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Alternator/Regulator?

jstkrsn

Well-known member
Joined
Jun 3, 2002
Messages
59
Location
Parrish, FL, USA
Corvette
1992 LT1 White Conv.
My battery keeps running down. I can charge it right back up with my charger, so I think it is OK. After I charge it up and begin driving my gauge says 13-13.5 volts. It starts decreasing from there. Down, Down slowing as I hit the brakes, turn on the air with the fan, radio etc., to near 10 volts. If I turn the head lights on they are steady and bright. I believe they are connected directly to the alternator, not thru the regulator. So I think the alternator is OK. That leaves the regulator, which I think is bad, and just not charging the battery. I think the battery slowly runs down as it is running all the lights and accessories(except the headlights). It gets worse as the engine gets hotter. Anyone have any thoughts on this. I hate to replace tha alternator if it is only the regulator.
 
E

Eagle85C4

Guest
I think you might not understand how it works...the alternator produces ac voltage. The regulator , as well as regulating the voltage also rectifies it, meaning it changes it from ac to dc volts.
The one big post out of the alternator is where you get the dc from...it goes directly to the battery.
It would appear you have a failing or failed alternator. You can take it to most auto parts stores and they will check it for free, while it is still in the car. Then you can decide what to do with it.
For my 85 it requires a 120 amp...I went to GM and almost lost my lunch when they said upwards of 300.00, so I went to NAPA and got a 120 amp from them for a "c note", with lifetime warranty. It pays to shop around....
 

Ken

Gone but not forgotten
Joined
Jan 30, 2001
Messages
8,236
Location
Hermosa Beach, CA
Corvette
1987 Z51 Silver Coupe
Sounds to me like the battery itself is dying. When that happens symptoms similar to what you describe are possible.

_ken :w
 

vigman

Motor head!!!!
Joined
Feb 13, 2001
Messages
3,471
Location
Valencia, CA,USA
Corvette
88 Convert ( SOLD ) /1973 coupe 4 speed/1964 Vert!
My Vote

Alternator.....

Tis Dead

Vig!
 

jstkrsn

Well-known member
Joined
Jun 3, 2002
Messages
59
Location
Parrish, FL, USA
Corvette
1992 LT1 White Conv.
If the alternator is dead, why are the headlights, even on high beam steady and bright. That's what confuses me.
 

vigman

Motor head!!!!
Joined
Feb 13, 2001
Messages
3,471
Location
Valencia, CA,USA
Corvette
88 Convert ( SOLD ) /1973 coupe 4 speed/1964 Vert!
Because

I'm betting the diode bridge is toast!

So instead of GOOD DC current getting to the batt it has an AC component on top.


HAve it checked out!


Vig!
 
S

Shadowing1985v

Guest
Eagle??

i have a 85 man

and my wires off my alt goes to my starter

then to the battery

not directly

anyways,, my battery was loosing juice and i just notice why it was draining yesterday

my hood lite was staying on,,


i had that bat fully charged and that hood lite drained it dry in 2 days, im not sure your 92 or what ever model u had ,, has a mercury switch,, now im currently looking for 2 new mercury switches,, anyone know??


the alt is real easy to take off, I recommend to just take it off,, , 4 easy bolts,, and take it to a auto store and have them test it out

i put a 80 amp alt on my 85 i think,, i can't remember the guy at the store said it calls for a 120 am or a 80 am for an 85 vett

my car is loaded with everything,, i wonder i fi have enough or not

anyways,, see if your local auto place can check if your bat is good or not,, they test it by puting a load on the battery

this will keep u from spending alot of money

but then again if your alt is producing 13 something volts id block it out, i bet you have a lite on or something
 
S

Shadowing1985v

Guest
my car runs at 12 volts sitting still

and 13 something while moving
is that what your guy's does?

or this a sign of my alt not being big enough
 

vigman

Motor head!!!!
Joined
Feb 13, 2001
Messages
3,471
Location
Valencia, CA,USA
Corvette
88 Convert ( SOLD ) /1973 coupe 4 speed/1964 Vert!
Oh yes

The regulator is built into the rear of the alternator... not a seperate piece.


Vig!
 

vigman

Motor head!!!!
Joined
Feb 13, 2001
Messages
3,471
Location
Valencia, CA,USA
Corvette
88 Convert ( SOLD ) /1973 coupe 4 speed/1964 Vert!
And reguarding the dash voltmeter

It reads DC only......

It would be a good test if you had access to a GOOD voltmeter..... and confirmed these suggestions... but I will bet even money that you will have a minimum of 6 volts of AC sitting on top of the 9 or so of DC.

That's why the gauge reads what it does, but the lights stay bright... I'l bet if you look at em directly with the car idleing... they will flicker a tiny bit.....


