Have replaced the Alt with one with an internal reg. Now I have the #2 jumped to the battery post on back and the #1 to the ignition. The Alt only charges to 12.3 and is only enough to keep it running but not enough to restart after I shut it off. I brought it to Auto Zone and had it tested and they said it passed. This is a 63amp Alt. I'm running electric fuel pump, dual electric fans and ignition box as my add on electrics. I tested the back post behind Alt and that also only reads 12.3. If I step on the gas it gets up to 12.5 - 12.6. Any thoughts on why? It should be around 14.7 or so to keep the battery charged. Help!
How much current are you getting from the alternator? I wonder how much current and voltage all of your addons consume. No way anything near 63 amps. I'd think the alternator was not putting out.
What alternator do you have? 2 wire, plus the battery wire? You might not have the regulator sensing wire connected correctly.
I have what Auto Zone say's for a 1972 Chevy Chevelle 7.4L and it's their brand DL7133. I checked the wire for 1 and 2 and re crimped them tight. The white wire to #1 is from new Painless wiring that was installed. The Alt charges but only to 12.3 - 12.5. I believe the #1 turn on wire only has to be from ignition to turn on Alt when key is on. That should be a 12v hot when key is forward.
Do you have a amp clamp or a meter? Your current is inversely related with resistance to voltage. The whole v=ir deal. I would return the alternator and get another from somewhere else if it was me but someone else here may have some more wisdom.
Why does the alternator discription say: <TABLE id=prodspecs cellSpacing=0 cellPadding=0><TBODY><TR><TD>Alternator Regulation Type:</TD><TD>External</TD></TR></TBODY></TABLE> http://www.autozone.com/autozone/parts/Duralast-Alternator?itemIdentifier=333419
Good catch. Based on the description and the photo showing the parallel spade terminals, it is indeed an externally regulated unit. Whoops! Devon
Your a Genius! I asked them and told them I needed it to be an internal regulator as I do not have my external hooked up. They told me yes it was internal but clear as day you looked it up and I see it's not. Friggin young kids behind the counter. Thank you as I'm going back today.
I have had better luck with salvabe yard alternators. You really need a CS series alternator. The best of those are from LT1 Roadmasters, Chevy Caprice etc. They are 140 amps. In general the CS series are the most powerful GM makes. If you want a really good one have Jamie make you a custom. Just a little more than Autozone and you know they are put together with the good parts.
Since this has been resolved, I have another alternator question. I have a 105 amp, with internal regulator. It has three connections (SI type connection & the heavy red wire.) I would like to use it as a one wire alt, so can I just hook up the heavy red wire & leave the SI connection un-used? thanks,
See, your first mistake was going to Autozone and expecting the person behind the counter to actually know something about auto mechanics. They are more likely to know lots about computers, but that's it.:laugh: Your second mistake was asking him to look up a 72 model year car. All alternators were externally regulated that year. So that is what you got. Internally regulated alternators came in later model GM cars. Not sure when it started, but if you ordered one for a 75 car, you would get the internally regulated alternator. It's actually very easy to tell the difference. The plugs are different between the 2. The plug position is also different. On an internally regulated alternator, it goes in on top. On an externally regulated alternator, it goes in at the back. This is an internally regulated alternator.
Frank On a 3 terminal alternator, the terminal marked "1" has the indicator lamp connected to it and that supplies the start-up current needed for the internal regulator. The indicator light must get power from the igntion switch so when the ignition switch is off there is no current drain on the battery. The terminal marked "2" is the sense line for the internal regulator and is connected to the point that you want regulated at the set regulation voltage. The short answer is the SI connection must be used. Paul
Ok so got a new alternator today and it did not fix the problem. Now I'm reading 12.5 at the battery. WTF! There's gotta be something I'm missing here. There is three wires on the back on the post. One directly to the trunk battery, one that jumps to #2 on the plug and a third that the painless wiring kit said to hook up from the fuse box. Other than that the #1 plug is attached and said Exciter/Coil and that comes from the new fuse box. That exciter seems to be HOT even when car is off as I tested it down the wire away from the alt. Any other suggestions?
A quick note here regarding the ground. Check for voltage on the alternator housing to ground. If there is ANY voltage hare, you might try fixing the alternator ground, which should be the case to the engine. Just a thought.
I'll check tomorrow. The ground on the back of the alternator is not hooked up. I just have it grounded through the bolts to the block.
That's fine,the SI units dont have a ground post.My question is,what type of harness did you order,for internal or external alternator?
