tonight, while parking my car in the garage, i noticed that above 1k RPM, there is a very slight flickering in my high beams and gauge cluster lights. that leads me to assume that all fillament bulbs in the car are having the issue. my LED lights and HIDs do not have the problem. i believe i have the original alternator (so 44k miles, 9 years), but until yesterday, i also had the original battery. the new one is a duralast gold. a battery that bad can definitely cause severe wear on the alternator. but that doesnt explain why the lights only flicker above idle. anybody got any ideas? if i dont figure anything out, ill probably take the alternator out and take it to autozone to get it tested, but since power output is fine, just wobbly, it might pass anyway. also, at the time i noticed that flickering, i had lots of lights on (35W HID fog and low beams, as well as 55W high beams) the radio was on, and the blower motor was on the low setting. could the relatively high load be the cause?

 

You just replaced your battery? Did a Autozoner do it? Make sure your battery connections are tight. And for future reference, I used to work at Autozone and I am pretty sure that Duralast batteries (even the gold) are engineered to fail just past the warranty period...you would be amazed at the turnover rate on those things.

 

nope, replaced it myself. and even with the old one, voltage would randomly drop during driving. not sure if that still happens or not. it was very rare. and the warranty is 8 years, with 3 yr free replacement. if it only lasts that long, ill be happy

 

I also worked at Autozone, and don't recall very many Duralast batteries coming back. I just replaced a Duralast in my car that was almost 10 years old. Sure, there will be some, just as there will be for other brands. Consumer Reports always has the Duralast rated #1 or #2 in the classes they test. They have a sophisticated set up for the tests, including a cold room and hot room. Temps range from -40 to + 120.

 

well, it wouldnt really make sense for it to be the battery, would it? unless the vibration of the engine above idle is somehow causing it to short internally a bit. but i doubt thats the case. thinking back, i *think* this was happening with the old battery too. i think i remember the gauge lights flickering a tad, but i never noticed the headlights. mostly because they are rarely shining on a wall while im sitting still and giving the engine a rev, lol.

 

If this were me I would begin by checking the grounds. Start in the engine bay and work your way back, there are many of them. After that I would begin checking connections as it could be a loose connection at the alternator, a damaged connection at the cluster itself(although you said your head lamps were also flickering so I doubt that is where you will find the problem). Never the less, a loose connection in one of those circuits could be the culprit. I would try to see if both circuits share a common ground, if so than there you go. I hope I have been some sort of help here.

 

ok, ill do that when i get some free time. thanks a lot!

 

ive been doing some digging, and some people have had similar problems from a bad voltage regulator on the alternator. suggestions seem to be to unplug the connection to the alternator (i assume the plug thing), while the problem is occurring. wouldnt this cause voltage to spike, and possibly cause damage to electrical components?

 

Well there could be a few things going on. Grounds like mentioned above are a possability.

The next possability is that the rectifier bridge in the alternator is weakened and going bad. If you have access to a MicroVat or any other higher end alternator tester you will see the condition of the rectifier in the AC ripple output. What that means is the diode bridge which converts the AC to a DC output is allowing AC to leak past it. Cheaper testers might not detect this since all they test is voltage and amperage output.

You can try an analog Meter on the output post of the Alternator to see if the voltage is spiking. An Occiliscope would also work well but not too many people have one laying around...

Another option is to just try another alternator.

If you ignore this and one of these two problems are the cause.....it will get worse and you will do damage to sensitive electronics.

I would not recommend unplugging the Regulator wiring to the Alternator. Unconnected it wont hurt anything. However the process of unplugging the connector while the engine is running is dangerous because its not a simple on or off connection. While you wiggle the plug out you are making and breaking connection and that can cause spikes. Long story short that plug powers the armature of the Alt and the regulator. When voltage drops below 12v the regulator switches on and output is through the positive battery post and ground of the case. Poor connection while you wiggling and removing that plug will be "seen" as low voltage due to resistance.


Terry

 

the voltage ripples dont show up on the analog voltmeter i have. however, so far ive seen this ripple in the headlights, gauge lights, done lights, radio lights, cigarette lighter, and basically every bulb in the car. that leads me to believe that the problem is not a specific circuit. ive recently cleaned 4 of the grounds on the front of the car, and im assuming at least one of those should be able to do the its job well enough to keep all the circuits from fluctuating. theres also the fact that the problem doesnt occur because of engine vibration, but because of speed. where could i get the rectifier tested? the only place around that i know of is autozone, and im willing to bet they have a cheap tester

 

I dont think you can replace internal alternate components. Did youchek voltage at battery with car off? should read about 13.0 to 13.2vdc. then start it up, and check again. you should see an increase to 13.8 to 14vdc. indicating alternater output. That being said if its internal you'll have to replace it anyway.
I would do an output test, if thats ok you might want to get it tested off car.
Good luck

 

How do you think an alternator gets rebuilt? Once upon a time we didnt have the luxery of going out and buying a complete alternator. I can get you any part in that alternator you want. You more than welcome to stop by if your ever in the Plainfield area and I will show you how testing and rebuilds are done.

Grounds are not as simple as this ground works here and this ground works there. One bad ground can cause an entire slew of problems. I have seen it car after car. If you dont like my advice then I am sorry, i have told you what direction your problem is. Throw an alternator at it, its likely your problem. I will keep future diagnostic advice to myself. Good luck to you.

 

voltage with engine on and off seem fine.

and tggodfrey, i didnt say im not going to check the grounds. i just thought those were usually responsible for more isolated problems, not system-wide fluctuations in voltage.

 

You can buy alternator rebuild kits on fleaBay. They are a lot cheaper than a replacement alternator and you can find youtube videos explaining the entire process. It is not that difficult (but there are a couple of tricks the videos point out) and I would recommend getting a kit that replaces everything, including the bearings.
IIRC you have a CS144, 140 amp alternator.
http://cgi.ebay.com/ebaymotors/ALTER...item5d30091a83

 

well, thats not cheap, but it is cheaper than a new alternator. id like to make sure it is indeed a problem before throwing $$ at it. money's a bit tight right now