Good alternator putting out low voltage

D

duly

Member
Hello all,
Working on a 1967 Camaro RS, 327 275hp, 4 speed manual. Been trying to diagnose my low voltage problem. New alternator has been tested off the car at Oreillys, reading was 14.5 - 14.8. Put it on the car 12.5 is the max. Changed battery same thing. Belt is tight, and voltage stays at 12.5 when increasing rpm. Just trying to run down this problem, it is the only major thing I can't seem to fix.

Any ideas are welcomed, no matter how elementary, I am still learning

thanks,
duly
 
Welcome to the forum duly!!!

Sounds like your problem might be a bad connection, every connection is a voltage
drop. Measuring the voltage drop across the connection should only be a tenth or
two at the most. Good luck!

BTW, where are you measuring 12.5 volts?
 
theres three likely areas that need to be tested,
the alternator,
battery
and
connections between the two (cables) (LIKE MENTIONED previously ABOVE)
you need a multi meter to test
set the multi meter on DC 0-20 volts ,
the black common lead to the engine ground
connect the red volt test too the
ALTERNATOR VOLTAGE OUT LEAD MARKED
OUTPUT below at 2000 rpm you should see 14.0-14.7 volts with the engine running
altesta.jpg

ampmeter.jpg

cars use DC homes use AC current ,know the difference and use the correct meters

http://garage.grumpysperformance.com/index.php?threads/multi-meters.3110/

http://www.amprobe.com/Amprobe/usen/Contests_Promotions/amp-25.htm?gclid=CJGbirzF59ACFUU2gQodJ6UIqA

http://www.powerstream.com/DC-clamp.htm

https://www.amazon.com/Amprobe-AMP-...1481301013&sr=8-9&keywords=fluke+dc+amp+meter

http://en-us.fluke.com/training/tra...-digital-multimeter-plus-clamp-accessory.html


multi.jpg

your battery should run 12 volts to 12.7 volts if fully charged , when tested between the unconnected lugs
Item# 1677827

having a quick easy to use auto voltage test checker helps speed the diagnosis
16052a.jpg


as most of us who work on cars know chasing minor electrical glitches is a P.I.T.A. and it helps a good deal to have at least a minimal quality multi meter and test leads, and a scan tool, that can be used to, locate isolate and test THRU insulation on wires, and a tool to pull trouble codes and do minimal programming.

21JGPEK8GVL._SS400_.jpg

http://www.amazon.com/AutoXray-6000-EZ- ... cr_pr_pb_t

F-113_01a_c_200.jpg

http://www.fluke.com/Fluke/usen/Digital ... ?PID=55990

image_12926.jpg

http://www.harborfreight.com/5-in-1-dig ... 98674.html

image_493.jpg

http://www.harborfreight.com/ac-dc-digi ... 37772.html
pm70ca.png

assuming you have near 14 volts at the alternator output lug , now move the red test lead, on the multi meter to the battery positive post, and keep the black lead on the ground connection, it should read the same, if it reads 12 volts or less the cable between the battery and alternator must be resistance tested and read less than 1 -2 ohms
if it reads over 4 ohms its likely defective.
if it reads good the battery is likely internally damaged

chargcircuit2.gif

BATERM.JPG


DelcoWiring.jpg

the small switched red wire must supply 12 volts to the alternator as the engine starts to activate the charge circuit
alttest2.jpg

battery1.gif


http://garage.grumpysperformance.com/index.php?threads/testing-an-alternator.3222/#post-46703

http://garage.grumpysperformance.com/index.php?threads/battery-or-alternator.10003/

http://www.summitracing.com/parts/tff-8173nep/applications/year/1996
 
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Been using 2 different multimeters, just trying to eliminate the multimeter being at fault. Taking the measurement from the positive post on the alternator and also checking the voltage on the battery posts.





http://custombatterycables.com/product_info.htm

I will go out and check this stuff. Thanks
 
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You have A Delcotron 10DN Series Alternator.
External Voltage Regulator layout.
Check your Voltage regulator connections.
You may have a Modern replacement Transistor basd external voltage regulator.
Original was a Mechanical breaker points layout.
Mechanical points work.
Special file called a Rifler file is used to clean.
You adjudt points air gap as required .
Its a bit of an art to set up correct.
I have worked with them.

