Battery Light Issue

Does the new alternator come with an internal regulator?

If not, that component is the most likely culprit.

i dont know. i was on the road working and had to pay a mechanic to fix it. Cost me buco bucks for an easy job.. thanks

Check the belt tension on the alternator. Adjust to specs if needed. Don't go too tight, you'll burn up the bearings.

The belt is spot on. Replaced a few months ago. thanks

Drive it for a while or put a trickle charge on the battery. It's possible that the new battery lost some charge while sitting on the shelf.

Idle speed could be too low also.

Also make sure the pulley size on the new Alternator is the same size as the original.

If it is much bigger, the alternator revs will be low and therefore the alternator wont output the correct voltage or current ro properly charge the battery.

Regards,
Sapper

It sounds like a regulator problem now.

The faulty regulator might have been the reason the first battery/alternator failed? You said it failed on the road away from home? and a mechanic just replaced them and charged you extra. If it was a regulator integrated into the alternator, this is not it.

Next is the stuff you were sold

The new alternator with regulator regulates to a slightly lower voltage. That indicates that you might have been sold a reconditioned unit that was defective from the start. I am not sure about the innards of these things, they may have a bad internal ground leg, with a changed voltage drop to the reference. They may also have a 'cooked' reference that now dances to another voltage tune?

GA

That is also my take, either the old alternator was just cleaned and replaced (but charged for) or the replacement was already defective (a very common occurrence here at least with "repaired" alternators NOT from the original car manufacturer!!)

The OP should realise that its actually quite simple to make some simple tests with a voltmeter to mostly see if an alternator is working well. It probably won't find out exactly what is wrong as detailed in depth understanding of the functionality will be needed, but it will alert to most usual battery/alternator problems. Then to a car electrics shop, NOT A MECHANIC!!!

Connect a DVM across the battery set it to DC volts, place the meter so that the leads will not touch anything hot or moving. (Put the red lead on + and the black lead on -, or accept that all voltages will be displayed as - voltages....

Engine off, the battery will probably be somewhere between 12 and 13 volts on a car that is being normally used and everything is working as it should.

Start engine, battery voltage will still be low, but it should now show an increasing voltage as the alternator starts to charge, depending upon engine revs. Higher revs = faster charging. No need to race the engine as 2000 RPM is enough.....

Leave the engine running and the battery voltage should "top out" at about 14.4 volts (slight differences of max +0.15 to -0.3 volts between manufacturers). Depending upon revs and what loads are switched on (Lights, fan, heated window etc etc etc), this make either take 10 minutes or so or even not happen at all if load = max alternator output!! Which by the way explains how many people drain their batteries in winter with short journeys and "everything" switched on...

So its best to switch all loads off and let battery charge.

Turn on headlights full, the voltage should drop slightly, maybe to around 13.5 volts. Charging continues but at a lower rate.....

When the charge equals (does not charge anymore, note voltage, it should still be around 14.4 volts in a healthy car.....

If the voltage goes well above 14.4 volts, say 15 volts or more, the regulator is defective. It may be part of the alternator or seperate. It will damage the battery quite quickly, a half hour drive may possibly cause the battery to boil!!!!

After switching off, voltage will drop quite quickly over the next 10 minutes or so to less than 13 volts, especially if there are clocks or radios with memory installed....

If anything other happens than this, something is wrong......but do remember that this test is not perfect, but is a reasonable place to start as a cheap DVM is easily purchased and used.....

If everything seems to work as it should, but you still get problems, then a more sophisticated approach is needed with a visit to a car electrics shop with a load test on both the battery and the alternator......in my limited experience this is seldom needed as a problem will usually be seen when checking as I said.........

The mechanic was obviously useless as he did not check his work properly, or he pulled a fast one......

I hope it helps the OP further.....

GA

Have happy regulation !

This is common and easy to remedy. Clean the battery cables! Even if they look perfect, use a good wire brush. The film that developes between battery terminal and cable doesn't allow for good conduction. I have seen this dozens of times, especially on cables and batteries that look clean. The film is nearly invisible.

Clean the battery cables contact surfaces. Put some Vaselin on it, and carefully retighten. The insulating film is hair thin and glassy. Guess, how did I learn this? The hard way. After that a looong drive or a trickle charger to recondition the low battery. I trust, all other connections in the high current path are really clean and tight. Vaselin helps to keep them corrosion free too.

