well i searched and all i could find were people with to little voltage being put out. my question is what is wrong when your putting out over 15 at 2500 rpms. i noticed it and one guy told me it was ok but id feel better seeking more peoples opinions. with the lights and radion on though it drops to around 14.2 any input would be nice. thanks


billy

 

i wish i can get that... im only at 12.5 with car on thats with a new battery

 

You're good to go, man...If it hits 15.5 or over, then start worrying (or if your bulbs start blowing, lol)...If you have a fully charged batt, and hardly any electrical loads on, you'll see 15, depending on ambient temperatures...

 

all 12 volt cars should be at a minimum of 12.6 volts off, 13.5 volts running. If your car is not, you have a charging system problem.

They should not be past 15 volts at any time. If the car is running above 15 volts, electrical devices like the CPU and ECU will start to fail as well as bulbs will end life prematurely.

 

Mark, I would like to direct your attention to the S4 FSM, page 5-3, which states that the alternator output voltage should be between 14.4 and 15 volts...Now, common sense dictates that 15.1v is not all of a sudden gonna blow everything up. However, as I stated above, at 15.5 I would start being concerned...Enjoying my bright-*** headlights, but concerned nonetheless...

 

Does the voltage swing dramatically with RPM changes?

If you're uncomfortable with it (I would be), take the alternator in to any auto parts store to have it tested. The voltage regulator could be going bad.

-=Russ=-

 

my voltage output increases as the throttle does. ill check the alternator this weekend. now charging system problem, what could that consist of?

 

Within parameters, it will increase as armature rotational speed increases, but the voltage regulator should prevent seeing anything much above 15 volts, or it's not doing its job. There is also a resistor circuit to drop your 12 volt input to a field excitation voltage (somewhere around 1.5 volts), but if that was screwy, your output would be catastrophic, and I wouldn't consider 15.2 volts or so to be catastrophic. Like Icemark said above, the life of some electrical components will shorten, especially bulbs...

 

Most likely you have a bad voltage regulator if it swings with RPM. It should pick a voltage and stay there, regardless of RPM (except possibly dropping half a volt or so at a low idle).

The S4 voltage regulator is internal to the alternator. It's possible to replace it, but probably a lot easier to just replace the alternator.

-=Russ=-

 

well it wont hurt to give it a try autozone is around the corner. thanks for the input. if anythings comes up ill come back running.

billy