Vig!
 
S

Shadowing1985v

Guest
yeah thats true

the dash wil read like .5 off or so

usually

take a volt metter and touch positive to negitive
 

vigman

Motor head!!!!
Joined
Feb 13, 2001
Messages
3,471
Location
Valencia, CA,USA
Corvette
88 Convert ( SOLD ) /1973 coupe 4 speed/1964 Vert!
And the winner was.........

Curious on this one.


Vig!
 
M

Markuk

Guest
Surely there must be a good auto electrician in your area that can repair your alternator as Vigman says it is normally the bridge that goes and this is just made up of 4 diodes, I don’t think I have ever had one burn out the windings. In the UK we will always try and repair our starters and alternators usually costs no more than $30/$50. English philosophy= Fix it bodge it beg one nick one do anything but buy a new one..
 

vigman

Motor head!!!!
Joined
Feb 13, 2001
Messages
3,471
Location
Valencia, CA,USA
Corvette
88 Convert ( SOLD ) /1973 coupe 4 speed/1964 Vert!
Funny stuff

Well the yanks have a spin on this.....

JUST BUY A DAMN NEW ONE...IT'S gonna break anyway.!


Smeggin PEP BOYS!

Vig!
 

jstkrsn

Well-known member
Joined
Jun 3, 2002
Messages
59
Location
Parrish, FL, USA
Corvette
1992 LT1 White Conv.
Well I haven't replaced anything yet. The battery went down completely yesterday on the way home from work. I charged it for 6 hours this morning with a 10 amp charger to 13.5 volts. And it seems OK for the moment. We'll see.
 

vigman

Motor head!!!!
Joined
Feb 13, 2001
Messages
3,471
Location
Valencia, CA,USA
Corvette
88 Convert ( SOLD ) /1973 coupe 4 speed/1964 Vert!
Jim

From one CA bro ( Dude ) to another ( like kool ya know)

Trust me on this.....

It could be 1 of 2 things...

1)The Alt is toast ( is it the orig one?) and If so how many miles on your ride ...(.dude?)

( My moneys still on the bad ALT)

Do you have a good meter?

2) Fusible link C is the junction point between the ALT output & the battery..

That's the ONLY large current path available. The lines do not split off and go to other area's until you get past the fusible link.


Link "C" is located at the left firewall
( drivers side ) under the hood...behind the battery..

There is a square black plastic junction area for a GOB of red wires.

If you go further... disconnect the battery & remove it

If you want to ohm it
* the red wire going to the Alt output * out... you will have to remove the nut holding all the wires down...

Remove the nut & all the wires & seperate em.

Remove the nut off the back of the ALT.

remove wire.

Get out OHM meter and hook one end to the ALT red wire and go fishing for the other end at the junction area.

Fun huh?

Oh and Mark... sure you can have all my old parts... your paying shipping ....right?


Vig!
 

vigman

Motor head!!!!
Joined
Feb 13, 2001
Messages
3,471
Location
Valencia, CA,USA
Corvette
88 Convert ( SOLD ) /1973 coupe 4 speed/1964 Vert!
Oh yes

Jim.... whe the key is ON ( engine off ) the BATT light comes on....correct?

And after you start.. it goes off... right?


What about @ night... car running lights off...idle.. does it glow dimly, and when you rev it ..it goes away?


Vig!
 

jstkrsn

Well-known member
Joined
Jun 3, 2002
Messages
59
Location
Parrish, FL, USA
Corvette
1992 LT1 White Conv.
Vig, Battery light has never come that I noticed, I've been monitoring the digital voltage. When I turn on the lights it doesn't change, when I hit high beams it doesn't change. If I hit the brake lights, or turn the ac fan up on high, that's when the voltage starts to drop. All the accessories sucking all the juice out of the battery. If I never use the brakes, turn on the radio etc. I seem to be fine. So I am confused as to whether the battery is weak (though it charges up on my little charger) or the alternator is not charging the battery (but the lights are nice and bright, even high beams). One minute I think it's the alternator, and the next I think it is the battery. I'm thinking to just start replacing thinkg till the problem goes away. I have a craftsman setup somewhere in my garage I used many years ago to check such things, but it and the book are buried in a corner somewhere.

Jim
 
M

Markuk

Guest
Its probably worth it to me, to give you a idea why we fix it, you may have seen my post on rocker panels, I looked at buying new ones, I can buy them in England no problem, BUT $600 a 20' container will cost$1200 that’s a lot of parts.Hey this could be a good earner. As I said we love second-hand bits after all the whole cars are anything up to 50 years old so why not use a bit that’s only a few years old and maybe keep it original too. Seriously if you have anything I can re-use it would be worth the shipping.
 

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