A 12 volt draw on battery from a one wire alternator

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Majestic

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Mechanic swapped my alternator to a one wire during a engine swap. Now the car is eating batteries left and right. Still charges at 14 but just checked draw on negative cables and had 12 volts. Disconnected alt. And draw went to 1.3. I'm new on working on cars so any help is appreciated and you may have to explain things. I'm not sure what some stuff is.
 
First, how are checking the drain? Are you using a multimeter from the negative cable to the negative post when they are disconnected? You should be measuring current in amps, not volts. Any drain over 500 milliamperes will drain a battery overnight. Check the drain in that manner, and then remove fuses one at a time to isolate the circuit causing the drain. That should get you started. There are a couple circuits that are not controlled by the fuses, but start with the fused ones first, as they are easier to remove. Having the proper diagram will also help. If you do not have one, I am certain someone will chime in.
 
You need to check the amperage of the draw. Not sure how you were checking it. You'll need to put an ammeter inline between the negative terminal of the battery and the negative cable. Anything over .050 amps is too much. If you have more than that you can start pulling fuses and then disconnecting connectors until the draw amount drops. You should use an ammeter that is fused incase it is a large draw so you don't burn up your meter.
 
BE CAREFUL checking current with a multimeter. Flukes have relatively expensive fuses, some of the inexpensive "Horrid Freight" have no fuses at all. The current measuring setup is a DIRECT SHORT between the probes, which means if you get that ACROSS 12V to round, "smoke will happen."

I would start like so:

Disconnect the battery for safety, the GROUND

Start by putting your 12V test lamp in SERIES between engine block and battery post. If it lights up fairly bright, you might have a fairly large draw and might damage your meter

Start with that, and post the model no. of your meter, we can step you through this
 
Even the OEM alternator would do that when shorted internally. So maybe you have a bad alternator installed?
 
Decided to buy a new alternator. Does the voltage regulator on firewall need to be hooked up again since going with a 2 wire?
 
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That "little box" attached to the Mopar alternator appears to be an aftermarket regulator, you need to find out what that is. Some of them, maybe all are a "one wire" setup.

You should be able to unhook the big black wire from the big stud at the alternator and "stop" the draw. That will confirm where it's coming form

No, you do not want your original regulator hooked up if that is the case

I DO NOT BELIEVE you can easily adapt that little regulator to a standard mopar alternator, which means you must reconnect your regulator. There should be a black rubber connector for it unless someone cut it off

The Mopar alternator has a green and a blue "push on" connects to the two field wires. Does not matter which one. The big black with eyelet goes to the big output stud.

You likely have more problems in the wiring
 
I suppose by now you've noticed both alternators are the same OEM correct Square back alternator. Difference being one of them has a aftermarket regulator tagged onto the back of it. I don't know how your mechanic wired this but if not right it wont work. Originally, the blue wire should power the regulator and the field but only at switch on.
I see a added red hot at all times going to that regulator and one of the field terminals. Don't know where that blue wire disappears to or how the heck that works, BUT.... Since the following is pretty much how older GM charging systems are upgraded, There is possibly a place where your mechanic jumpered/tied the OEM blue and green together. In the GMs that was done with a short jumper with 2 male spades at their OEM regulators harness connector. That jumped only 2 of the 3 or 4 wires ( I forget ) at their regulator. Anyway... Check your blue and green all the way back to the OEM regulator before you plug it in. Make sure that regulator is well grounded at it mounting bolts. Hook it all up and check that your current draw is gone. Start it up and check for regulated output.
 
Thanks I have not found anything yet. Was overcharging and now I had alternator bench tested and was putting out 15 volts. Put it back on car and not charging the battery according to advanced. Car running only off battery. I've about pulled all my hair out with this thing. Wiring seems to be right. I bought a new regulator but did a test the manufacturer said to unplug regulator and run jumper from field wire to negative post and start car. If not showing charge it said not to hook up regulator. Should I change the ballast? Any ideas
 
You need to learn to troubleshoot this ON THE CAR. Forget what the parts stores say. So let's do this. If you get lost, come back with questions.

1.......I assume you now have the old Mopar system hooked up and the "one wire" add on deal is gone?

2......Go to MyMopar.com if you have not and download a service manual for your car free. Some of them there came from guys here

3......While there, download the aftermarket wiring diagrams. These are sometimes easlier to follow but ARE NOT factory and sometimes leave out details.

4.....Give us some photos of what you now have hooked up in the car

5......If 4 is "yes" let's get to troubleshooting..........

6.....FIRST let's see if voltages are reasonable..........

A.........With key on/ engine stopped, the blue field wire at the alternator should have close to "same as battery." This is with ALL WIRING CONNECTED "normal."

B.........Green field wire should be quite low, 1, 2, 3V. Regulator MUST BE GROUNDED. Remove it, scrape around the bolt holes, and mount tight with star lock washers.

