Hey everyone. I just installed a new alternator in the spring and a new belt, tensioner and idler pulley this week and lately I have been having a situation where I had dim lights and only about 12v(1/3 of the way between the 2nd thick notch and 14v) on the voltmeter with the engine at idle (and in gear) when I have the headlights, fog lights (factory and aftermarket), heated seat, heater/fan, radio, radar detector, GPS, LED lights on. It seems to go back to 14 if I turn off the fog lights and heater fan in most cases or if I rev the engine a bit. I have not seen it go this low before and the battery light is off. With everything off, it usually rises slowly to 14 on startup and hovers there at idle. Does this mean I have a bad alternator?

 

Hey! It sure seems to point at the voltage regulator(built in to the alternator) and while you do have aftermarket goodies on your unit the stock alternator should be able to keep up with the load-stock being what? I don't recall-125amps or so? When I replaced an alternator in one of my units I opted to go with NEW instead of remanufactured($125 @NAPA) It has now been in two units and still performs perfect! There are also MANY aftermarket high-amp alternators availiable,but:high amp=high price! Consider upgrading but first test the whole system! Good luck!

 

Actually that sounds pretty normal. When you are idling, the alternator isn't spinning as fast so the output goes down a bit, especially when you have a lot of electrical running (such as aftermarket accessories). Is it hitting the red marks on the gauge?

 

I'm keeping an eye on this thread, since I have the same condition. Though it happens even with just the headlights on, not all the other accesories that Computernerd is using. My alternator was replaced about five years ago, not sure of their lifespan.

 

I believe the stock-factory alternator is 105 amps. Sufficient to keep up with the stock items installed on the vehicle but probably struggles a bit with aftermarket accessories.

A couple of other notes on your description; these alternators are temp compensated. Meaning, that when cold (starting n the morning for example) it tends to charge higher to replenish the battery after sitting and then starting the car. After charging the battery and the alternator getting warmer, it will drop back down to the normal 13-14 v charge range.

My 98 will generally charge lower at IDLE with many accessories on, especially the rear window defroster. As long as it doesn't drop into the red tick marks on the volt gauge you should be A-OK. If it was truly a charging/alternator issue your vehicle would stall and die because you also need a minimum amount of voltage to keep the fuel pump, ignition, computer etc.... running.

 

I may look into a high output alternator. This problem is BEFORE I plug in the computer system or other stuff, but the car still runs fine. The rear defroster alone is enough to cause this without anything else on. It isn't hitting red marks, but the voltage is low enough for it to be the same voltage as with the engine off. No battery light.
The cold temperature thing fits my alternator also. I notice almost 15v on a cold start in the morning. Sometimes the engine and fuel pump sound different with all the accessories on.

 

Did you check the actual voltage or are you just going off of the gauge? My gauge read quite low but when it was reading about 12 on the dash the scanner was showing 13.5 and so was the multimeter.

 

Off the gauge. I'll check with a multimeter.

 

I've seen several versions of our alternator on ebay in various high output...120, 160 amps. They do cost a bit more but might be nice to have that extra output headroom.

Please keep us updated on what you do and if you get a hi-output, how well it works for you.
Thanks

 

I think I will get a high output eventually, but I have alot of other stuff to get done first (tuneup/door striker repair/brake hoses). But I did think of a simpler solution to try first: What about the wiring between the alternator and the battery? I tried adding a 4 gauge wire when I put in the new alternator, but it will not fit the battery terminal. How could I add another 4gauge wire that will fit the side terminal on the battery? I have the OEM battery cables and they are in good condition.