today i noticed a rather weird whistle it almost sounded like a small turbo i opened the hood reved the engine and heard what sounded more like a humm with the hood open comming from the alt then i noticed that the batt gauge was reading extremely low just into the red i went to autozone and got it tested the dude said that it was reading 13.97v but the diode pattern was bad (looked it up cant figure out what it means) he also said that hes never heard of that even on bad alts what the hell is wrong with my car

 

Is ur belt worn or loose? if not sounds like u need a new alt


An alternator creates AC. The voltage regulator (diodes) inside the alternator changes that to a regulated DC voltage for the car

 

u probly have one diode going or gone or a bad connection in the alt somewhere.

 

The Diode Triode is one of the important part of the altenator. It is one of the major componets that converts the AC voltage a generator output in DC voltage. If the Diode Triode fails the result is normally an overheating of the altenator then complete failure. Normally the process is very quick, yours seems to be hanging in there.

Long story short you need a new alternator. I would be worried about it also. Since you alternator is not following a "normal" failure route its very hard to predict how it will fail. The last thing you want is to have the alternator shoot a big voltage spike thru your elctrical system. Your diode triode is one of things that make sure the voltage going to your car is right. On the old school altenators its a $4 part and takes about 20 minutes to change.

 

If they're getting a bad diode pattern, then your alternator needs to be replaced or rebuilt (depending on your skill level). The alternator generates AC power (same as the Alternating Current in your house). That's why it's called an alternator btw. The diode pack inside then converts it to DC (battery) power. When the key is off, the diodes also prevent battery power from draining back through the windings of the alternator, which would discharge the battery and leave it dead. The voltage regulator and diodes are two totally different parts with different functions. The regulator acts like a fast on-off switch which regulates power output as needed.