Overcharging, even with field wire off. Solved.
#2429673
01/05/18 11:12 PM
01/05/18 11:12 PM
|
Joined: Nov 2012
Posts: 86 Alabama
WarEagle1
OP
member
|
OP
member
Joined: Nov 2012
Posts: 86
Alabama
|
'70 Cuda with square-back alt and stock type VR. Ran today for the first time in a month. Was charging at close to 16V. Thoroughly checked wiring and connectors and engine/body grounds. Ran it with VR disconnected and then with green field wire on alt disconnected and nothing helped. Is this an internal alternator issue? I ran the 110V test lamp test (in the FSM) but it failed on every alternator I have. I don't trust it. Anybody ideas? Please help. Thanks.
Last edited by WarEagle1; 01/06/18 11:33 PM.
|
|
|
Re: Overcharging, even with field wire off. Whats up with this?
[Re: WarEagle1]
#2429674
01/05/18 11:16 PM
01/05/18 11:16 PM
|
Joined: Aug 2007
Posts: 6,095 Valencia, España
NachoRT74
master
|
master
Joined: Aug 2007
Posts: 6,095
Valencia, España
|
Brush grounded? Probably broken isolator?
With a Charger born in Chrysler assembly plant in Valencia, Venezuela
|
|
|
Re: Overcharging, even with field wire off. Whats up with this?
[Re: WarEagle1]
#2429684
01/05/18 11:32 PM
01/05/18 11:32 PM
|
Joined: Nov 2003
Posts: 36,040 Lincoln Nebraska
RapidRobert
Circle Track
|
Circle Track
Joined: Nov 2003
Posts: 36,040
Lincoln Nebraska
|
2 field terminal alt with the blue wire feeding it switched 12V & the green wire pulled off of the other alt male terminal & it is full fielding? If so then what Nacho said, an alt problem. (if not holler back). eyeball the brush assys for any visual grounding then pull the blue wire off of the other alt male field terminal & ohm both the male alt field terminals to the nearby case & there should be NO continuity (& ohm em to each other). You might take the brushes/holders off & inspect/reinstall (something hot is touching ground). the field circuit is improperly dead shorted to ground makeing it full field. Do not let it FF for more than a few seconds at a time, just long enough to see if each of your corrective procedures is fixing it. & have all lights/accessories off during this
live every 24 hour block of time like it's your last day on earth
|
|
|
Re: Overcharging, even with field wire off. Whats up with this?
[Re: WarEagle1]
#2429729
01/06/18 01:11 AM
01/06/18 01:11 AM
|
Joined: Nov 2003
Posts: 36,040 Lincoln Nebraska
RapidRobert
Circle Track
|
Circle Track
Joined: Nov 2003
Posts: 36,040
Lincoln Nebraska
|
"at rest" the field circuit ain't grounded (you have no continuity to the alt case) but if it is full fielding with the blue wire field lead plugged in & nothing on the other male alt field terminal then the field circuit has to be grounding/full fielding while it is "running". Am I seeing this correct per your description? If so I would take the alt in to O'reillys for a free check & let them spin it & tell them how it is acting so they can not only check max full fielded output (their std procedure which ain't the issue here) but see if they can get it to FF at a lower RPM (like it is doing now). We'll get it
live every 24 hour block of time like it's your last day on earth
|
|
|
Re: Overcharging, even with field wire off. Whats up with this?
[Re: WarEagle1]
#2429833
01/06/18 11:32 AM
01/06/18 11:32 AM
|
Joined: Aug 2007
Posts: 6,095 Valencia, España
NachoRT74
master
|
master
Joined: Aug 2007
Posts: 6,095
Valencia, España
|
ok, let's see... dual field alts get both brushes isolated, one for constant positive the other one for regulated negative. Hence both needs to be isolated.
positive ( blue ) comes straight from ign switch.
negative ( green ) is sourced by the regulator.
This is a non brain deal: an alt sourcing is somehow getting both fields to still work. With regulator unplugged, it is getting still both fields on whichever form. If blue wire is still plugged to field and green is unplugged and STILL is feeding, something is shorted to ground feeding on rotor.
Once I got 18 to 24 volts reading ( depending on RPMs ) and discharge on ammeter. After schatch my head for couple of hours just found vent vanes were getting some friction with diodes leads coming from stator while spining. Just bent a bit the stator leads to diodes bank and done. Maybe a diff problem than you but meaning with this a fail like this is a straight or internal short, somehow.
Now about ohms testing... allong the years the rotor ohms reading changed a bit from 12 to 7 ohms between leads. However no matter what, it must be isolated from chassis if reading straight to rotor tracks. Now, reading between brushes, a single field will be grounded JUST via the grounded brush, but on dual field alts they still must be show non continuity with chassis, no matter what.
