Voltage regulator or Alternator?

[Luis911]

I have a problem of very intermittent voltage for one week. 2 months ago I put a capacitor of 2 farad for the sound. Today I made several tests, while it managed in the night I went seeing the voltage of the capacitor, when the voltage works well the capacitor it marks 13.5 volts and suddenly low the voltage to 9-10 volts, the instrument panel is darkened and the gauge of the alternator marks that same value approximately, after some minutes the voltage ascends like to 11 volts but it continues a little dark the instrument panel, minutes later the voltage is regularized and everything works well, this can last well 15 minutes or 10 seconds, it is intermittent. Another test, when I start the car the voltage it is well, but when putting first gear and to advance suddenly low the voltage (1200 rpm).

 

[MustangLX-5.0]

Let me see if I'm understanding this correctly.You are connecting a 2 Farad audio capacitor to your amplifier.You say the voltage reads 13.5 volts then it drops down to 9 or 10 volts.You then say in the morning when you start the car up,put it in first gear and start moving,the voltage drops while the RPM's are at 1200?

There are many possibilities for this.One of which could be a short or bad connection in some wiring anywhere in the car.Meaning a wire someplace could have an open end and be touching a ground which would cause your voltage to drop a lot.This could also overheat some wiring and start a fire or damage your alternator.Another possibility is yes..your alternator.Or perhaps the regulator.But I would rule the alternator out for now.First check for any loose wiring.Check your amp connections and make sure there are no wires touching where they shouldnt be.

 

[Luis911]

Let me see if I'm understanding this correctly.You are connecting a 2 Farad audio capacitor to your amplifier.You say the voltage reads 13.5 volts then it drops down to 9 or 10 volts.You then say in the morning when you start the car up,put it in first gear and start moving,the voltage drops while the RPM's are at 1200?

There are many possibilities for this.One of which could be a short or bad connection in some wiring anywhere in the car.Meaning a wire someplace could have an open end and be touching a ground which would cause your voltage to drop a lot.This could also overheat some wiring and start a fire or damage your alternator.Another possibility is yes..your alternator.Or perhaps the regulator.But I would rule the alternator out for now.First check for any loose wiring.Check your amp connections and make sure there are no wires touching where they shouldnt be.

my English is not good. sometimes when the car is detained and I advance when arriving to 1200 rpm approximately the voltage it falls to 9 volts and it stays this value. the problem is intermittent, in the day or in the night, with or without lights, I already disconnected the sound and it follows the problem.

 

[bennettracing]

To the best of my knowledge, all of the alternators used in our vehicles have an internal voltage regulator, so the repair for this will most likely be the same answer, which is to replace the alternator. It is possible that there is an issue with your charging circuit in general, the alternator requires voltage that passes through your charge meter on the dash (which has a certain resistance) and then it will charge the system. The voltage readings you are getting, while a bit on the low side, really aren't that drastic. A short in the system would probably start blowing fuses or melting wires, so I wouldn't think that would be the problem, but anything is possible.

If I might make a suggestion, don't worry about hooking up the capacitor, 2 Farad's really aren't that much unless you really want to put it in. I have seen much greater results with the addition of a second battery, or upgrade the existing battery to a much higher quality battery such as an Optima red top. While expensive, both of my vehicles have seen considerable electrical improvements after adding this battery.

A far fetched idea that could be causing your problem would also be that you have a battery that is becomming faulty. Wouldn't hurt to have it checked out!

-KB

 

[HISSIN50]

Some foxes use external regs but most aero fox regulators are indeed internal. They take 2 minutes to swap out.


There's a decent chance that your reg is bad. I dont throw money at parts but it's not a bad thing to have a spare regulator around anyways. I would try replacing yours if you feel like it. Some of the aftermarket regulators out there don't last too long.

We assume that you dont have car-part stores that can test parts for free. If you indeed have free testing like that, have your alternator tested.


And regarding the path of alternator switching: voltage goes through the battery-light to excite the alternator.
Also: Voltmeters, by definition, have inherently high resistance (in the mega-ohms magnitude) so they don't affect the circuit in a meaningful way.

 

[Luis911]

Have problems no longer been presented , does the voltage stay stable in 13.5 volts (seeing the display of the capacitor), it is not logical, was the problem intermittent, did the problem disappear?.
If there was a short circuit that voltage value would have the battery?, is the display of the capacitor as a voltmeter and was the drop in value of 9 volts.

 

[bennettracing]

If you are using the capacitor's display as a voltmeter, that could easily be your problem. Capacitor's that come with the display have an adjustment screw on them so that you can make them read whatever you want them to. If this is the case, get ahold of a multimeter and check your voltage at the battery and see what it says.

-KB