I figure that the car stereo guys would know the most about this, so this is why I post my question here.

I have had a problem with my charging system for a couple months now, all beginning a few months after I installed my stereo.

At first, everything worked fine. Then, I noticed a significant dimming of the lights when my sub would hit, and decided I needed a capacitor. Because it was the only one I could find locally, I purchassed a 2-farad unit which is probably overkill for my small dual amp setup. (Infinity Kappa Perfect 6.5" component speakers up front, Kappa 6.5" coax in the sail panels, Kappa Perfect 10.1 sub in the back, MTX 404 amp for the highs, MTX 8302 amp for the sub, and the 2-farad cap) [http://www.theheadfl.com/amprack.htm has some pics and specs if I was unclear on anything]

Anyway, some time passes and I start noticing my voltage being lower at idle. I blamed my battery after the car sat for a week without being driven and then refused to start, and my battery was 3+ years old. So I bought an Optima Red Top (yes I know some of you probably think they suck ) and installed it. It seemed to help a little bit, but I couldn't be sure.

So I took my alternator to Autozone and put it on the tester. They swear up and down that it is working fine. They said it tests out fine. So I took it home and reinstalled it. Then I took off all the ground and power connections I could find and sanded down all the dirt and grime so that they were clean. Then, I sanded the paint off down to bare metal under the ground connection, and cleaned all the other connections I could find. That helped a little bit.

Then, summer starts arriving and I start running my A/C. Well, I notice that running my A/C just makes the charging problem even worse. Long story short, but, at the end of a long road trip, my crank pulley parts separated and the outer ring spun freely over the inner pulley (Basically, it didn't spin the accessories anymore). Apparently it had been questionable for a little while. I get it replaced with a new one, and now I think it was fixed. It seemed alright for a bit, but I still notice that running the A/C leaves me at only around 13V or so. I used to see more, especially at night.

Then, in a move that I now regret, I installed my electric water pump that I had been waiting to install for months because I mistakenly believed the pulley fixed the problem.

Now, a couple weeks later, my situation is basically this. At startup, I see 14V or so, maybe a bit more. Then, as the engine warms up, the voltage settles down to 13.5V or so. Then, as I drive, it gradually moves down, very very slowly. After maybe an hour of driving in the city with the A/C on, I am seeing 12.5 V or maybe 12.0V. I worry that I am dragging down my battery badly. Also, I think the lower voltage is probably spinning my water pump slower.

Anyway, could my alternator be the problem, and would I benefit from a high-amp part, or do I need to look elsewhere. I am woefully ignorant of most things electronic related when it comes to cars. All the diagnosis I could do was check with a multimeter and the voltages are pretty close to what the dash guage is reporting.


Help is appreciated.

-TheHeadFL

 

Smells like a failing Voltage Regulator to me..

If the store says your alt is fine, that'd be the next thing to look at...

 

I thought the voltage regulator was in the alternator??

 

It is, but if it's fine when it's cold, and your voltage dies off when it's hot, makes sense to me.

 

I would say voltage regulator/alternator... basically the regulator is inside the alternator. A high-amp unit may help, and probably wouldn't hurt anything but your pocketbook.

I run a 200A unit that I got off ebay about 4 years ago with a high-draw stereo and don't really have any issues at all. I run typically about 13.5-14V nominal.

 

Any way to check the regulator?

Might as well replace the whole alternator?

 

You're voltage regulator and alt are fine. It's simple, with everything on (lights, AC, stereo, etc.) you are drawing out more amps than your alt can produce, so your voltage drops. Befor you go jumping into buying a high output alt you need to go ahead and upgrade your electrical/charging wiring. Use 4 gauge wire, and run new wire from the alt to the positive on the on the battery. Then use more wire and start that from the negitive on the battery and run that a new ground on the frame on the car. This may help/fix the problem, if it dosen't then you need to look into getting a HO alt. Either way it's a must to upgrade the wiring if you are getting a HO alt, but it may end up being a cheap fix as well.

 

Thanks for the help 94' Z28, I will do just that.

 

Yep no problem, let me know how it turns out. If you need to get a HO alt hit me up, I can suggest some places... will cost around $250 shipped for one (200 amps).

 

Could you PM me the links for the places you reccomend for the HO alternator?

Also, is it possible to buy pre-made 4 ga. alternator and battery cables? Or would I need to just get some 4 ga. wire and cut to length and crimp the appropriate terminals?