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Charge Wire Change Motorola Alternator |
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billd 
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Forum Administrator Joined: Jun/27/2007 Location: Iowa Status: Offline Points: 30894 |
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 Posted: Sep/08/2011 at 10:55am |
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Yeah, I'd put an additional ground from the block to the chassis. I know they ground that wire to the cross-member, however, I've seen enough rust between crossmember and chassis itself to cause issues, too.
The regulator grounds to the alternator itself, (thus the black wire in the connector), rather than through the case to the car......... that's to keep the regulator and alternator on the exact same ground. (prevents the regulator ground being better or worse than the alternator ground if they both use the same ground) Dave - depending on your wiring - no bulb for AMC past about 1967 is excited by ignition yellow wire. It takes only a good off-idle speed to get them to start...... less than your stall speed (if running an automatic) I'd bet. |
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gwryder
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Joined: Jun/30/2009 Location: Michigan Status: Offline Points: 710 |
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Posted: Sep/08/2011 at 6:20pm |
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Looking back at the first post with the problem of too low charging voltage at the battery @ 2000 rpm. If the battery is in a low state of charge, then the voltage will not be at the spec of 13.7. Before checking the voltage across the battery make sure the battery is fully charged. If you can access the electrolyte by removing the battery caps, check the specific gravity with a hydrometer.They are cheap. If the S.G is 1.27 then it's fully charged and the voltage read at the battery with the engine running at 2000 is valid. If the S.G is lower, the voltage at the battery will be lower. Maybe there's not a problem with the cabling. If you can't get to the electrolyte, then check the Terminal Voltage. Ref this link http://en.wikipedia.org/wiki/Automotive_battery#Terminal_voltage
If the S.G. indicates fully charged and the charging voltage is still low, then
try checking voltage drops across each cable, connections at studs, etc, using the most sensitive range on the voltmeter. If any voltage registers, then there's a resistance. Resistance restricts current flow creating the voltage drop. Remember current must be flowing to do this.
Somewhere you're going to find a large drop. The problem might be many poor connections, internally corroded cables accumulating resistance. I guess call it voltage drop stacking. If cables are too small gage, a drop will show up. It may be small, .1 volt drop with 5 amps flowing is sRemember, that current must be flowing to read the drops.
Again, Good Luck. It's impressive all the posts on this one.
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John
70 AMX |
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billd
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Posted: Sep/08/2011 at 9:58pm |
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John good point that I missed....... true. Can only really check with a GOOD fully charged battery.....
Battery problem can lead to low voltage, low battery can as well.
Motorola spec is 13.9 - 14.7 depending on ambient temp - the voltage regulator is placed next to the battery so that it can tell what the battery temp is. A cold battery needs higher charging voltage, so a Motorola regulator will regulat at "about" 14.7 when cold, and drop down to the low 14s to high 13s when the battery or regulator temp is warm - under hood temp that is. There's a thermistor in the regulator. They assume the regulator will be at or near the same temp as the battery being just inches apart.
I always make sure the alternator is checked with a cold regulator when I test. I also use a rheostat to full-field them to check full charging current and voltages, etc. Typically the Motorola regs I have do regulate to about 14.5-14.7 when I first start the testing.
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FuzzFace2
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Joined: Jul/05/2007 Location: Angier, N.C. Status: Offline Points: 10356 |
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Posted: Sep/08/2011 at 10:59pm |
The drag (70 Javelin) car wiring is all run by me, only thing stock I am using is the ALT & REG. I have brought the RPM up to 3000 in the pits and it would still not charge only after a run of 6000 shifts/lights would the volt meter read 14+ volts. Oh I dont think I ran a "excite" wire as I am running a full MSD IGN setup. I have ot pull out my wiring dia. I made before wiring the car.
Sorry for the hi jack.
Dave ----
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TSM = Technical Service Manual
75 Gremlin X v8 for sale 70 Javelin 360/auto drag car 70 Javelin 360/T5 Street car |
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FuzzFace2
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Joined: Jul/05/2007 Location: Angier, N.C. Status: Offline Points: 10356 |
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Posted: Sep/08/2011 at 11:07pm |
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I was just thinking of my setup the output of the ALT goes all the way back (think 10 ga wire) to the batt before the NHRA batt cut off switch so it would work as it should. I pick up power to the other devices from the SOL switch that is still under the hood. Again I would need to check my prints to see just how I did this over 15 years ago.
Dave ---- Edited by FuzzFace2 - Sep/08/2011 at 11:08pm |
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TSM = Technical Service Manual
75 Gremlin X v8 for sale 70 Javelin 360/auto drag car 70 Javelin 360/T5 Street car |
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PHAT69AMX
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Posted: Sep/08/2011 at 11:16pm |
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--------------------
MAD Electrical Is the MAD Electrical web site down or gone ? Unable to get that page to come up on my pc...... --------------------
Yes billd, agree, definitely want a Fusible Link or Fuse of some kind.