C........With all wiring connected, put one probe on blue wire at alternator field. Stab other probe into top of POSITIVE battery post. You should read VERY LITTLE voltage, and the less the better. More than .3V (3/10 of one volt) means there is a voltage drop problem in the harness/ bulkhead connector/ ammeter/ ignition switch. More on that later

D........Make sure battery is reasonably fully charged, preferably with a regulated charger overnight.

E.......Run engine, warm up, let battery "normalize" and measure battery voltage at fast idle/ simulated low/ medium cruise RPM. Voltage should be 13.8--14.2

IF NOT........

F.......If battery voltage is quite low, 12, 11V, measure voltage "running fast" at alternator stud. If voltage is same low reading as at battery, system is NOT charging.

G.......If system is not charging, remove GREEN field wire at alternator, and ground that now exposed alternator terminal with a alligator clip lead. With key "in run" a spark should be seen. This shows field is drawing current, is good. Run engine RPM up slowly watching ammeter or voltmeter. Voltage should begin to rise. IF NOT check alternator field current. READ THE SERVICE MANUAL it tells how in there. Also, with your alligator clip grounding the field, measure voltage, with "key in run" at the blue field. This voltage should be "same as battery." If this is true, alternator is likely bad.

H..........When you grounded alternator field, and IF alternator now charged, trouble is in field circuit/ VR. Hook back up normal. Remove VR connector. Work it in/ out several times to scrub the connections clean, and visually inspect. Now "rig" a couple of machine screws so you can JUMPER the two VR connections together.
Now remove alternator field BLUE wire and alligator clip that exposed alternator terminal to ground. With key in "run" a spark should be seen. Run engine up slowly in RPM. Battery voltage should climb up. This shows field wiring is OK. If this happens, replace the VR. Again, it MUST be grounded.

You can fix this..........these are easy
 
Thanks for the advice and sorry been working so just now getting a little time to tinker. I'm not sure on alternator which field wire goes where. I have the green and blue field wires. I have swapped them and shows nothing different. Alt. is reading same as battery. I checked all other wiring. Is a single ballast resistor ok with electronic ignition? The bulkhead wiring there was some not so tight connections. I don't think that's my problem though. I don't think alt. is charging even though advanced says it was putting out 15 volts. I will post some picks in a few.
 
I'm not sure on alternator which field wire goes where. I have the green and blue field wires. I have swapped them and shows nothing different. .

Does not matter which field connection goes to which wire, electrically

Alt. is reading same as battery. .

You must be specific. If you mean alternator is reading same as battery WHEN RUNNING, and also that the voltage is quite lower than 14 when IDLING FAST, then it is not charging

Is a single ballast resistor ok with electronic ignition? The bulkhead wiring there was some not so tight connections. I don't think that's my problem though.

Single ballast is fine IF you are sure you have a later model ECU, whichs is known as "4 terminal" whether ECU has 5 physical terminals or not. Engine will not run if you have an older 5 terminal ECU with a 2terminal ballast

Bulkhead connector can be a HUGE problem. Please read the MAD article if you have not...........

Catalog

The VR power is fed off same wire as ignition "run" so if that was dead it would not run.

I don't think alt. is charging even though advanced says it was putting out 15 volts. I will post some picks in a few.

The parts store test does not mean much of anything. You need to learn to test this on the car. Follow steps I gave you above The "quick" steps for a completely non charging alternator is..........Remove the green field wire and jumper that alternator terminal to ground. Turn the key to "run". Verify you have battery voltage at the blue field wire WHILE STILL connected. You should be able to disconnect / reconnect your jumper wire and see a small spark in subdued lighting.

Now start the car, slowly bring up RPM and watch voltmeter hooked to battery. Battery voltage should start to rise with RPM, if the alternator is healthy and the battery is not very dead, it should come up above 13.5. Don't allow it to rise much above 16 --17V
 
If i was you i would deal with one problem at a time,get your charging sorted out, then move on to ignition. Mr 67dart273 has explained everything in detail,something that took a great deal of time and thought. If this is above your pay scale maybe there is someone that can help you sort it out. Guy that set up the one wire deal overlooked something, and for all the trouble now,returning to stock seems the best plan.

The two spade (brush)terminals can be connected either way.
 
Does not matter which field connection goes to which wire, electrically



You must be specific. If you mean alternator is reading same as battery WHEN RUNNING, and also that the voltage is quite lower than 14 when IDLING FAST, then it is not charging



Single ballast is fine IF you are sure you have a later model ECU, whichs is known as "4 terminal" whether ECU has 5 physical terminals or not. Engine will not run if you have an older 5 terminal ECU with a 2terminal ballast

Bulkhead connector can be a HUGE problem. Please read the MAD article if you have not...........