GM used Delcotron 10 DN on all 1963-1970.
Except 1970 Firebird & Trans Am.
State of the art at the time 10 SI relwased.
Internal voltage regulator.
Not used on Corvette till 1971.
Pontiac Firebird Trans Am was the Test Guinny Pig & passed real world tests.

10DN is just Ok.
Most had just 30-35 amps output.
Olds & Pontiac had High amp versions rated to 60-65 amps.

None put out terrific idle charge current.
15-30 amps max

10Si be better.
I like 12si & 15-17si series.
DELCOTRON CS144 Bliws all away.
My Favorite .
 
I replaced the voltage regulator before I replaced the alternator thinking it was the regulator. I will go back and double check the connections. Also I am around the third, fourth owner so no telling what might have been done previously, eventhough this car only has 20,000 original miles. Being so low miles I want to keep as original as possible.
 
You need the RED IDIOT LIGHT WORKING IN THE DASH.
KEY ON ENGINE OFF THE BATTERY WARNING LIGHT MUST COME ON.
ENGINE STARTS THE RED IDIOT LIGHT GOES OFF.

I Build custom Alternators once in a while.
HIGH AMP OUTPUT CS 144 .
On Dorian's Vortech Supercharged Tangerine Tornadoe Heavy metal Chevy here.
On Ricks Vintage For SBC 401 T-BUCKET HERE.
80 AMPS AT IDLE NO SWEAT.
 
The Idiot light on 10 DN & 10 SI used as part of Alternator Field current circuitry .
Same idiot light used well into 1980's & 1990's.
 
Well there you go. Never had the idiot light come on, didn't even know there was one. Going to check that and I have a replacement ammeter waiting to go in. Gotta pull out the service manual and get all this sorted out.

Thanks
 
Your Welcome.
The Red Charging light bulb may be Burnt Out.
Simple fix then.
 
Got the instrument cluster pulled off and this is what I found. There is a yellow wire going to the alternator warning light bulb and in my case it was disconnected. On a side note the bulb wire was being held to the back of the speedo with some clear tape, which I assume is NOT factory which means somebody might have been in here before. You can see the 2 wires attach by the black connector. I looked at my assembly manual and can't seem to find a yellow wire going to the alt warning bulb. And no when I hooked it all up bulb did not light with ignition on. I will get a new bulb and go from there before I get too worried.
IMG_0348.jpg





IMG_0349.jpg


http://garage.grumpysperformance.com/index.php?threads/voltage-is-wrong-after-alternator-swap.13580/
 
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Got the cluster out. I am trying to take my time with everything I do because this car is so original and I am a bit of destroyer of everything I touch. Found the problem.

IMG_0350.jpg
 
Excellent. Looking at new circuit board as we speak. My fear is what else has been done to this low mile car that I need to properly fix? Damn POs, fix it right the first time and know it was done right. Guess I need to take my time and look at everything.

Thank yall for the help
 
providing that individual help, to the newer guys is the main reason I built the site and why many of the, older and more experienced and skilled member's post here
 
If you have time today, connect your Test light in place of the Red Idiot dash Generator warning lamp.
Start your Camaro and see if the 10 DN Alternator is charging.
Voltage output needs to be ar 12.6 Vdc at the battery.
All Voltage Regulators have a Temperature compensating circuit.
As temps outside drop down to 32F Freezing alternator voltage increases.
32 F you may see 15.1 vdc and its OK.
14.4 - 14.6 VDC at 75 F I prefer.
 
Many old Low amp output GM Alternators struggle to put out 13.5-13.8 vdc at full current test loads at rated outputs.
 
Also old alternators often have been rebuilt at least a Dozen times.
Inferior rebuild parts used.
Virgin original cores prefered but Hard to find today.
 
I learned decades ago to swap to a 140 amp-200 amp alternator,
as the stock 75-105 amp alternators on muscle cars and earlier corvettes are marginal at best/
if you shop carefully they can usually be found locally at some alternator re-builders for under $150
both my corvettes have 200 amp versions purchased NEW for under $250
while that may be over-kill to some I find the electric fans on the corvette and ignition and head lights work noticeably better

https://www.dbelectrical.com/alternators/automotive/chevrolet/corvette/5-7-liter/

http://www.ecklerscorvette.com/corvette-alternator-140-amp-chrome-power-master-1969-1982.html
140ampa.jpg

140ampb.jpg



http://www.dbelectrical.com/p-4516-high-output-chevy-3-wire-alternator-140-amp-65-85.aspx
140ampc.jpg

140ampd.jpg
 
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