Another Cavalier problem. Good grief.

The regulator is working. 13.9V is pretty much right on the money. In this vintage the regulator is internal to the alternator.

I agree with Sapper in that it is turning too slow at idle and that the replacement alternator has a larger pulley.

This can be confirmed by gradually increasing the engine speed while constantly monitoring the voltage . There will be point where the voltage suddenly comes good.

Are you sure the new belt isn't slipping?

Not a cure but worth doing... By far, the simplest, and easiest, way to

spotless clean the battery wire terminals is... boiling water! Like Magic!

jt.

or, what do you call a camel with 3 humps........Humphrey! (ok, I'll take the pills..)

Does the light come on again even if the revs are kept high? If so it sounds to me like an intermittent fault in the voltage regulator, or perhaps loose regulator connection. 13.9 volts when it's working is OK. If it comes on and off with revs kept high it doesn't sound like pulley size.

Is it keeping the battery charged, enough to run the car normally?

Why not take it back to the mechanic who did the job? Maybe it's a faulty recon unit, or he may have just cleaned up your old one. If he refuses to do anything I'd check the connections and if they're OK replace the regulator, if you can get hold of one. They're not expensive. While you have it on the bench you can have a good look at it and decide whether it's a recon, from a breaker's yard, yours cleaned up or what, to "discuss" with the mechanic. I'd also check the brushes and replace them if any doubt.

If it's doing the same thing after 2-3 weeks of driving, and everything else seems fine, place a piece of electrical tape over the battery light on the dash.

Is the alternator has built-in regulator or an external regulator is in the vehicle.

See posts #1 and #3.

We don't know, and it appears we will not discover the answer.

Very unlikely to be a separate regulator on a '96 model, but it would good to have it confirmed.

Google search for voltage regulator 1996 chevy cavalier.

O'Reilly Auto Parts believes it is a separate item.

But what do I know? I'm just a dumb blonde Doorman.

That looks like a built-in regulator to me. An external one would have push-on connectors and probably a mounting bracket or eye.

It's a Cavalier, do not expect this Auto to ever be trouble free. The Cavalier is the #1 most talked about car on this site, as it was built using toothpicks and duct tape. I recommend pointing the car to either a cliff or lake, place a brick on the gas pedal with the car running, and shift into gear... Problem solved!

Collect insurance $$ and buy a Jeep.

_{I do not endorse insurance fraud.}

You omitted an important step.

Try to get out of the car before it hurls into the abyss.

Come on rotosplit, several posters have tried to help, some clarification/feedback would be welcome

Sorry i was away on work. Weii i buckled and took it a electronics shop. Bad regulator. there was a warranty on the alternator and the new install was covered. Thank you all for your support. Mike

Thanks for the feedback. Good to hear it's sorted. Interesting that new/recon unit was faulty from the word go. Sounds like it wasn't tested too thoroughly.

You are SSSSOOOOO RIGHT!

Many mechanics are totally out of their depth with testing alternators, none of them could set up an old DC Dynamo nowadays if required..!!!

All most mechanics today can do is replace a part.......if you find a good mechanic, keep him!!!

That is one of the reasons I used to do most of the work myself (and not just on cars either!), it was still cheaper than a mechanic even when I occasionally ruined a part though ignorance.....

For example, I have totally learnt the internal programming of my Kalor pellets burner and I have managed to reduce the pellets usage by half on the lowest power setting, which is the one we use 99% of the time......I don't know how many KWs that is, but I suspect about 1.5, instead of 2.5.....

I generally need about a metric Ton for a complete winter, October to April....a big plastic bucket of about 11 Kg. burns for more than 24 hours continuously. I used to need double that amount!!

DC Dynamo and 2-point and 3-point regulators were not that simple at that time even.

Only a very intelligent Auto-electricians were conversant to do it.

I was adjusting them before I was 15 years old.....using 3 meters at the same time if I remember correctly....it was not THAT difficult.

I had a quick look around on the web and I found very little about this, a lost art....

What exactly did you do to your heater to make it that much more effecient?

I am planning on retiring to a colder climate after have lived and worked in tropics for 40 years!

http://www.alternatorparts.com/7130_7140.htm