Catalog

The VR power is fed off same wire as ignition "run" so if that was dead it would not run.



The parts store test does not mean much of anything. You need to learn to test this on the car. Follow steps I gave you above The "quick" steps for a completely non charging alternator is..........Remove the green field wire and jumper that alternator terminal to ground. Turn the key to "run". Verify you have battery voltage at the blue field wire WHILE STILL connected. You should be able to disconnect / reconnect your jumper wire and see a small spark in subdued lighting.

Now start the car, slowly bring up RPM and watch voltmeter hooked to battery. Battery voltage should start to rise with RPM, if the alternator is healthy and the battery is not very dead, it should come up above 13.5. Don't allow it to rise much above 16 --17V
 
I did everything you said. No spark on either terminal. I think its a bad alternator. Just to make sure I got it right. The green wire goes on either field terminal and runs over to voltage regulator. The blue wire hooks to the other field terminal and runs over to center pin on the VR. I read the MAD article over and over and actually bought some wiring for it. Would it be right if I mounted my VR next to Alt. Do I still need ballast and will the regulator work with it going straight to starter relay?
 
If i was you i would deal with one problem at a time,get your charging sorted out, then move on to ignition. Mr 67dart273 has explained everything in detail,something that took a great deal of time and thought. If this is above your pay scale maybe there is someone that can help you sort it out. Guy that set up the one wire deal overlooked something, and for all the trouble now,returning to stock seems the best plan.

The two spade (brush)terminals can be connected either way.

I really appreciate 67dart273's help. It probably is above my pay grade but I ain't giving up. Spent to much money on this with 3 different mechanics and none of them solved my problem. So now its gonna take me some time but I'm learning about my car in the process.
 
You need to fix this before you start making mods, or pretty soon you will be in a REAL fix and I can't help you.

Let's go over this again:

1.........The alternator field is a MAGNET (electromagnet) When you feed battery power into one field terminal and ground the other you are activating that magnet. You need to make certain it is getting power and DRAWING CURRENT. This shows the field is good, and that the brushes are making contact and carrying current.

2....So........basics........take an "alligator clip" wire and hook to a battery source such as the starter relay large stud, and connect that to either alternator field terminal (blue and green hanging loose, disconnected)

3....Now take a second alligator lead and connect to the remaining alternator field terminal. You should see a small spark in subdued/ shaded light when you connect/ disconnect that wire. If you cannot see it hook your multimeter up to measure CURRENT

PLEASE POST a photo and or brand / model of your multimeter so we can help you hook this up.

Next, jumper one lead of the multimeter to ground, hook the other lead to the alternator field which DOES NOT have the battery jumper connected

The circuit should look like:

From starter relay big stud (battery)..........clip lead.........to one alternator field terminal.........through alternator field........other alternator field connected to one lead of multimeter in CURRENT mode.............remaining lead of multimeter grounded.

You should read more than 3A as much as maybe 4 or 5, and not more than 6A. Loosen the belt and turn the pulley on alternator to see if this varies
 
Next: If the test above showed the alternator field was indeed drawing some current, Hook the belt back up, leave your battery clip lead hooked to the one field terminal, and remove the hookup to the remaining field terminal.

REconnect your remaining clip lead to the remaining field, and ground that terminal. Now restart the engine, and monitoring battery voltage, again look for rising voltage. If the voltage at battery remains down around 12V or even less, Move your meter (volts) to the alternator output stud. See what that reads, at a good fast idle.

If it ALSO reads quite low, 12V or less, the alternator is simply NOT charging.

But if it reads quite HIGH perhaps 17--20V this means that you have a break/ bad connection in the charging wire path to the battery
 
Notice that in my last two posts we were connecting the field direct to battery and ground. This ELIMINATES a whole bunch of wiring problems and the VR. If the alternator will not charge when excited in this way (also called "full field") then it either is

1 bad alternator
2..badly slipping belt
3..a break in the charging wire from alternator........through bulkhead....through ammeter circuit.....back out bulkhead.......to battery
That is why we look at voltage on alternator output stud

Also more on measuring alternator field current is in section 8 of your factory shop manual. Again, you can download these free, from MyMopar. No, LOL, I don't work there, but several manuals there got there because of the guys on here
 
Next: If the test above showed the alternator field was indeed drawing some current, Hook the belt back up, leave your battery clip lead hooked to the one field terminal, and remove the hookup to the remaining field terminal.

REconnect your remaining clip lead to the remaining field, and ground that terminal. Now restart the engine, and monitoring battery voltage, again look for rising voltage. If the voltage at battery remains down around 12V or even less, Move your meter (volts) to the alternator output stud. See what that reads, at a good fast idle.

If it ALSO reads quite low, 12V or less, the alternator is simply NOT charging.

But if it reads quite HIGH perhaps 17--20V this means that you have a break/ bad connection in the charging wire path to the battery
 
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