Alternator wiring....

[Soundguy]

Many of the gm 10-s1 1 wire alternators I've seen do need high engine rpms to innitially excite.. but then once excited, still charge as low as 500 rpm. That's why i don't like those.. i much prefer the 3 wire jobs that use an isolated #1 terminal to excite, and can excite / charge at 500 rpm.. etc.

No need for a tach.. just jazz the engine and see if yuo get power come up on the charge stud.

As for negative ground.. -most- alternators are.. though you -can- get isolated and positive ground ones.

As for internal resistor coil? Probably a misnomer... most 12v coils that are 'real' 12v coils simply have the correct primary resistance designed in the windings.. not thru using an included power wasting resistor. An example of a true universal 12v coil that uses no external resistor.. and does not incorporate an internal resistor is a NAPA IC14SB.. about a 15$ item.. Way better than using a 6v coil and dropping resistor on a machine..

Soundguy

 

[skipmarcy]

Soundguy told you right - the 1 wire altenators require a minimum rpm's to excite and then will charge at any rpm until you shut it off again. No, you cannot check altenator output the way you described. The wire to the altenator must be hooked up, and the engine has to have been run up to excite rpm's - usually 1200 to 1400 for a couple seconds. You need to use a voltmeter to check for charging voltage - hook it to your battery terminals - the majority of vehicle altenators will charge somewhere from 13.4 to 14.7 volts - your voltmeter needs to read somewhere in that range to show that it's charging.While you've got the voltmeter on the battery, note what voltage your battery has while the engine isn't running too.It's possible you have a bad battery. It needs to have at least 11 volts or so to excite the altenator. Charge the battery awhile if necessary first. If your wire connections are good from the battery to the altenator and the altenator is bolted good to the engine and you don't get a reading within that range, there is something wrong internally with your altenator - period. The only positive ground systems I've ever encountered were from way back in generator days (1950's & 1960's) and just a very few imported vehicles from England etc.

 

[StevenPaul]

and the saga continues....well, feeling like an idiot again, I took my alternator to a local Mr. Alternator, which by the way is a really cool shop and very helpful and informational, I mean they have everything when it comes to machines and tons of alternators and starters. Well, I had them test the alternator and lo and behold, he tells me I have a 3 wire unit and I said no way, the guy at Auto Zone (probably just out of high school which should have been my first clue) told me it was a 1 wire. He said nope, watch this, and he showed me the results with and without the 3 wire connection. And thus, the feeling like an idiot. But all is not lost, the manager took me aside and explained to me pretty much what all of you have been telling me about the 1 vs. 3 wire setup and he told me that he could check my starter out and fix it if needed and showed exactly how to wire it up. So we (my son and I) walked away feeling victorious, at least a little anyways, like we've conquered the alternator! So we celebrated by stopping off at a junk yard lookin for scrap metal and a gas tank for a 1970 chevy truck that my son is working on. Now we're just waiting on the parts to come in for the tractor's power steering unit so we can stop the hydraulic oil leak. After that we should have the tractor back in action! Thanks again for all of y'alls help. I have learned a lot about alternators and wiring. And from all the stories I read about unhelpful or unknowledgable retail store people, I do have to give it up to the guys at Mr. Alternator, it was Saturday, they close at one, we showed up at 12:58 and they still took the time to help us out and let us "tour" the shop.

thanks again!
Steve
Anderson County, SC

 

[StevenPaul]

And here's a web page I found about alternators. It's kinda "greek" to me but I understood some of it. Some of you who understand the the "lingo" may find it useful. The topic is Alternator Secrets

http://members.1stconnect.com/anozira/SiteTops/energy/Alternator/alternator.htm

 

[Jagmandave]

What a great link, thanks for posting that!

 

[JRP]

I second the "What a great web page".
Thanks!

 

[Keoke]

HonourMe, on running a wire from the trigger post on the solenoid to the + side of coil for a higher voltage shot to coil while cranking.
This cannot be done unless a very high amperage diode is placed in series in this lead. This diode would prevent coil voltage (6 to 9v) from back feeding into solenoid winding while ignition is on. Solenoids use for by-passing ballast resistors while cranking have a special terminal for this purpose. GM marks their by-pass terminal with the letter "R". A cheaper way to go for is buy a Ford starter relay which comes with the by-pass contact built in, this terminal is marked "I" for ignition.
Note some people call the Ford relay a solenoid but is more relay then a solenoid. Solenoids typically do mechanical work (door locks, starter drive engagement, etc.) However, the Ford relay does have a moveable core (solenoid trademark) which makes it kinda of a half solenoid and half relay gizmo.
Also, if an ignition coil primary wires are reversed from their correct polarity the coil will still work. However, the secondary voltage required to ionize all gaps (fire the plug) will be 30 to 40% higher then normally needed to do the job.
A point operated ignition will give some where between 25 to 30 kilo volts in good form.

cheers,