Hello,

I recently replaced the alternator, battery in my car but everytime the cooling fan comes on the voltage drops significally. Also when the lights are on and the cooling fan kicks in the voltage meter drops almost to the last quarter of the gauge. Needless to say when i turn my signal lights while my headlights are turned on, the turn signal blinks really slow. Any suggestions?

 

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maybe......however I have a similar problem with my rear defroster. Since I first bought the car 4 years ago I have replaced the alternator and battery because they were bad. Since then I have also added coolant fans from a later car and I have never had a problem with the voltage even with all the fans and headlights on, but when I turn only the defroster on, my voltage drops to approximately 9 or 10 volts.

 

Verify the gauge with a multimeter. Those gauges are not always correct.

 

Except that when the headlights dim and the turn signals slow down their cylces, like in both our cases, it means that there is less voltage....right? (due to the device drawing too many amps??? I'd think that would blow a fuse but ???)

 

He never said the lights dimmed. It's difficult to quantify dimming.... it is completely subjective.

Slow blinking could be another problem. Check it with a multimeter to be sure.

 

have you checked the voltage regulator?

 

The regulators are internal on these alternators. The best way to check is to get a voltmeter and watch the voltage output as you load the alternator.

You can also set the voltmeter to AC volts, and read the ripple voltage that leaks past the diodes. If this voltage is too high, it indicates that one of the diodes is defective. This can also cause low output.


The good news is new brushes, bearings, a regulator, and a diode pack are pretty cheap compared to a reman alternator, and you are sure it's put together correctly.

 

I had the alternator replaced twice already. I don't know if the mechanic is installing the right alternator with the right voltage but the funny thing is that when it first gets replaced ( the alternator ) it won't drain voltage for the first few months or so. Then it starts doing it again. It just drains the voltage when the fan comes on and if I am driving with the lights on then it gets scary because it drops almost to the last quarter on the voltage meter. I know the voltage meter is not accurate as I already tested it but it is off only by 1-2 volts so if it is dropping to the 9 or 10 volts with the lights and fan on then it is not good.

 

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