Alternator Output

Discussion in 'General Motoring' started by MHolland, Nov 15, 2003.

  1. MHolland

    MHolland Guest

    I bought a '92 Civic in August. Within a week the battery died. Since then I
    have replaced the computer, and the distributor. Today my daughter drove it
    to work. When she tried to drive it home the engine would not crank. I
    jumped it, and it started right up. After disconnecting the jumper cables I
    checked the voltage at the Civic's battery terminals with a voltage meter
    and it read 14.2 volts. When driving it home I heard a high pitch whine that
    seemed to come from under the hood. I took it to Autozone and had the
    charging system checked. They said the alternator was putting out 62 amps at
    2000 rpm and 35 at idle. I think that should be good enough to keep the
    battery charged. Here in Arizona batteries are usually failing because of
    heat (bad cells). This acts like a bad cell to me.

    Thanks
     
    MHolland, Nov 15, 2003
    #1
  2. MHolland

    Tony Hwang Guest

    Hi,
    Make sure you have good main ground connection from battery/alternator
    to car chassis. Hot weather is harder on batteries than cold climate.
    I live in Alberta. Used to go down to PHX a lot. (retired from
    Honeywell). Once I suffered a bad battery on a new rental car. Battery
    literally boiled over.
    Tony
     
    Tony Hwang, Nov 15, 2003
    #2
  3. MHolland

    MHolland Guest

    So 62 amps is ok?
     
    MHolland, Nov 15, 2003
    #3
  4. It could be that the rectifier in the alternator itself is draining
    the battery while it's parked. Mine did that. It put out 14.3V while
    engine was idling, which was normal.
     
    Phillip Weston, Nov 15, 2003
    #4
  5. MHolland

    Joe Cool Guest

    You need to isolate the problem to the battery or a drain on the system.

    A. To check the battery for bad cells, have it load tested at AutoZone with
    a resistive load. You can also pry off the inspection caps and measure the
    voltage of each cell with your voltmeter. The cell that reads a lot lower is
    the problem area.

    B. To check for loads that drain the battery while parked, try removing the
    fuses from the fuse block. See if the problem goes away. IF it does you need
    to figure out which circuit is "stuck on" Look at the brake lights, glove
    box light, etc. To see if the alternator is at fault, you will need to
    disconnect the wires while parked and see it the battery stays charged with
    your voltmeter.


    Good luck.
     
    Joe Cool, Nov 15, 2003
    #5
  6. MHolland

    Eric Guest

    It sounds sufficient. The official spec for my '88 Civic is about 35 amps @
    2000 rpm when hot and about 45 amps @ 2000 rpm when cold.

    Eric
     
    Eric, Nov 15, 2003
    #6
  7. MHolland

    Tony Hwang Guest

    Hi,
    What is the alternator capacity?
    What is the voltage with engine shut off?
    Usually when charging system is acting up, radio in AM mode
    will show lots of whiny noise regarless of tuning dial position.
    Tony
     
    Tony Hwang, Nov 15, 2003
    #7
  8. MHolland

    MHolland Guest

    Autozone load tested the battery I bought 3 months ago. A possible weak cell
    appears to have been the problem.

    Thank You
     
    MHolland, Nov 15, 2003
    #8
  9. MHolland.
    Here is a suggestion on how to check for elect. system drain on battery.
    Simply disconnect the Neg. battery cable end and connect a test lamp between
    the two. Touch the post and cable end together while the test lamp is
    attached form one minute to reset the computer. Now move them apart and
    check to see if the lamp illuminates, if so begin disconnecting fuses till
    the light goes off. You will then know which circuit is causing you battery
    drain. If the lamp doesn't illuminate you have no electrical system draw,
    and it sound like the battery has a problem. Also charge battery and let sit
    over night disconnected from car. If it is weak or dead the next day you
    have an internal drain in the battery.
    Mike the mechanic
     
    Michael Simon, Nov 15, 2003
    #9
Ask a Question

Want to reply to this thread or ask your own question?

You'll need to choose a username for the site, which only take a couple of moments (here). After that, you can post your question and our members will help you out.