Farmall M overcharging

This is my first time posting a message. Ive solved many of my previous problems via searching the archives... so thank you to all who contribute, but this one has me stumped. 1953 Super M converted to 12 volts over a year ago according to Bob M's instructions, with a new alternator and new wiring. The tractor ran and charged perfectly...until last week. I noticed my ammeter pegged on the postive side. The needle never returned to "0" and the battery was starting to boil over. Using a multitester I got 15.5 volts at the battery with the tractor running. Got the battery load tested and it came back good. I assumed that the voltage regulator failed. I changed the regulator out, had the alternator tested, and that too came back good. When I put the alternator back on the tractor, it's still boiling the battery and pegging the ammeter. I also have around a -9 amp draw on the ammeter when I pull the ignition switch out without the tractor running, which seems kinda high. It used to only be 3-4 amps. Starts and runs fine, but just pegs the meter and boils over the battery, even at an idle. I did replace the points and set them at .020. It has an upright delco distributor. If I disconnect the + side of the coil, the amp draw drops back to 3-4 amps. Could the amp draw be linked to the alternator overcharging... trying to compensate for the draw? Any ideas would be greatly appreciated. Thank you for your help and for your previous responses to other posts. Without them, my tractor would probably be permanent a lawn ornament.

I forgot to add, the alternator is a delco 10si, 3 wire setup. Thanks again.

Sounds like there is an open wire to the #2--battery voltage sensing terminal on the alternators regulator. It can't read the battery's voltage & assumes that the battery needs full charging current/ voltage. Try connecting a jumper wire from the positive terminal of the battery to the #2 terminal of the regulator while engine is running. This is the right-hand terminal as viewed from the rear of the alternator. If charging returns to normal, the problem has been found. If no change after this test, try a jumper from the negative battery post to the alternator frame. Let us know what the results are.

I agree, a faulty crimp or spade terminal can do it. JimN

More than likely it is caused by a poor connection at or feeding #2 terminal as other posters have stated. Just to add some things here, several years ago when the internal electronic voltage regulators were new to the ag field, I did some expermenting with alternators on the test stand, by inserting a potentiometer in series to the #2 termanal I was able to simulate poor connections by varying the resistance and the voltage would rise to over 18volts. When these connectors on the alternator are exposed to operating conditions and weather, a little rust and corrosion can really drive that regulator crazy.Good reason to put something on connector to seal it. (vasoline or grease works) On another note, about two years ago a supplier of alternators and parts had a bad batch of parts from some where (china) and these alternators were cooking batterys like crazy. Last year I put a rebuilt 15 SI on for a guy and shortly after it was pegging the volt meter, after checking connections I installed a new regulator, better but not good, another new regulator from a different supplier, still not right. Put on a spare alternator I have worked perfect. As we all know the regulator controls the current flowing through the rotor to control output so I replaced the rotor, still no gf course, every time I took it apart I double checked diode trio , bridge and stator. Got him a different alternator, and it is working fine. Some times you just have to give it up. If the alternator in question was put through all the tests on a test bench it should be fine (of course, I have no way of knowing what tests were performed) so we come back to connections.

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Does your alternator conversion use a diode in the #1 excite wire to the alternator ? If so then they will draw about 3-7 amps to excite the alternator plus another 4 plus amps for the ignition coil, so 9 amps draw when you tuen on the ignition is about normal.
If your alternator conversion uses a resistor or charge indicator light instead of a diode, they will limit the alternator excite current to about 1/2 - 1 amp

As others have stated, the overcharge is likely related to a bad connection in the #2 sense wire to the alternator plug.
Do you have the #2 wire in the alternator plug connected to the big "BAT" stud on the alternator rear ? That is a good place for the regulator to sense system voltage and adjust alternator output to about 14.5 volts. Many regulators on Delco 10 SI alternators are set at 14.6-8 volts,anything under 15 volts is OK.

For some unknown reason,the blade connections on most of those regulators are unplated steel and will rust if exposed to weather. Make sure the plug and regulator blades are free of corrosion, and coated with electrical grease to protect them.

Jon, I respectfully disagree on the Amps running through the excite terminal. The amps must flow through the idiot light, and there are no idiot lights that will pass any where near those numbers. JimN

If there is a 9 Amp draw with the tractor not running, that sounds like a short circuit somewhere to me.

