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Alternator not charging after awhile

Discussion in 'Electronics' started by Nirben, Mar 3, 2012.

  1. Nirben

    Nirben Guest

    Hi!


    Im a new user to this forum from Sweden and i have been having some problems with my st162 (3s-GE) -87.
    The car starts up fine, but after awhile the chargingindicator lits up and i have got to rev very high to get it to charge even a litttle.


    Ive tried several batteries, my dad has checked the wiring and today i tried my alternator from my st165, and it ran fine for awhile but then i got the chargingindicator again ant it almost stopped charging.
    We jumpstarted the car and it removed the jumpcables directly and the car ran like the battery was fully charged again.


    Do you guys have any helpful tips? The knowlege about old celicas in sweden aren´t that good. :)
     
  2. Seank90

    Seank90 Well-Known Member Donated!

    sounds like a fault that only happens when warm, ill think about it...

    i know thats pretty much useless but ill think about it.

    EDIT: Welcome aboard! im sean and post your car up in members section, would love to have a look!
     
    Last edited: Mar 3, 2012
  3. Nirben

    Nirben Guest

    Thanks!

    My ST162 is my daily ride so it´s not in mint condition but well kept for it´s age.

    My project car is a ST165 wich has been restored to almost mint condition, the only thing missing is a new paintjob.
     
    Last edited by a moderator: Mar 4, 2012
  4. Stig

    Stig ST162 Guru Donated!

    Are you saying one alternator is fine and the other isn't or are both faulty?
    Is the voltage 14V when it's running?
    Does the battery go flat when it's switched off?

    If it's both I'd start checking for short circuits or it will destroy your voltage regulator.
    With the car switched off, check for current drain at the battery, fuses etc and disconnect any that are drawing current till you can find the cause.
    Often this is a faulty radio/amp etc the other thing to check is the state of your harness wires, esp on the head
    [​IMG]
     
  5. Nirben

    Nirben Guest

    //Nicklas
     
  6. Nirben

    Nirben Guest

    The alternator i switched to worked for awhile, then it stopped charging like before.
    The voltage when running is 12v~
    The battery dries out after a couple of weeks, or after 50km or such..

    I will check for drains and check the cables again.. maybe those damn rats chewed something of because the car has been standing still all winter..
     
  7. Stig

    Stig ST162 Guru Donated!

    Your alternator should be charging at close to 14v
    Your battery should be at close to 13v.

    This tells me the alternator is dead and you are running on battery power till the battery dies

    Take it in for a free battery & alternator test, they will tell you what the problem is
     
  8. Nirben

    Nirben Guest

    Well yes, but i know the alternator is working. Well atleast it did the last time i ran my st165. Could the "coals" have got stuck? I think it´s named coal in englis.
     
  9. Seank90

    Seank90 Well-Known Member Donated!

    brushes
     
  10. 1fstgts

    1fstgts Well-Known Member Staff Member Administrator Moderator Donated!

    Do you have any aftermarket items in your car? Start there by removing those.

    Next thing to do is to start checking for things that could be drawing current when they shouldnt be. Typically when your car is there should be little current draw. ie: Radio memory, clock etc shouldnt kill a battery.

    What you can do is connect a Digital Voltmeter(DVM) in series with the Positive lead to your battery and your battery itself.(Youll be running your electrical system through the meter.) Most can only handle 10A. DO NOT turn on your ignition. Youll blow the internal fuse in your meter(if it has one) or youll kill your meter. Set your meter to the highest amperage setting. Again, for most off the shelf meters it will 10A DC.

    Your current reading should be roughly less than 250mA(1/4A). If its more than that then start pulling fuses out one by one and replacing them until you drop your current reading down. This will help narrow down what circuit is causing all the issues.

    Heres a quick primer I found on how to measure current. (This was easier than me typing it all out).

    http://www.electronics-radio.com/articles/test-methods/meters/how-to-measure-current.php
     
  11. Seank90

    Seank90 Well-Known Member Donated!

    another way to trace what is drawing current is set your multimeter to Amps, then pull a fuse, place one lead in either side were the fuse should be and see if theres current flowing, if there isnt your good, if there is a significant amount then you can have an idea of whats doing it
     
  12. Stig

    Stig ST162 Guru Donated!

    Either the "coil" armature wire has burned or the voltage regulator has blown, it should show at least 13,5v at the battery when running regardless of the load
     
  13. Spiderman

    Spiderman Well-Known Member

    @ Stig, I had a VK Commodore and the dash light came on so I pulled the alternator apart to discover that ( iirc ) one of the 3 diodes on the 'plate' had blown, I went to an auto elec and he had a second hand one and soldered it in and all was good, it only cost me 20 clams because I did most of the work.

    Do all alternators have diodes ?............ At the end of the day, as you said, I would have it tested.
     
  14. Stig

    Stig ST162 Guru Donated!

    Yes, the diodes job is to convert AC voltage into DC voltage

    AC voltage does a good job of cooking your battery, ECU etc. When checking voltage you should also check for AC inside the DC voltage, anything more than 10v AC indicates a problem with the diodes.
     
  15. Nirben

    Nirben Guest

    Seems like one cable from the alternator was broken so it short circuit the alternator or the diods.

    Im getting some help with the wireing and hopefully that will fix the problem :)
     
  16. Seank90

    Seank90 Well-Known Member Donated!

    glad to hear that you found teh source of your issues!
     
  17. Nirben

    Nirben Guest

    Thanks for the advices! i actually found the repairmanual for the 3S-GTE but the wiring for the alternator looks the same.
    Anyone who want´s the link?
     

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