I still say the rectifier needs some attention.

 

Looks like it was the rectifier. I'm not 100% sure, but when I got it back from the repair guys at the company I bought it from, the rectifier inside was a blue color and I don't remember seeing that before I sent it in.
Now all is well, but my headlights still dim to the heavy bass notes, even with the 18 farad cap I just put in as well...

 

headlight dimming is impossible to full cure. Anytime you pull that much current, that quickly you will get a voltage drop.. as long as your staying above 12.66 volts with the drops..your alternator is doing it's job.

 

I know the problem is resolved now but just to satisfy my curiousity what was the frequency of oscillation you got on your graphing meter? Did it track the engine rpm or was it on it's own? What was the voltage of the A/C component?

 

I can't say I know the oscillation frequency exactly, but I would estimate from the pulsating of the headlights, at least 5/6 times a second, but it was a clipped DC waveform that varied according to engine speed. The peaks and valleys would increase the faster the engine ran. A variation of up to possibly over 0.7v from peak to valley.

It wasn't true AC voltage because it didn't cross the 0 axis into negative, and all readings I believe didn't show over 0.3 volts of AC voltage.

 

why the 18F cap? i'd ditch that and get a second battery now.

 

The second battery would be nice, but can't really say I've got somewhere to put it. I was looking to possibly get a new battery under the hood, that was rated at 14V, but I can't find such a thing.

 

i dont think the cap is doing anything in your set up to be honest.

i dont think there is such a thing as a battery rated at 14v. i think only 8v, 12.5v and 16v.

If you alternator is a 14.5v type you probably would want a 12.5v battery.

 

I don't expect the cap to do much, except reduce the instantaneous strain on the alternator, and give it an extra fraction of a second to react to the load change and filter out stray ac ripples and eddy currents from getting to the amps.

I did end up finding a 14v battery, but can't find any more information on it...
Esoteric Introduces World's First 14-volt Battery System for Car Audio

My charging system is 14.6, and I know it wouldn't be enough to fully top up the battery, but would still hold the overall voltage in the car up higher.

 

ok this some home made battery made out of 2v cells. so you cant probably buy it. you can always make one yourself, would probably be even better than that home made battery you found. just buy some cells and pretty much assemble yourself a battery.


a 12.5v battery would be better than the cap.