Volts drop to 10.5 with lights on - Team Camaro Tech
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post #1 of 8 (permalink) Old Jul 18th, 15, 04:00 PM Thread Starter
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Ken
 
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Volts drop to 10.5 with lights on

I never knew there may be a problem until I got VHX gauges in my car and it shows the volts. I went for a drive and turned on the lights and the gauge started flashing and showing 10.5 volts at idle. I don't know what it is when I am driving with the lights on because it goes back to the speed in that LCD window and I just haven't changed that setting.

But 10.5 at idle with just lights on seems way too low. What happens when I get my A/C in and stereo turned on.

It's a crate 350 motor with about 10,000 miles on it. Probably all original wiring and its a 1968 camaro convertible.

So where should I start with this?
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post #2 of 8 (permalink) Old Jul 18th, 15, 04:12 PM
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Al
 
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Re: Volts drop to 10.5 with lights on

Standard headlights?

If it's an original style 10DN alternator they aren't known for very good idle output.

Could be a dirty or out of adjustment mechanical voltage regulator or it could be a failing alternator to name a couple of things.

What is the voltage at the big wire on the back of the alt at idle? At 2000 RPM? Should be about 14.2.


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post #3 of 8 (permalink) Old Jul 18th, 15, 04:14 PM
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Re: Volts drop to 10.5 with lights on

1/ your idle speed a little low.. 50 or 100 rpms makes a huge diff on a good alternator
2/ Alternator rated too small.. air con etc ideally should have at least 100 amp
3/ worn bearings in alternator
4/ If non self regulated, the regulator may need adjusting / testing... GM built in alternator regulators are built like brick #$#%^ houses.. the whole alternator is built solid...even brushes out wear bearings... by a long way.
5/ check connections for corrosion , broken wires , clean, including battery terminals.

Dont expect a full 12.5 at a slow idle.....
A ball park check if alternator is big enough is a fast idle.. turn on everything and if headlight dim excessively the alternator is not producing enough current and get a voltage drop.

My Spelling is not incorrect...it is creative

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post #4 of 8 (permalink) Old Jul 18th, 15, 05:00 PM
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Re: Volts drop to 10.5 with lights on

Just go get a 1 wire alternator and be done with it. 120+ amp.

They're like $70.

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post #5 of 8 (permalink) Old Jul 18th, 15, 06:21 PM
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Re: Volts drop to 10.5 with lights on

Before you go and get a one wire alternator, do a bit of investigating and some trouble shooting/diagnosing first.

Where are you reading that voltage from, if its from the headlamp wiring, I'd expect it to be that low.

Also, the original alternators (if in proper working condition) when powering the original electrical demands of the 1st Gen Camaros are fine, it's the mechanical voltage regulators that fall short and usually cause the alternator to not perform at their peak ability. A solid state external voltage regulator is the only way to go for maintenance free (as far as voltage regulators go) peak charging system performance with a properly functioning 3 wire original alternator.

Take a few minutes and do some reading at the following three links:

1. ONE-WIRE compared to THREE-WIRE alternators - http://www.madelectrical.com/electri...hreewire.shtml

2. REMOTE VOLTAGE-SENSING - http://www.madelectrical.com/electri...esensing.shtml

3. BRIGHTER HEAD LIGHTS - http://www.madelectrical.com/electri...adlights.shtml

I run an original 3 wire alternator with a Wells VR715 solid state external regulator (one of the best electrical upgrades available in my opinion) and a Amico headlamp relay (the second best electrical upgrade and it could be any of the headlamp relay kits out there, I chose the Amico as it was very cost effective) and this combination works just fine. Having stated the previous, I'll add that the only real increased electrical demands of my 69 Camaro are the higher wattage headlamps and the Pertronix Ignitor III ignition system. I run a mechanical fuel pump, the original Z/28 mechanical clutch fan setup and a very small amplifier for the stereo head unit. My system puts out 14 plus volts at idle with no problem.

If you have a high electrical load thumper sound system, electric fan(s) setup for your radiator, and/or an electric fuel pump, you may need a larger alternator, but a three wire system will handle the electrical demand much, much better than a one wire system so do your homework if you go with a larger alternator before making a decision.

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post #6 of 8 (permalink) Old Jul 18th, 15, 07:29 PM
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Al
 
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Re: Volts drop to 10.5 with lights on

Quote:
Originally Posted by Gbauer View Post
Just go get a 1 wire alternator and be done with it.
Don't do that, if for no other reason than to keep your GEN light. One wire alt will make your GEN light non-functional.

If the GEN light comes on there's a good chance you lost the fan belt, which means you're likely to overheat. Other benefits to the 3 wire as well

If it turns out to be the regulator or the alternator I would suggest swapping to a 10si or 12si 3 wire internally regulated alt - excellent and easy swap.


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post #7 of 8 (permalink) Old Jul 18th, 15, 07:56 PM
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Re: Volts drop to 10.5 with lights on

I second what Al and Scott say. You can upgrade to the 12SI one with a wiring conversion kit like this- http://www.americanautowire.com/shop...conversion-kit and go buy a 94 amp one from a 1984 camaro 305 G code. Less than $100 for everything and you will not have any charging issues. Here is an example of that alternator from O'Reilly Auto parts http://www.oreillyauto.com/site/c/de...ord=alternator

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post #8 of 8 (permalink) Old Jul 20th, 15, 10:48 AM Thread Starter
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Ken
 
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Re: Volts drop to 10.5 with lights on

I'll have to really look at what I have on there now. I know they are standard headlights. I don't have a Gen light anymore since these are new VHX guages (dakota digital)

http://www.dakotadigital.com/index.c...rod/prd721.htm

I'm not sure if i have a 3 wire or 1 wire alternator but I will check all of this. I'm almost positive it's 3. One thing is when I first start the car it makes an awful noise, like a loud screech sound from the alternator (I think) but only lasts like 1 second. I've thought about replacing it just to get rid of that sound alone. I tried adjusting the belt which didn't do anything.
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