CoryMiller

So my car has been having some charging issues. Back in June, I replaced my battery and alternator (my battery had had enough of this Arizona heat). And everything had been working and running fine. Until I threw a CEL a month or so ago and my knock sensors went out on me. Replaced those, anf finally got it fixed. I don't know if the timing was just a coincidence (probably), but my charging issues returned. I drove around town yesterday, sat in a little bit of traffic, and stopped at the store near my apartment. I came back outside and my battery was dead. Nothing. Just clicking. So I get a jump, take it to Autozone. They said my batt was fine and so was my alternator. But on their little machine, it said that my voltage regulator had failed.

So after searching, I hadn't found a concrete answer, so where is the voltage regulator? Can it be replaced? How difficult? I figured something like that would be built into the alternator itself.

Fritz330

I believe the regulator is built into the alternator. Haven't seen one that wasn't in ages.

CoryMiller

I believe you are right Fritz. Doing some more reading around the web, I found they do sell the regulator by itself, but it's almost as much as buying an entire alternator from Autozone.

Further, I went to see what voltage my alternator was putting out at idle, it was pushing 12.15 volts with the AC on and 12.47 with the AC off. I've read a working alternator will push anywhere from 13.5 to 14.5, does that sound right? So it would appear that when I got a new alternator 3 months ago, it was faulty.

Fritz330

Yep, that would be my guess. It does happen, especially with rebuilt alternators.

CoryMiller

So I changed my alternator yesterday. Everything went swimmingly with the exception that it was 105 outside. Anyway, I changed the alternator, and tested the voltage. It was pushing out 13.9 at idle without AC and 13.3 with the AC on. So I was like, sweet, I fixed my issue. WRONG. Getting read to go out tonight, I am sitting in my car, at idle with the AC on waiting on my friend to come out to my car. Well there is a car parked in front of me and I notice my lights on its back bumper got brighter when I revved the engine. Then my radio goes out and th batt light pops on, so I give it more gas. I take it on a nice little drive on the freeway to try and charge the battery back up and take it back to my apartment. Pop the hood to test the voltage and it's pushing 12.47 volts at idle with no AC.

I am literally at a loss for words because I have no idea what this could be. It's a brand new alternator that I just changed out. Does anyone have an idea for what this may be?

CoryMiller

Buehler? Buehler?

This car will be the end of me. I go out this morning and start to tinker. I check the voltage of the battery with the car off, it's at about 12.35 volts, lower than it should. Should be around 12.5 I believe. Anyway, I crank it up and check the voltage. It's pushing out 14+ volts at the battery. It didn't even push that out when I started up the car right after changing the alternator. Anyway, I check it at the alternator, and it's always pushing about .3 more volts than at the positive battery cable. I am losing .3-.35 volts from the alternator to the pos batt. post. Is this normal to lose voltage?

Also, my dad told me to check out the big 100A alt fuse that is right by the battery. Does anyone have a DIY on how to remove this? I know that it is bolted in and doesn't just click in like smaller fuses. Please, any help is greatly appreciated.

ES300NZ

check the earth cable / replace the engines earth (double it up). I bet that's the casual issue,

you check the 100 amp fuse form the top, see if the link it broken there is a clear plastic window. It wont be. You car is charging. It is the charging unit which keeps failing.

an alternator will put out about 13.5 - 14.5 volts (at max), when charging at no load (no ac).
if an alternator put out between 12.5-12.8 volts, then I would call that 'partial charging/half charging'.

CoryMiller

can u explain what this is? also, worth noting, that the voltage output decreases over time of the car running. for instance, it started at 14+ this AM, ran the car for 10+ mins and before shutting off, it was around 13.8 volts.

Kapetand

Corey, did you ever get to the bottom of the issue? My son's 2000 es has the same problem. In 2 months we have gone through 4 alternators and 3 batteries. We even took to a stereo place to check wiring and then a me hanic who both found nothing. We are wondering who out is an electrical car wizard that can help us diagnose the issue

wmj259

There's been a lot of comments saying that the OEM alternator does not have enough overhead cushion in capacity. A common modification would be to use an alternator from a highlander (which is what I had to do. I've also gone through 3-4 alternators and haven't had any issue since).

If this is a battery drainage issue, you should measure the drain at the battery and start pulling fuses.