Generator light on, only getting 13V - Team Camaro Tech
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post #1 of 7 (permalink) Old May 10th, 06, 07:47 AM Thread Starter
 
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Generator light on, only getting 13V

I'm hoping you guys can help me out with this one. My generator light is on, and I can only get the alternator to put out about 13V. Here is a run down of how my system is setup:

Battery in trunk
remote solenoid in trunk as well
8 gage wire from battery side of the solenoid to a junction on the firewall
10 gage wire from alt + to same junction
10 gage wire from voltage sensing terminal on external regulator to same junction
main power wire for dash connected to the same junction
brand new alt as of yesterday
brand new external voltage regulator as of yesterday
Optima yellow top

I get the same voltage readings whether it's at the + terminal of the alt, at the battery in the trunk, or at my junction on the firewall, so I don't think it's a problem with grounds or voltage drop in any wires.

My car has been apart for over two years, and I just got it back together. I can't figure out what's wrong. The only part of the charging system that has not been replaced is the small cylinder that attaches to the voltage regulator.

Any help is appreciated. I looked through the archives, and could not find any threads where someone actually solved a similar problem.

Thanks
Ken
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post #2 of 7 (permalink) Old May 10th, 06, 08:50 AM
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Re: Generator light on, only getting 13V

very odd. I'd expect if it was giving you 13 volts, the gen light would not be on.

In the elctrical basics sticky at the top of the electrical forum, there is an article on the external regulator system. This artivle includes voltage checks and proper readings at every connection in the system and some troubleshooting tips. Give it a whirl.





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post #3 of 7 (permalink) Old May 10th, 06, 10:43 AM
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Re: Generator light on, only getting 13V

There should be a bonding strap between the regulator frame and the radiator support IF the reg was mounted on the rubber nuts.

In fact, the regulator base and the alt case should be at the same potential, ground.

The GEN light has ignition voltage on one side and the sense'd voltage on the other side of the bulb to turn it off. Could be wiring fault at the bulkhead connector or at the regulator.

You will get some cable losses from the alt BAT stud and to the positive battery post. Your DMM will show these losses as go from one spot to another. Get a long length of 14 or 16 AWG and use it to connect to one spot, but before you do this, connect the long wire and meter lead together and let the meter zero itself. Then connect to the alt stud and battery post, not to the terminal lug, you will not be getting a true reading of voltage drop. Max voltage from the stud-to-post should be 0.5 VDC.

Charging voltage should be across post-to-post. Adjust regulator to increase voltage, which will increase charging current.

I would make sure first, the negative battery post, engine block, alt case, regulator base, and body are all tied to each other. This gets them on the same reference/ground point.

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post #4 of 7 (permalink) Old May 10th, 06, 11:31 AM Thread Starter
 
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Re: Generator light on, only getting 13V

Thanks for the replies. For my grounds, I have a 1 gage cable from the negative terminal on the battery to the engine block. I then have an 8 gage wire from the engine to a junction on the radiator core support. I have a ground from the alternator to the same junction, and from the regulator to the same junction. I don't doubt I need to improve some of the grounds for the rest of the car though, such as the marker lights in the rear of the car. I will probably make another junction in the rear of the car and tie all the grounds into it.

About adjusting the voltage on the regulator, how do you do that? I didn't even know it was adjustable to be honest? Also, what is the small cylinder that is bolted to the regulator?

Thanks for your help. I did read through the electrical basics, and I have spent a lot of time on MAD's site. I'm learning, but electrical systems are hard for me to understand sometimes.

Thanks again.
Ken
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post #5 of 7 (permalink) Old May 11th, 06, 05:01 AM
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Re: Generator light on, only getting 13V

Quote:
Originally Posted by BB69
About adjusting the voltage on the regulator, how do you do that? I didn't even know it was adjustable to be honest? Also, what is the small cylinder that is bolted to the regulator? Ken
The small cylinder is a noise filter, a capacitior, to filter out some of the voltage spikes caused by the mechanical regulator.

Regulator adjustment can be done at an alternator rebuilding shop. Take your alt along and let the tech adjust both as a system.

Or, if you really want to tackle the job, remove the reg cover, and the left coil, if reg connector is pointing down, is the voltage coil. You will find a small spring on the side of the coil between two tabs. Some regs have an adjustment screw, others do not. Use the screw or bend a tab to lengthen the spring. Lengthening the spring increases the charging voltage.

There are other factors used in adjusting voltage with an older regulator model. Battery charge state, regulator temperature, engine rpm, electrical load, and battery temperature. All these factors go into the equation to properly determine the voltage setting.

What would I do? If the shop could not adjust the reg for 14.4 volts, then I'd buy a Wells VR715 regulator. This is the electronic version of the mechanical. Just transfer the cover from the old one and it looks OE.

If you want to try and adjust yourself, after running the engine for 5 minutes at fast idle, charges the battery from using the starter, measure charging voltage at the battery posts. Turn off engine, remove neg cable from battery, remove reg cover, measure length of spring and record for future reference, lengthen the spring alittle, replace cover, cable and remeasure charging voltage after 5 minutes of running.

Take small steps in adjusting until 13.8 to 14.5 volts are reached. However, with all electrical loads applied, lights, heater, wipers, voltage should not be below 13.5, loads off, engine running at idle, ignition only, voltage shouldn't go above 14.5 volts.

Running the car for two weeks at a time and following battery charge state, this will determine the charging of the battery.

And it does read like you have all connections covered. Glad to read 1 AWG cable is being used.

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post #6 of 7 (permalink) Old May 11th, 06, 07:31 AM
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Re: Generator light on, only getting 13V

Note that with a full electrical load, it would be unusual for an external reg system to maintain 14 volts below about 2000 rpm.

I run a 61 amp w/a wells reg. It will manage 14.5 volts at idle with nothing on but the motor, but even then the voltmeter moves in time with the turn signals. With the headlights on and the stereo cranked, idle voltage will drop below 13, and sometimes I can see the voltmeter move with the bass.

I'd consider this both normal and acceptable. Car has had the same battery in it since before I bought it, and the battery stays charged, which is of course the ultimate goal of a charging system.





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post #7 of 7 (permalink) Old May 12th, 06, 08:26 AM Thread Starter
 
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Re: Generator light on, only getting 13V

Thank you guys for the detailed replies. I had my open track day yesterday, and even though the I couldn't get the generator light to go off, the car ran well all day. I now have time to go through the whole electrical system in detail. I am thinking about replacing the whole harness. When I was disconnecting the old aftermarket gauges the previous owner had installed, I realized he had wire them up with solid core wire. I had found some of his previous gems before, but this was the worst.

I will try to give you some updates as I start to solve these problems.

Thanks again.
Ken
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