I have upgraded to an FD alternator. Without radio on, lights off, no subs or anything, when I press the brake, or when my car idles at 750, I am seeing 12.3V or so. Does this mean that something is causing a lot of drain somewhere? Or is that expected?

If not, where do I start? I was thinking about using an amp-meter attatched inline with things to see if when the car is off, what is draining the system. Maybe that would give me an idea?

Thanks!

 

Probably didn't wire the alt correctly or you have a bad alt.

Did you follow the wiring diagram found in the FAQ for FC or just wire in the S4 wiring to the FD alt?

 

I followed the wiring diagram in the FAQ. The alternator is brand new. I didn't buy rebuilt. I bought a new FD alternator.

 

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Does it EVER show 14vdc?????

 

Insane rain out. I'll check as soon as it lets up.

I kinda recall seeing 14 or maybe 14.5V when I installed it. Might still be there.

Thanks for the replies guys!

 

Maybe the voltage regulator... I can't remember the name of the part at the moment.... Hmm.... I'll talk to my shop teacher... I'll remember the name in the middle of the night and I won't be able to find the post. Lol. In older cars the regulator was external of the alternator. The FD alt should have the reg in it though.

Good luck to you!
Scott.

 

Mine is internal. Almost 100%

 

If the two wires are on wrong, it won't excite the field. But if you rev the engine up high, it will self excite and THEN you'll see 14vdc. When it does not excite, you'll see 12 vdc approx.

You can prove this on a series four or series five alternator. Depin the L wire and start the engine. You'll get 12vdc approx. While idling in that state, put the L wire on the alternator. Immediatley the alternator puts out 14 plus volts. Been there, done that several times to prove it.

The above won't apply if you start the engine and it rev's cold to 2000-3000 rpm.......because that self excites the field. But the above applies if the engine is started hot and does not initially rev high.

Perhaps you put the wires on backwards? Here's a hint. Look into the jack on the alternator. Look at it with the locking device for the plug at 12 o'clock. So, looking at it like that, the L wire goes to the right at 3 o'clock and the S wire goes to the left at 9 o'clock.

If you used the stock series four wires, the white/black goes to the right and the Black/White to the left.

 

I'll take a look. Very good chance I may have mixed the wires up. Sounds like something I would do.

Hahah. Thanks a ton!

 

Alternator is hooked up properly. Remembered my SAFC-II has a thingy to show voltage. Maybe not 100% accurate, haven't checked. But, it is reading 13.8V most of the time, and 13.5-13.7 if I press the brake down.

Also, one of the reasons it is reading low at idle is because I was idling between 600 and 650. sometimes sitting down at 550. haha. if I hold it at 700-750, it stays around 13.5V.

 

Any reason why when I first start the car, it will read 14.2-14.4V. Then, at normal operating temp, it goes to 13.7-13.8V? I know hotter = more resistance, but, how can I fix that? LoL.

I have two big 4 gauge wires running from the alternator to the battery. I think they are 4 gauge. Thick stuff.