1997 Sentra Alternator only lasts about a year?

Very irritating. The regulator fails so I have to pay $90 or more a rebuilt.  I'm going to rig a rheostat inside the car to manually control the rotor current while monitoring the battery voltage with a digital display all for far less than replacing the alternator. Any advice or comments?

11 Answers

  • Anonymous
    4 weeks ago


    Unless you fully know what  you are doing, might even cause electrical fire.

    A "rheostat" is insufficient description. They come in tenths of ohms to megohms, milliwatts top many  hundreds of watts  .Youd  have to experiment just to find one in correct range. so..dont. I have calculated resistor values Just to have it fail in practice. That happens, too.Id simply get an OEM regulator and put it in. Not that hard to rebuild an alt or starter. 

    And as said; goofing with a pot while watching a meter is Distracted driving. Law doesn't care Why.

    REF: Electronics tech 40 years. fixed switching/analog power supplies 8 years. There ARE solid state Regulators, you know. 

    And YES, rheostats ( or rather. Potentiometers) DO work on AC if load is pure resistance.. You are controlling the DC field excitation, anyway. Rheostat is in series to control current; Potentiometer in parallel to adjust voltage.

    . Alts. again are Fused and Current Limited. You can short one out, no damage.

    Reversing usually blows fuse. It must be cheap Chinese parts, in his  case. A Chinese reg/rect for my Honda failed very soon. A 20 year old ND  unit still works after4 years..

  • Anonymous
    1 month ago

    The regulator controls the dwell time of the rotor voltage, not varies the voltage or current. 

    Your idea won't work. 

    Where is the regulator?

  • 1 month ago

    Quit messing around. Rebuilt alternators from Advance Auto have a life time guarantee.

  • 1 month ago

    That sounds like something I would try.With your mindset,you certainly realize that there are unknowns that pop up at the most inconvenient times when experimenting.I compliment you on your creativeness.

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  • Anonymous
    1 month ago

    Dude, she's 23 years old. Let her die. You've got a short in the alternator connection.

  • 1 month ago

    I don't know about now. But it used to be (around your cars year) that rebuilt alternators for Nissans were nothing but problems. Put in a brand new Nissan alternator and I would lay money that the problem goes away. Or at least next time buy NAPA gold and collect on the warranty. 

  • 1 month ago

    Something else is wrong, overworking the alternator. Your suggested remedy is not reasonable and won't fix the problem. A weak battery or high powered amp could overwork the alternator, causing early failure. Have your alternator fully tested before shucking another Benjamin on the parts counter and spending an hour under the shade tree swapping in another rebuilt. Have your battery load tested. Clean the cables, especially all the grounds, and tighten them all. If you have a high power stereo or sub amp, make sure your car has enough power to run it and all the other accessories at the same time, without killing the battery.

  • Anonymous
    1 month ago

    $100 car batteries are guaranteed for 60 months(5 years) they do go to 7 yr. then they be dead. So 23 years old means you should be on your 4th battery.

    . if you have been doing the jumper cable routine then YOU BLEW OUT YOUR ALTERNATOR.  1 time cross connection blows out the diodes in the alternator. There is 3 and it needs them all to work to get a sufficient charge to the battery and lights-and horn,etc.

    . If you are always buying a used battery then it is always needing a full recharge meaning the alternator works overtime just trying to get a charge into the battery.

    It is ALL YOUR FAULT.   Start with a new battery, a refurbished alternator and you are good.  Stop using jumper cables because you or your helper is shorting out your alternator. The "good Samaritan thing" sometimes just does not pay.  You helped them for free but you blew up your alternator ($400)

    Rheostat won't work on AC current besides that is what the regulator does inside the alternator.

    I know, you don't.

  • James
    Lv 4
    1 month ago

    Sounds about right for a cheap alternator. Better off buying from the dealership the first time so you don't have to go back and change it again

  • 1 month ago

    Don't do it.  Manually controlling anything while you're supposed to be driving can only lead to disaster because you  will be distracted from driving as you monitor that voltage.

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