charging blues

[Patronus]

First off, I have been reading threads on this subject for hours, and my head hurts.  
Im not very elect. savy and really need some help. Last night was the first time I drove with headlights, and it drained the battery in about 2 miles. Its a new alternator and has 3 wires. 2 go to the post and single green to tab. I've seen Nachos thread on a re-wire but find it extremely hard to follow. Does anyone have clearer instructions on what I believe to be the bulkhead bypass?
Also: fyi: multimeter reads 12.82 sitting
                                      12.55 running
                                      12.22 running w/lights
those don't seem right

[Nacho-RT74]

at the end only thing you need to make is open a hole on firewall and run new wires from alt to ammeter and get back from the other ammeter stud to starter relay, thats all.

Check the ammeter for loosen terminals... that could be a reason, then the bulkhead terminals

[Patronus]

I cleaned up the v. reg. mount and checked firewall connections. Still only 12.5 v running. I have the alternator wired with a black wire and a purple wire wired together to the stud on the alt. and then a green wire with a tab connector to a male prong. Does this sound right? Its a NAPA alt. I also have the small style voltage regulator, should I be using the larger Electronic voltage regulator? Is there a way to test it?

[Nacho-RT74]

I'm talking on back of cluster at ammeter studs ... also terminals at bulkhead.

yes you have it wired right. violet is the hot source to horn relay up to 69s mounted at radiator core support. On 70 were changed to inside the cab

black is the alt output

green is the regulated field coming from regulator.

[A383Wing]

you don't say what year car....and why do you have a black & purple wire to the alternator main batt terminal??

12.5 would indicate to me that it ain't charging....either something is wired wrong, or possibly regulator or alternator is bad

[y3chargerrt]

Can't really tell but is the second field terminal grounded at the alternator?

[tan top]

you don't say what year car....and why do you have a black & purple wire to the alternator main batt terminal

thats the stock set up black & purlpe wire to the alternator power stud, the purple  wire takes power to the horm relay

Can't really tell but is the second field terminal grounded at the alternator?

thats what i'm thinking  , got a better picture ??

[Nacho-RT74]

is roundback... unless is a 70/71 alt whih got 2 prongs, this should be only one prong kind which is the one what gets the wire from regulator.

the other brush is attached directly to the chassis. IF THIS BRUSH HAS A PRONG, needs to be grounded. You can replace the isolation washer for a metallic one, and cut the prong to save from wire this one accidentally.

OR ground it with a wire to the chassis, just that the first option I say gets a cleaner look.

or IF this alts is two prongs, you can convert to lates electronic regulator. Is an easy installation, an splice to hook the regulator plug, and a new wire running to alt

[Patronus]

Thanks Nacho, yes from what we've found out it is the wrong alt.

[Patronus]

Here's the old one I took out and the new one. I don't really see any difference?? I don't think I have it hooked up right. I only have those two connections, the black/purple and the green. Am I missing something?

[tan top]

  thats odd looks like someone  has tried to turn a single field alternator  it to the later square backed duel field  
 what was the reason you was changing the alternator ?  have you done any wiring work ? did you buy it like this  ?? what type of voltage regulator have you got  has it got modern guts in side ??

[Patronus]

Hey TT. I was changing the alt. just to clean up the engine bay and kept it for a spare. I haven't done much wiring, just got rid of the elec. choke. I have the older voltage reg. (see pic). So do you think both these alts. are wrong? I bought it with the older alt. it ran fine, but I didnt really drive it much. What alt. should I run? Pic? Model #??

[Nacho-RT74]

ok... the one of the top, THE PRONG ADDED DOESN'T MAKE ANY SENSE!!! THE BRUSH IS ALREADY GROUNDED BEING DIRECTLY ATTACHED TO HOUSING. Also, you can wrongly hook up the green wire there, what on old regulators kind, drives POSITIVE so one you put the key in RUN will be shorting out.

On second one, it is in effect a 70/71 round back alt used to be match with electronic regulators. The prong at 12 o'clock was cut what is nice to save from wrong wire hook up and cause a short once grounded, but then NEEDS to be grounded. You can replace the isolation washer underneath the retaining screw, using a REGULAR STEEL WASHER, and done! you'll be grounding the brush to get the negative field liek earliers did. The isolated prong will get as must be the green wire getting positive from regulator and VOILA! magnetic fields are both inside the alternator to create power.

[Patronus]

also, I put the old one back in and the alt. gauge reads much steadier, yet at idle shows -5 and +5 at about 2000rpm. Multimeter still only reads 12.6 running...  

[Nacho-RT74]

OR you can modify your system to use later regulators... one wire added up to alt ( blue ), get back an untouched brush prong, keep the isolation washer, couple of splices to the regulator pigtail and done.

Note, these alts are not quite efective under low RPMs

[Patronus]

Thanks Nacho, I know you can help, if I could just understand your typing... so I will reinstall new alt. (lower in pic) and hookup like I had it, but will have to remove the rubber washer under the other prong and replace with steel?

[Patronus]

this?

[Nacho-RT74]

sorry if my typing is not easy to you... if there is something you can't understand let me know. Being the english not my mother language and using english just here on boards sometimes I don't take in mind what mistakes I'm making.

Yes, you need to ground that brush. Use a metallic washer instead the plastic, rubber, bakelite or whatever isolation  materiall for the washer being used there will make the job.

That washer normally attachs between screw and prong, not underneath the plastic housing

You also can bend what still rest of the prong below the isolation brush housing and will help even more on a good ground.

with that alt, you can also upgrade for later electronic regulation system whenever you want, just replacing that cut brushed prong for a new one and getting isolation washer back, ( so don't trash the isolation washer just in case ) and getting the newer regulator, pigtail and extra wire

[Patronus]

Please Nacho, no need to apologize, if anything I should, as elect. is a foreign language to me. (I am willing to learn though.)
I have the older alt installed and quickly ran a wire from the additional prong to the chassis with no change in readings.

[Patronus]

Given the choice I would like to run the newer alt. Although personally, I can't really tell a difference. On the new one both prongs have FLD next to them. On the one I removed (pic w/ washer) it does not have an isolation washer on top of the cut prong, only the one under coming into contact with the housing. Im not too concerned with original so... were I to reinstall newer alt. and ground wire to chassis from said brush I should be ok? I dont think this thing was ever right, please, let me thank you guys for your patience. Someday I might have 14v...

[Nacho-RT74]

the washer was installed wrong, simply that.

No need for a wire if you install the metallic washer on the right place. The ground provided by the screw into the alt chassis and then making contact with prong through the metallic washer is enough.

if you want extra added ground, bend what still rest of the prong underneath the brush isolator and will make even MORE chassis contact.

the advantage of newer regulators Being electronic is they are less noisy to electronic ignition modules, against the mechanic relay kind old regulators.

NOTE... hard to reach 14 Volts from these charging systems... 13.5 is good anyway

[Patronus]

I will reinstall the new alternator with a washer on top to make sure we have a ground. I will check to make sure with a test light from the pos of battery. (This is basically how I had it before.) 

[Patronus]

Well, no luck. I have a ground at that brush but its still not charging. The only time I had a reading on the plus side of the interior gauge was with the old alternator. Yet even with that its still only 12.5 v. Im guessing a new voltage reg?

[Nacho-RT74]

feed the field at prong with 12 volts to check what you get... that will make FULL FIELD ( bypassing regulator ) so don't rev up the engine

are you sure you have clean bulkhead terminals and clean and tight ammeter wires on back of cluster ?

[Patronus]

So I will start the motor and use my test light from pos of battery to alt. stud and then check battery with meter?