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Old 08-24-2006, 07:14 AM
Triple G
 
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Alternator Replacement

Recently I replaced my original alternator (the one that came with the Hot Rod) with a 100-Amp Chrome version from Summit Racing Equipment. Both models were 1-wire setups with internal regulators. The original had a small colored wire (purple), maybe 3" long, that ran off the alternator post to a slotted tab connection around the side of the alternator body. (There were two tabs ... one left & one right.) The 3" purple wire connected to the tab on the right. I'm guessing that this wire was the way the internal regulator was hooked up on the model? The Summit chrome replacement has a rubber plug in this area & says not to connect any external wires?

My question is this ... after installing the Summit chrome alternator, I'm seeing 12-volts register on my volt meter. I was use to seeing just below 14-volts on the original alternator. What gives and is this a problem?

Thanks for any help.

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Old 08-24-2006, 07:51 AM
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Alternator Replacement

There have been some posts on this, I just posted one the other day, so the text of that post is below.

Questions: Did your previous alternator have wiring from the small plug on the alternator? did you replace that plug?

The fact you are seeing only 12 volts at your voltmeter is very important. Instead of getting 13.8 volts to all the accessories (which are connected at the main electrical junctionj block) now you are getting 13.8 volts out at the back of the alternator, and almost a 2 volt drop.

here is the text of my last post on this topic:

Terminal 1 is for a light on the dash, and is optional. In other words, the alternator will charge just fine whether you connect it or not. GM connected it to one side of a bulb, and the other side of the bulb connects to switched, fused battery power.

Terminal 2 is for "remote voltage sensing". GM ran a small gauge wire from this terminal to the main electrical junction block, not the back of the alternator.

Electrically and on paper, it all looks the same -- wiring Terminal 2 straight to the battery, back of alternator, or main electrical junction block should work, right? The alternator will charge when Terminal 2 is jumpered to the BAT terminal, and the wiring will look cleaner

- BUT -

and this is the big deal -

this simple connection really needs a small gauge wire run to that point where all your fusible links and/or fuses are tied together to the battery feed, which is the main electrical junction block.

Why? The voltage at the main electrical junction block is lower than at the back at the alternator: there is a voltage drop through the wire from battery to the main electrical junction block. On most GM cars that's a long wire and volt or more is lost in it.

The remote sense connection to the regulator tells the alternator to crank out enough volts to bring the main electrical junction block up to 13.8 volts or more, insuring all the accessories and ignition get proper voltage. Your car will have low system volts if you jumper Terminal 2 to the battery or alternator, so take the time and wire it all the way back to the main electrical junction block.

Jon P
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Old 08-24-2006, 04:28 PM
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Doc here,

Slightly confused here..

Are you running a True 1 wire set up or a 3 wire CONFIGURED for 1 wire? or a 3 wire where a 1 wire came out..(or something someone "Created" )?

If it's one wire, that's all you are going to have .. going to the fuse link and system buss terminal point..

On a one wire, a lot of times after you start the engine , It takes a throttle kick to wakey~Wakey the Alternator...first charge of the day..(you can under sling pulleys to overcome this..)

Also, before replacing Stuff..and troubleshooting .. check you voltage at the Battery with a DVOM , DCV, V X 50 or autorange, at Charge, (engine running) and Verify that the 12 volts the panel gauge is reporting is accurate and not really 14.4 volts. It may have been damaged when the past resident turned in it's 30 day notice..(old alternator took a dump.)

Also, and most commonly overlooked, USE the ground lug on the Alternator..to a proper hard ground at your ground buss bolt. The Mounts can corrode and insulate ground from the alternator ...

Doc
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Old 08-30-2006, 01:21 AM
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Just going to restate what's said above. The unit you took out was not a true "one wire". That is why the purple wire was installed. This standard internal alternator picks up the voltage reading from the purple wire and determines the charge necessary. This will work at low RPM without any problem.

The new real "one wire" with the plug has a self exciting regulator in it. Problem is that it does require some RPM to kick it in. So a slight wrap on the throttle is necessary go get things going. It can sit there all day at idle without charging, but once energized it will continue to charge at idle.

Most one wire units can have the plug removed and converted to either a true three wire unit, or even jumpered like your original.

Either that or you have a D.O.A. alternator.
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Old 09-21-2006, 03:31 PM
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Alternator Replacement

Just wanted to say thanks to everyone for your posts and let you all know the end results. After much discussion, some minor trouble-shooting and Summit Racing's Tech Support, I determined that the replacement chrome alternator was defective. (Like lust4speed said, "D.O.A.") I returned the Summit Racing model to their Tallmadge, OH store (no problems - good outfit) and purchased a POWERMASTER version of the same thing. It cost $30.00 more, but like I realized a long time ago in my life, you usually get what you pay for! I installed the PowerMaster and started her up, instantly over 14-volts on the dash gauge!!! I knew I couldn't have screwed things up that bad on an existing set-up with only one-wire. Again, thanks for all your help and ideas.
GGG
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Old 09-21-2006, 04:40 PM
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Doc here,

Thanks for posting back the fix!

Glad to hear it's running and road~worthy again!..Free is Good! except for your time..and that was compensated also..with the "Just because it's new , Doesn't mean it good!" lesson! (probably the hardest well have to believe it too..)

Happy Roddin'

Doc
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