And that a car's Alternator is not meant to charge a low car battery. Appears my system is not properly sensing load and increasing output. On a GM doesn't the Alternator Output Wire go directly to the Battery ? Unlike a 3-Wire Delco Alternator with Remote Sensing, The Motorola "senses" at the Alternator Output Post Trying to understand the ALT Light circuit and function. At one end the Isolation Diode is between the two ends Alternator Voltage exists on the Alternator Side of the Isolation Diode. If System Load increases, Alternator Voltage drops The Regulator sees the reduced Alternator Voltage Reckon this is why downstream system resistance Figure there's gotta be a reason the ALT output --------------------------------------------- Have yet to remove the Block Ground and clean connections. FF2, gwryder, Wonder if I'm chasing a mirage, its just a shot Optima Battery ? -------------------------- Thanks everyone for all the help. -------------------------- Made a version of the Charging System Diagram from the '69 TSM.  |
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billd
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Posted: Sep/09/2011 at 6:07am |
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I don't consider that a hi-jack Dave - it's info related to the issues of the OP, and info onlookers might find useful when reading phat's thread. These DO get really interesting and all of us cna learn something. I guess I TOTALLY spaced out on your car being what it is - no stock ignition, DUH, sorry.
running late in my self-imposed schedule headed to Cordova - thought I'd sneak in one post while eating some skimpy breakfast.
Maybe more later as I get access, time, etc. Ya know this phat character is pretty clever - with the sharp-minded help he's getting here, I'm sure all will end up fine.
If I can be of assist when I return............................... Edited by billd - Sep/09/2011 at 6:09am |
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PHAT69AMX
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Posted: Sep/09/2011 at 1:20pm |
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Ah, FF2, on your Javelin, the Alternator Output goes all the way back to the Battery ?
Ok, was wondering if anyone had done it that way.
Is there a Fusible Link between the Alt Output and Battery ?
Or is there just the Fusible Link between the Solenoid Post
where the "+" Battery Post attaches and the Main Wiring Harness
that gets it's power from the same Solenoid Post ?
Using a Delco or a Motorola Alternator ?
In the first (2) diagrams was trying to show that.
Original wiring has the Alt Output also "behind" the Fusible Link
at the Solenoid Post where the "+" Battery Cable connects.
If the Alt Output is moved to attach at the Battery
it is then "in front of" the Fusible Link, but Main Harness and other loads
are still "behind" the Fusible Link mounted to the Solenoid post.
Thanks everyone.
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FuzzFace2
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Joined: Jul/05/2007 Location: Angier, N.C. Status: Offline Points: 10356 |
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Posted: Sep/09/2011 at 3:43pm |
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Funny thing my drag car uses the stock Motorola setup, my street Javelin has the Delco installed by a PO. This is the drag car I am talking about, I hate to say this but the line from ALT to the batt in the trunk is not fussed and I am asking for trouble. Dont do as I do type thing! It was the only way I knew of charging the batt and still have the batt kill switch work right. If I ran the output to the SOL (stock location) the ALT would supply power to the IGN system as that is where it gets it power from and stayed running with the switch off. I also use the stock fuse panel to supply power to anything else like gauge lights, elect. Fuel pump, etc. I cant remember if there is a fuse link at the SOL to feed the stock panel but thinking no. Should look into fusing both someday I guess? Looking a the last diagram are you sure the ALT light wire picks up the ALT output before the diode then on to the light etc? I will have to check my 70 TSM to see if it is the same? Oh wait that is how the light get power from the other side to cancel the light! I have to check over the TSM and wiring dia. This weekend for my gauge install in the street car so I will look up the drag car Dia I have to see if different than I said here. Dave ---- |
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TSM = Technical Service Manual
75 Gremlin X v8 for sale 70 Javelin 360/auto drag car 70 Javelin 360/T5 Street car |
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PHAT69AMX
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Posted: Sep/10/2011 at 1:07am |
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Haven't taken an Motorola Alternator apart. Going by text and a wiring diagram in the '69 TSM, reckon the Orange Wire Regulator Terminal lead is attached to the Alternator Output Termianl behind the Isolation Diode on the Alternator side.
Text also states this is also the Sensing Voltage source. To me this says the Motorola Alternator is like a 1-Wire Delco Alternator. Neither have "Remote Sensing" like a Delco 3-Wire Alternator which is reccommended on the MAD Electrical web site.
Going on what was read on the MAD Electrical web site when it was online, Sensing at the Alternator is less "desirebale" than Remote Sensing and more "sesitive" or less "responsive", or "compensating" to downstream system resistance, if I understand correctly. From the 1969 AMC TSM page 4-4 "The Alternator Charging Circuit" "As the Alternator starts to provide Voltage, the Output Voltage will develop at the Regulator Terminal (Orange Wire)."
"When the Alternator is started, the voltage at the Alternator Regulator Terminal (Orange Wire) is used to supply the Rotor (Field) excitation current; this voltage is also used as the SENSING VOLTAGE to operate the Voltage Regulating System."
On the same page is Figure 9 - Wiring Diagram. In Figure 9 is where it shows the Orange Wire Regulator Terminal lead attached to the Output Termianl behind the Isolation Diode on the Alternator side. Figure 9 is re-created and posted in this thread, with a few "refinements" per the full Wiring Schematic found in the back of the TSM and as pointed out by billd in some posts some time back. Edited by PHAT69AMX - Sep/10/2011 at 1:09am |
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billd wrote: