine running) is 12.5 V and it continues to drop until the battery is too weak and it stalls. The new alternator has been tested by the supplier and is okay. Yes, I'm stumped!
 
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  #2  
Old 10-17-02, 08:26 PM
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take a closer look at your wiring the wire that bolts onto back side of alternater usually runs through a fusible link at the starter solenoid, your field wire which is on the plug in connector should have power to it with key on, does the battery indicator light up when the key is turned on?
also might check the guages fuse in the fuse panel.
 
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Old 10-20-02, 02:14 PM
Das Boot
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Thanks for the tips, Bejay.

I've checked the wires you indicate, namely they all show continuity when disconnected at both ends. Tedious job! Because of this, I'm satisfied that the fuse links are okay and the wiring is intact. This car has no battery indicator light, rather there is a dash-mounted voltmeter which always reads too low, surprise, surprise. The guages fuse is intact as well.

These cars have a service bulletin issued that warns of insufficient charging due to poor grounding design. Why this should suddenly be an issue in a 14 year old car I don't know. My test of this was to grasp the alternator case with one end of a jumper cable, and directly to the negative battery post with the other end. No luck. Didn't make a difference.

Like I say, the new alternator has been returned to the supplier twice now and passes their bench test. This is a reputable parts company in our town. Even so, unless there's something I'm overlooking, I'm awful leery of that new alternator!

Until further notice, our '88 Cavalier is a paperweight!
 
  #4  
Old 10-20-02, 08:13 PM
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well unfortuanately showing continuity does not mean they are good, run a heavy jumper from back post on alternater to positive of battery see if it charges then, if you have a test light check for power at your field connector with it disconnected usually the small brown wire.
you may have a bad alternater have another parts store test it on the bench.
 
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Old 10-20-02, 08:20 PM
Joe_F
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I agree with BeJay.
 
  #6  
Old 10-25-02, 02:12 PM
Das Boot
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A happy ending! I had a mechanic I know look over the Cavalier and he performed some tests on that new alternator. He confirmed that the new alternator was defective, not charging, and should be returned. Fortunately he knows the guys at the parts supplier and phoned them on my behalf and told them to give me another alternator and not a hassle. Done and done, the new alternator is installed and putting out a nice fat 14.5 volts. I'm sure questioning the validity of their "bench test"! Thanks for all the tips, fellas!
 
  #7  
Old 10-25-02, 03:51 PM
davidf
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das boot -good movie

12.5 volts is not enough to charge the battery.You need about 16 volts to overcome something called the internal resistance of the battery which is a low resistance for a new battery and a higher resistance for an old battery.Idealy,a perfect battery would have no internal resistance and 12 volts would charge it up but in the real world nothing other than theory is perfect.All types of batterys from flashlite to car batterys have internal resistance which is why you always need a little more voltage than the battery rating voltage to charge it.Your problem most likely has to do with your connecting cables or tightness of connections or something is loading down the circuit .If you are using a cheap analog voltage meter to measure the voltage then the reading will be off considerably. Only an expensive voltmeter will be correct ,like what garages have on there chargers.The inexpensive multimeters probable will read 1 volt off from true reading.These cheap multimeters are sold everywhere for 10 to 30 dollars and a good multimeter will cost you hundreds of dollars.
 
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