Dash Lights Brightness & Electrical Strain

[Ludigdrums]

It seems to me that at night when I first start my car, the dashboard lights all seem really nice and bright and everythings cool. However, it seems that it gets dimmer after a while. Giving it more gas doens't really seem to do anything, and I can swear that when I started it up that it was way brighter. I don't know if it's just my eyes getting used to it or other lights outside, but I really don't think so.

Also, it seems that every electronic component I use puts a rather significant strain on the system. If I look at the Voltage meter, I can see how much it fluctuates. Most drain can be noticed when using the rear defroster. The windows seem to take a bunch too. I thinking maybe the altenator is not the right amperage or something. As I've said in some of my other posts, I just got this car and it seems like there has been a lot of electrical issues/tinkering done. So, if I have a bunch of things on, the guage will almost go to the red. I also know that as motors (such as the windows) get older they require more juice, but shouldn't the altenator compensate for all the electrical loads and keep the voltage regulated?!

Thanks as always for your responses!

 

[silver 80]

turn everything on and check voltage @ battery while it's running. Is you battery in good shape?

 

[theo]

What alternator have you got? I have a similar problem with my 80 - I think the alt is either under powered or in need of a rebuild/replacement. There's a section on this forum somewhere in the tech center knowledgebase that will give you the correct alt part# for your year. Check to see if you have the right one. Although this is only relevent if an old one is still on there, and it hasn't been replaced. It should be 70 (or more) amps - as mine's the year before yours and mine should be 70 amps. The rear defogger is a bottomless pit of battery drainage!
Like silver80 says, check your battery voltage with everything on (voltmeter across bat terminals) and if you can, check it at idle and moderate speed, because the alt won't provide all its power until it's spun up a bit.
You might need a stronger alternator, or just to rebuild your old one. See if you can find out what current the present one "claims" to put out. If it's less than 70A, i'm fairly sure it should be gruntier.

 

[Ludigdrums]

OK...
12.6 @ Battery w/car off
14.6 @ Battery w/car on
11.2 @ Battery w/car on + all accessories on

The radio actually shut down while I used the power windows as everything else was on.

The altenator is a Delco-Remy and I cannot see what the AMPs claim to be. It also seems that the main connector is very close, if not already touching, the valve covers. I don't know if this is good or bad.

So, I don't know what these numbers should read, so any info as always is great! Thanks!

 

[theo]

Sounds just like my problem - The alternator is charging the battery fine when you don't ask too much of it, so you're seeing the 14.6 volts when the engine's running without any other major load.

The fact that the voltage drops so low when you load up the alternator means mainly that it can't produce enough current to keep the battery charged - so you are sapping the battery instead. If you think of the battery as a pressure vessel, and the current as a fluid flow into or out of the battery. You measure the voltage (pressure) of the battery just sitting and get 12.6V. Now when the engines running, the alt produces a current flow into the battery. If there's almost nowhere for the flow to go, the "pressure" builds up so you see 14.6 with the accessories off. The voltage regulator in the back of the alternator prevents this pressure from exceeding about 14.6V, so your battery doesn't
"burst", (to keep the pressure analogy going!)
No you turn everything on and open the flood gates - there's a big current flow out, to power everything, and the alternator can't provide enough flow to keep the pressure up. What's going out is more than whats going in, and the pressure will drop. Hence you read 11.2V, actually less than the resting battery. That 11.2 would continue to drop if you watched long enough. I'm sorry if thats' really insulting - it's the best way I know to describe it, and my car lectrics knowledge is pretty limited, so there'll be loads of people who think that was a bit of an over simplification!
Seems your alt needs to be tested for current output - what happens if you rev up a bit, does the voltage go over the resting figure?
Certainly make sure that connector is insulated from the valve cover, then have a place test your alternator. Might need a rebuild, or just a bigger capacity alt...
Let me know how you come out, cos I need to get mine sorted sometime before the winter....
Cheers!

