Black13B

iTrader: (1)

so as some of you know (especially after the ottawa meet ) ive been having some voltage issues..

first i thought the gauge was just reading wrong.. and.. well it is but its not far off at all..

upon return of ottawa i realized i had alot of testing to do both with my cooling system, oil pressure system, and voltage system (as my gauges dont seem to be putting out accurate readings)

tonight: i rigged up an "autometer phantom" volt gauge out of my brother's stereo-competition sunbird (long since met it's fate ) and the gauge i know reads properly (picky people in those stereo competitions)

ANYWAYS i rigged up a momentary switch to it, and did a quick run through the door and went for a drive (at night which is when my voltage problem seems to occur)

heres the results

(start means "begin test" etc etc btw the brake part of the test was to add the brakelights to the electrical load)

start (0 sec) - idle, no loads - ~14v
end (60 sec) - idle, no loads - ~14v
start (0 sec) - idle, park lights - 13.9v
end (45 sec) - idle, park lights - 13.6v
start (0 sec) - idle, all lights - 13.8v
end (45 sec) - idle, all lights - 13.4v
start (0 sec) - 3rd @ 3krpm, all lights - 13.9v
end (30 sec) - 3rd @ 3krpm, all lights - 13.6~7v
start (0 sec) - 3rd @ 3krpm, no loads - ~14v
end (30 sec) - 3rd @ 3krpm, no loads - ~14v
start (0 sec) - idle, all lights + brakes - 13.8v
end (15 sec) - idle, all lights + brakes - 12.4v

everything in bold is a result that showed voltage dropping, or just something i want you to pay attention to.

it has:

new 115 amp alternator
"new" battery - tested ok with battery tester, i got it for free via work, but sad to say i cannot physically prove it has a solid working backround before i got it
new grounds to the chassis, alt bracket, and motor.

now remember, before it was doing the same thing with my old battery and old alternator

new alternator improved idle greatly, but still - those are my results

sorry for the length of this post

what do you guys think? i would imagine some sort of short in the lights somewhere, or the battery cant hold a charge or something..

anyways, any input is greatly appreciated

Black13B

iTrader: (1)

oh yes and btw:

idling with the parking lights on.. if the idle drops say 50 - 100 rpm (when it gets rough)

my voltage is dropping by up to 0.6v.. it would seem that my idling is directly related to my voltage

btw: testing battery car off before all tests showed 12.6v

testing battery after tests car off showed 12.7v

but before i shut it off i let it idle with no loads, so it brought back the surface charge just so you guys can keep it in mind..

thanks again!

Icemark

That is not a new alt... a new 115 amp alt would have 14.5 at idle without any issues. The only other reason would be extreamly bad grounds (not just bad grounds, but extreamly bad grounds).

BTW, anything under 12.6 volts the alt is not working at all. It is strickly discharging the battery at 12.6 and under.

Black13B

iTrader: (1)

ill take the alternator back to the place i got it and have it inspected.. (1 year warranty)

while im doing that: anyone else have any comments?

SureShot

Maybe with the engine running and some load (lights & fan), use a DVM the check voltage at the battery and at the alternator output.
If they are not exactly the same, your primary alternator wire may be weak..

Black13B

iTrader: (1)

good call man.. ill look into that this morning.. let you guys know if i find anything..

Relisys190

iTrader: (4)

I am having similar problems, and i am pretty sure my primary wire coming from the Altenator may have a short in it.

I have replaced all the negitive (ground) wires that i could find. But if were to go about replaceing the MAIN charging wire how would i do so?

Where does the Positive from the battery go? Where does the Primary wire from the Altenator go? Ect.ect...

Thanks-Markus

Black13B

iTrader: (1)

i was considering disconnecting the current "primary alt" wire and making a new one going from the + term at the battery to the alternator output terminal

just so see if it makes a difference..

BUT im unsure where the primary wire goes.. and BOY is that wire ever small.. does that have anything to do with it?

Relisys190

iTrader: (4)

I asked in a previous post if it would be "SAFE" to run a wire from the altenator output directly do the positive battery. I never got an answer... I TOO would like to run a 4guage wire from the Altenator output to the postive on the battery. but would it be "SAFE"

Also, it would be great if someone explained where the wire goes to from the altenator output.. also, where does the POS wire go to when it leaves the battery? this would AID in rewiring the positive side of the charging system. my negitive side i'm sure is great (6 new grounds total)

-Markus

Black13B

iTrader: (1)

ill look into it some more at work..

ill post if its safe.. im sure it IS, but i prefer to double check..

Icemark

The alt wire runs to the 80 amp main fuse in the underhood fuse box. It also "T"s off to a couple of spots on the way like the ignition switch, the heater circuit breaker and the rear defrost circuit breaker.

It should be fine to jumper or run an additional wire between the alt output and the input side of the 80 amp fuse in the underhood fuse box, but it would be a pain to remove the old wire and run a new one.

SureShot

In the link below in my sig (86-94 manuals), navagate to:
05_Engine_Electrical_System.pdf
Look on page G-6.
I see a direct wire from the "B" post on the alternator to the battery +, without even a fuseable link.

Icemark

G6 had the diagram for the alt itself... not of the electrical.

My info was based off of the S4 88 manual (since Black 13B has an 86 not a S5 [as your post suggests we look at]) and page 50-14 and 50-15 since that is the electrical schematics for the S4 coupes.

SureShot

OK Mark - I'm busted - going for the short answer.
Details are good.

Icemark

glad you are mirroring the site though... big tumbs up

silverrotor

iTrader: (1)

I ran an additional wire (8 gauge) From Alternator to the Battery. I saw an upwards of approx. 1.5 Volts @ Idle. And that was before I upgraded to a FD Alternator.

Doing this wire mod places lesser strain on the Electrical System.

Black13B

iTrader: (1)

the stock wire coming from the alternator looks to be in NO way bigger than 10 gauge.. i would guess its a 12 gauge though.. its soo tiny!

im at work now: on the way home im going to swap in the cavalier battery (still in the back of the 7 from when i took it to the ottawa meet ).. ill take note of any similarities.. then tomorrow morning im going to add a 6 gauge (cause i got some layin around) from the battery to the alt.. then same deal: note any changes..

Black13B

iTrader: (1)

the cavalier battery is guaranteed to be good.. cavalier had NO charging issues and no battery issues - its a tough battery..

i took it to ottawa incase myself or anyone else had a power problem..

HAILERS

87..

Black13B

iTrader: (1)

my stock voltage gauge is off a bit..

when it reads 12.2 the aftermarket is telling me 13.3..

found that out of the way home yesterday

the weathers been too shitty to swap batterys and add that wire.. but its better today so ill do it today..

Relisys190

iTrader: (4)

Silverrotor. you said that you added a wire from the altenator to the battery. are you saying that you added a 'ground' wire from the bracket to the negitive battery?? or the from the acctual output to the positive side of the battery. I am confused on this subject. Because Icemark said it would be ok to add a wire from the alt. output to the underhood main fuse (80amp) But would it be ok to run from the alt. output directly to the positive side of the batt?

thanks.

-Markus

Wankel7

Alternators produce less voltage as they get warmer and warmer. Although 12.6V is low. Just some more info.

James

Black13B

iTrader: (1)

its fine..

alternator power output to battery +

i just went to crappy tire and picked up the stuff, im about to make it.. (4 gauge)

Black13B

iTrader: (1)

alright just hooked up that extra 4 gauge

heres whats different..

doesnt matter WHAT loads there are, if im above idle, it WILL charge at 14

BUT, as soon as it enteres idle, it will charge low, and with more loads, even lower, still just above 12 with all loads on.. (wipers lights radio)

but the voltage doesnt slowly drop as the revs go down.. its either 14, or not.. as soon as it hits idle, it goes BOOM back down to 13/12.5v

as soon as i tap the gas BOOM 14 until it enters back into idle.

im thinking 3 things:
-toasted battery (the cavalier one wouldnt work, wires arent long enough by a few inches to reach the terminals maybe i can try a new battery from work)
-alternator not turning fast enough to produce decent output at idle engine speed
-short in wiring somewheres.. or SOMETHING with the idle circuit or something.. as soon as the computer hits idle, BAM down goes the voltage. like i said its not slowly dropping as the engine speed drops, its instant..

comments anyone?

Black13B

iTrader: (1)

i was told by an electrician at work that the battery may have a "battery short" in it.. he said the alternator may be working its *** off to keep the volts up on the battery, then as soon as the lights come on it cant keep up with the power being drawn..

but that was last night before i added this wire..