Voltage Regulator or Alternator?

[kronus]

The other night my battery light came on at the same time a loud squealing started in my engine bay. Easy to diagnose, so I checked the alternator. It looked like the belt had loosened up, so I retensioned the alternator belt and voila, the battery light went off.

Out of curiousity while I was driving the car I hooked up my Bluetooth adapter to check the voltage, and it was jumping all over the place, both at idle and while cruising. Lowest reading I had was 11.2v and the highest was 15.9v. Can't be a good thing.

As I drove the car home, I noticed the car would miss right around the 2k rpm mark and my headlights would dim at about the same time. When I pulled into the driveway and turned the car off the headlights got very bright and then everything went dead. No power to the interior lights, headlights, windows, radio, starter, nothing.

So I figured that while my alternator belt had been loose, the battery had been drained to the point where nothing had power. But having experienced a draining/ed battery before, I know it's not a sudden power loss, but a gradual one (lights dimming before going out, etc.) So this makes me wonder if this is the voltage regulator going out rather than my alternator.

Also, after coming back to the car an hour or so later, it looks like there is a very tiny charge coming from the battery. The interior lights come on when I open the door, though they're very faint.

I don't mind buying an alternator, it's about time, but I don't want to buy one if my voltage reg. is going to kill it soon after. Do these symptoms sound like the alternator, or the voltage reg?

 

[dsmcurse]

Voltage regulator is internal built to the alt. Its not a extra external piece. If your regulator goes tits up then your alt is dead and need replaced

 

[GSLENK]

any parts store can check your alternator or battery or both. the battery test is just as accurate in and out of car, the alternator test could be done in or out of car.

Voltage regulators are "inside" (sometime inside, sometimes bolted into the outside) the alternator, so if you buy a new alt, you have a new reg. im 99% sure.

Voltage regulator is internal built to the alt. Its not a extra external piece. If your regulator goes tits up then your alt is dead and need replaced

Well you can replace the regulator ($40-$60 iirc), but it may or may not be worth it. find a good deal on a good alternator with a good warranty and be done with it.

Alternators wear out just like their voltage regulators... I would say if one goes out, the other is probably not too far behind.

 

[kronus]

Well what complicates this is that the 420a platforms uses an external regulator, but the regulator is INSIDE the ECU. So, therein lies the problem. New alt. has been ordered, but it doesn't really sound like the symptoms of a dying alternator.

 

[dsmcurse]

What? Are you for reals? Well, I've never owned anything but GSX models I've never had a Eclipse "go slow". (Kidding of course). I have never heard of 420A platforms having a voltage regulator at the ECU and not in the ALT...? Weired.

 

[stars]

Well what complicates this is that the 420a platforms uses an external regulator, but the regulator is INSIDE the ECU. So, therein lies the problem. New alt. has been ordered, but it doesn't really sound like the symptoms of a dying alternator.

Make sure you fully charge that battery before you install the "new" alternator; that is the most important step first, even if the battery is "brand new" still; put it under a charge @ 40 AMPs for 60-90 minutes. If it is mostly charged then do 10 AMP charge for 120 minutes. If it is a Wal-Mart purchased battery, throw it out and go buy an Interstate or Exide battery. I don't know where you got that information that the "voltage regulator" was not internal within the alternator? If I may point out that on the back of your alternator you have a "plug in" style connector; that is where your voltage regulator is housed.

Keep in mind this about a battery. If a battery starts to internally short out then the Voltage Regulator senses the extra demand of current going to the internally shorted battery (voltage drop), the Voltage Reg. starts to allow the Stator field inside the Alt to produce even more current to flow to the battery (you see the max output jump to 15.9 volts). Soon as electrical demand is satisfied your Voltage reg. cuts off and you got a reading of 11.2 volts; which is where you should have spotted your problem i.m.o.

If the alternator is not putting out a Minimum of 12.6 volts then your battery is not getting charged, period..............A battery has 6 cells inside. Each cell holds 2.1 volts per cell. 6 cells x 2.1 volts per cell Equals 12.6 volts. Alternator needs to output a minimum voltage of 12.6 volts just to keep the battery charged.

 

[dsmspickdad]

I am sure almost positive that there is an internal voltage regulator. So replace the alternator because your alternator (regulator) is bad. If you have questions call me. I just look at the 95 Esi in driveway and the alternator does have regulator inside of the alternator, just behind the cooling fins on the alternator.

 

[kronus]

Ah ha, I found the confusion. Yes the regulator is internal to the alternator, but the ECU controls the field switching. So, from what I've gathered from this little thread is that this is most likely a dead alt. I've got a brand new one ordered in, so we'll see what tomorrow brings!

 

[LeeSD1]

The Voltage regulator is NOT in the alternator on the 420a its in the ECU. You can use an external voltage regulator, the one symtechlabs sells for the 420a eclipse. I think the best way to go is with a 1 wire self-exciting alternator as the voltage regulator is built into the alt. itself.

 

[LegionGS]

Ah ha, I found the confusion. Yes the regulator is internal to the alternator, but the ECU controls the field switching. So, from what I've gathered from this little thread is that this is most likely a dead alt. I've got a brand new one ordered in, so we'll see what tomorrow brings!

So what happened man? It was the alternator that went bad? I'm having a problem like yours but tomorrow I'm going to take out the alternator and check it on a auto part's store first... I hope my alternator went bad.

 

[fiveeauxfo13]

Whoever thinks a 2g 420a dsm has an external voltage regulator, needs a new way to start recieving inteligent intel about there inteligence??? Does that sound rite? Thank you, now please start rerearching the correct info, before posting false advice!!!

 

[VelocitàPaola]

Whoever thinks a 2g 420a dsm has an external voltage regulator, needs a new way to start recieving inteligent intel about there inteligence??? Does that sound rite? Thank you, now please start rerearching the correct info, before posting false advice!!!

It sounds like they just got their terminology wrong. The regulator is internal to the PCM (i.e. it's not a stand-alone unit), but external to the alternator. In other car circles, an internal regulator means inside the alternator, and an external regulator means a stand-alone unit outside the alternator.