If you get ground continuity between brushes, something is shorted to ground. It can be brushes itself or rotor ( I have got maybe half of dozen damaged rotor, is my main fail ). HOWEVER a Rotor grounded can get two kind of damages: continuty on windings and still shorted to ground OR broken wire and one of the leads shorted to ground. Both will cause diff fails. I have not analized that, but MY THOUGHT is the first case can keep still working but full fielding... second case not ( that's for sure ). MAYBE you are getting the first case ?
A damaged diode will cause still nice voltage but not enough charge
many other fails can appear on alts, but I have not analized everyone
on a note appart... IF the brush the green wire was connected is grounded YOU GOT LUCK the blue wire is/was not conected there because that will burn the wire up to ign switch and even blown the fuse link, burning all around.
Last edited by NachoRT74; 01/06/18 11:49 AM.
With a Charger born in Chrysler assembly plant in Valencia, Venezuela
|
|
|
Re: Overcharging, even with field wire off. Whats up with this?
[Re: NachoRT74]
#2429957
01/06/18 02:42 PM
01/06/18 02:42 PM
|
Joined: Jan 2003
Posts: 25,786 Rio Linda, CA
John_Kunkel
Too Many Posts
|
Too Many Posts
Joined: Jan 2003
Posts: 25,786
Rio Linda, CA
|
If the blue field was shorted to ground you'd have a smoking wire, if the green field was shorted to ground you'd have maximum voltage output.
The INTERNET, the MISinformation superhighway
|
|
|
Re: Overcharging, even with field wire off. Whats up with this?
[Re: WarEagle1]
#2430397
01/07/18 09:30 AM
01/07/18 09:30 AM
|
Joined: Aug 2007
Posts: 6,095 Valencia, España
NachoRT74
master
|
master
Joined: Aug 2007
Posts: 6,095
Valencia, España
|
It was tooo much casuality the slip ring side was the opposite to the one running to the + field, because I think it could be shorted being a straight conection, with no resistance due the winding coils
There was a vendor on ebay selling those slip rings quite ago. If still, the slip ring can be changed by yourself
Last edited by NachoRT74; 01/07/18 11:03 AM.
With a Charger born in Chrysler assembly plant in Valencia, Venezuela
|
|
|
Re: Overcharging, even with field wire off. Whats up with this?
[Re: NachoRT74]
#2430438
01/07/18 12:45 PM
01/07/18 12:45 PM
|
Joined: Nov 2003
Posts: 36,040 Lincoln Nebraska
RapidRobert
Circle Track
|
Circle Track
Joined: Nov 2003
Posts: 36,040
Lincoln Nebraska
|
its a good thing that the downstream side of the alt field circuit shorted as opposed to the input (blue wire side) shorting, so that it full fielded (which is bad enough) as opposed to a dead short going back to the fusible link.
live every 24 hour block of time like it's your last day on earth
|
|
|
Re: Overcharging, even with field wire off. Whats up with this?
[Re: John_Kunkel]
#2431546
01/09/18 12:40 PM
01/09/18 12:40 PM
|
Joined: Jan 2003
Posts: 27,421 Balt. Md
383man
Too Many Posts
|
Too Many Posts
Joined: Jan 2003
Posts: 27,421
Balt. Md
|
If the blue field was shorted to ground you'd have a smoking wire, if the green field was shorted to ground you'd have maximum voltage output.
That's right as my buddies 71 Roadrunner had the alt rotor short to ground right after the brush fed by the blue 12 volt ign voltage and burnt his fuseable link out and started to melt some wires. I had to replace the alt and fuseable link and repair some wires on it. Ron
|
|
|
Re: Overcharging, even with field wire off. Whats up with this?
[Re: 383man]
#2431678
01/09/18 04:17 PM
01/09/18 04:17 PM
|
Joined: Aug 2007
Posts: 6,095 Valencia, España
NachoRT74
master
|
master
Joined: Aug 2007
Posts: 6,095
Valencia, España
|
If the blue field was shorted to ground you'd have a smoking wire, if the green field was shorted to ground you'd have maximum voltage output.
That's right as my buddies 71 Roadrunner had the alt rotor short to ground right after the brush fed by the blue 12 volt ign voltage and burnt his fuseable link out and started to melt some wires. I had to replace the alt and fuseable link and repair some wires on it. Ron That's why I told it got luck there. If wires were conected the other way around ( which is posible without any problem since they work in both positions the same ), the short was to happen just turning on the ign 1
With a Charger born in Chrysler assembly plant in Valencia, Venezuela
|
|
|
|
|