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Do I need a new alternator?

'99 Nissan Altima

Battery wasn’t fully charged when I tested it, hope that doesn’t make a difference. It’s a very cheap battery, and I’m going to replace it anyway.

Battery dies frequently.

Car hasn’t been started in about five days. It started fine today, and I started it to put it in the driveway. Then I shut it off.

Put multimeter on battery, it registered 12.43 v and dropped rapidly from there. 12.36 after about a minute and kept going. I then started the car. It registered 13 something, then dropped rapidly. Down to about 12.72 after about 30 seconds. Started revving and up to 13.

Let idle and turned on fan and highbeams - 12.82. Then revving- 12.75. Stayed at 12.75 at idle.

Turned off fan and headlights, still at about 12.75.

Turned off, and 12.65 and dropping rapidly. 12.43 after about a minute. 12.34 after 30 seconds more.

Assuming you are in the US you can have Auto Zone test your battery and alternator for free. That will give your answer.

The battery should read 12.4-12.6 volts just sitting.

When the engine is started, the charging system should provide at least 13.8 volts in order to charge the battery.


Okay, alternator needs replacing.

Does anyone have a recommendation for a replacement? I’m going to do it myself.

Is there a local auto electric shop that could repair the one you have? That’d be my first choice, being retired, with a second car, liking to do the work, support local businesses, and to save money.

We used to have shop nearby that didn’t rpair cars but just rebuilt you starter, alternator or generator, usually while you waited. What you got back was far superior to the lousy rebuilt one you get now.

Alas, the cheap rebuitts put him out of business.

I remember when Chrysler Corp came out with the alternator in 1960, you coudl buy new brushes for 25 cents and change them in a minute, right on the car with a Phillips screwdriver/