 

[Ludigdrums]

I like the analogy theo, and no insults taken.

The revving doesn't do anything. I've actually had this while driving too, so I know that it doens't do anything for the voltage.

I'm not sure how I would keep the connector away from the Valve Cover because the altenator is in the correct position. How would I move it without affecting belt tension?

 

[theo]

I can only think of using a new belt - where is the alt in its travel? You should be able to tell if it should need a shorter or longer belt by looking at the current position
If the connector is on or near the cover, then it could well be the wrong length belt anyway...
If it's the live connector you're talking about (red, marked "bat") ,then i'd sort that out ASAP, cos it could cause a really nice light show one day!

If you're gonna get a new belt on, it's not much of a jump to take the whole alt off and get someone to bench test it for you. Like i say, it should be pushing out 70 or more amps - that's the standard ball park for that year, I think.

 

[Ludigdrums]

As far as the connector that I was talking about, it's the one with the 2 wires (red/black I think). I actually cleaned those contacts a bit with electrical cleaner, and I think it may have helped a little...but not really. And now it does seem that more revs helps out a bit. I still am under the impression that the altenator should be compensating.

Also, something I forgot to meantion was that the Tach seems to raise about 1/8th - 1/4 of an inch when the rear defroster is on. It also seems to tick with other electrical drains at times. Meaning it travels a short distance up and down. Don't know it this is normal or not.

 

[theo]

The connector you're talking about - is it like a two pin plastic thing? I can't work out how it's touching the rocker cover, since on mine, all the connections are on the left hand (driver side) of the alternator, and so well away from the rocker cover. What side is your alt mounted? I assume the driver's side? Any pictures?
I'm not sure about the tach issue, mine's never worked. Maybe someone else can offer some ideas on that...?

 

[Ludigdrums]

Here's pic of my altenator which is on the driver's side.

 

[Ludigdrums]

Here's another

 

[Ludigdrums]

And 1 more

 

[theo]

Hi Ludigdrums- I'm working late 2nite ( it's half 9 here in UK), so I've just looked at your pics - That's not quite what i expected...
It looks like your alt is upside down!
Don't panic, I may be wrong.....
I'm trying to think if i have a pic of a normal setup on my work PC
I can't vouch for after market alts, but the standard set-up would have that casing rotated 180 degrees.

Aha, I've just worked out what is wrong with it! the front part of the casing, ie the bit with the mounting bolts, is the right way around, but the back is 180 degs out. It comes apart in two seperate "shells", and either someone's put it back together wrong, or the whole thing is meant to be mounted on the other side of the engine. Perhaps this suggests it's the wrong one, since I think most or all later vettes should have the alt on the drivers side.

You can see those wires aren't comfortable like that, they're all pulled out too far from the fender.
Having said that, there's no reason why it shouldn't work, as it's still spinning the right way! So the case continues..!
Just watch those connectors on the rocker. A slightly longer belt may help to pull it back out of contact.
I'd be looking at having a good vehicle electrician test the current output of it. If it's not getting up to 70A with moderate engine speed, then rebuild or replace!
I'll see if i can find a pic of the "proper" orientation....

 

[silver 80]

someone has replaced that alt, and I would bet that they replaced it with the wrong alt. Theo is right the two pin connector should be in the center(top) or to the left side of the alt. If you need pics I'll post one of mine tomorrow.

 

[silver 80]

sorry if this is a little late.

 

[Yoda]

If the alternator fits into the mounting brackets, the pulley is correct and the current rating is right for your Corvette, then the connection configuration can be changed by taking the alternator apart and moving the back to match your application needs

This is refered to as changing the clock face of the alternator Ask at any of the parts houses around where you live. They should be familar with this, and probably have done it few times..

Good Luck
Bud

 

[DDLS3]

It is fairly easy to do as Bud said. Many alternators have instructions in box describing how to do it. The only trick is to retain the brushes so you can put the commutator back into place. This is done with a couple of paper clips inserted into the holes provided in the housing for that purpose.