Normal field exciting current could very well run 3 or 4 amps like said if using a diode and not a resistor. I would very much doubt if a tellite is used in this conversion application. Electrical grease is great, if you have it. The factory used to put some of their favorite formula in these connectors and you couldn't get the darn things apart, so just some plain old vaseline, it will stay in there very well and isn't conductive. (at these voltages)

"Does your alternator conversion use a diode in the #1 excite wire to the alternator ? If so then they will draw about 3-7 amps to excite the alternator plus another 4 plus amps for the ignition coil, so 9 amps draw when you tuen on the ignition is about normal.
If your alternator conversion uses a resistor or charge indicator light instead of a diode, they will limit the alternator excite current to about 1/2 - 1 amp"

How much am I off ? Like I said, the field circuit when direct wired through a diode will flow 3-7 amps, but only 1/2 - 1 amp with an indicator light inline. Am I really too low at 1/2 amp ? I have never actually put an ammeter on one to measure it. I know that in the 70's, some of the GM veichles had two indicator lights wired in parallel for a little faster alternator excite. They called the second one the "hidden indicator light", as it was hidden in the instrument cluster and did not shine through the GEN or ALT indicator window. This dual bulb setup bumfoosled some mechanics trying to fix a slow to excite alternator. They did not realize that there was another hidden light in there that was burned out and caused the slow alt excite.

Sorry, I intended to say " Am I really too high at 1/2 amp"?

First off, thank you so much for all the replies. I never expected so many people to respond. Before I get into detail, please understand, I have a 4yr old daughter and a 8 1/2 month pregnant wife, so my time in the shop is very limited, and I was"nt able to dig real deep into my problems.
Ok, as of today I installed a new 12 INTERNALLY ballated coil. Points are new, and gapped correctly at .020, along with new condenser. I did eliminate the external ballast resistor when I added the new coil.
Alternator and battery check out as stated in my last post, although I"m beginning to question my battery. (Ill have it load tested again)
Per Brownie 450 I ran a jumper wire from the number 2 "sense post" from the alternator directly to the positive battery post. I grounded the alternator case to the negative battery cable. I also replaced the plug that plugs into the number 1 and 2 alternator posts with spade terminals to ensure that corrosion was"nt causing the problem. I do have a diode in the #1 exciter wire, facing the right direction. The engine quits when I push in the ignition switch. At idle the ammeter is reading 0 amps (no lights), and once the throttle is pulled (even just a little bit, less than 1/4 throttle) the ammeter gets pegged. Now the difference from my last post IS, NO battery boil over. With the jumper wires hooked per Brownie 450"s instructions the ammeter is still pegged, but the battery never boiled, with the tractor running at various rpm"s from idle to WOT for about 15-20 minutes. Could the ammeter be shot? Ive never seen one go bad in my 29 years, but my experience and knowledge is far limited as compared to most whom reply on this site. The tractor runs great, it"s just pegging the meter now, and it does have a draw.
With the points closed, ignition on, engine off, I"m seeing a 9-11 amp draw on the ammeter. Points open 3-4 amp draw on the meter. New coil, points, and condensor... and 1 year old wires. Unfortunately between my 4yr old daughter and my justifiably frustrated pregnant wife, I was unable to use a multi-tester or test light on anything. Hopefully tommorrow I"ll be able to. The tractor runs great, and all lights work normal, I appreciate any and all opinions and ideas. Thank you in advance.
Also, I realize I am new to the forum, but I wanted to share that as of today I acquired a farmall straight A. The tractor means alot to me not because it"s an A, but because it was my grandfathers. It was sold a while ago, and fortunately I was able to get it back. A friend through a friend through a friend type of thing. It runs, but needs a little work. My wife thinks it"s "cute" cause it"s pink. Not painted pink, pink from the sun fading the IH red. Anyway thanks again for suggestions and replies.

If the shunt in the amp meter is thinning from age or corrosion, it will pass more current to the needle, and make both charging, and draw current read high. A amp meter that has run pegged for a while will possibly be heated from over current to the point that the shunt night thin. At any rate, Using a different gauge might determine the truth.
Bat voltage under high idle, charged battery, no lights on, should be 14.2 to 14.5 volts. If so it is OK. Congratulations on the A, and your expectation of birth. JimN

I usually use a resistor of 10 ohms--20 watts on the #1 terminal [turn on] to the alternator. At 12 volts, this works out to less than 2 amps draw for the turn-on current. I've never had a heating problem with any resistors used on conversions which I have done. I'm trying to guess where the extra current is going????
If you could unhook the heavy Bat. wire from the back of the alternator & then pull out the ignition switch to see what kind of current you are drawing then. Also, if you have access to a "hold against" ammeter, see what it has to say. Also, if possible, use an analog meter instead of a digital. The regulator is a high frequency device & will cause a digital meter to read incorrectly.
I'm wondering if 1 of the rectifiers in the bridge at the back of the alternator is shorted.
Jim N. has a valid point mentioning that the ammater might have been over-stressed & is reading incorrectly. A hold-against ammeter will prove this out.

Just re-reading this whole thing---how much output is your alternator rated at? The amps rating is usually stamped on the case near the tightener hole. See if you can read this value. I always use an alternator rated 37 amps on tractor conversions--but are hard to find now. If your unit is a higher capacity unit, say 63 amps or more, & you are using the original meter, the meter would be reading maximum. Pulley size will affect output also, but not to that large a degree---our SMTA will charge off scale right after starting if not left at idle, but will taper back to less than 5 amps within 1 minute after a "normal" start.
Getting back to this 7 amp discharge thing, try unhooking the wire at the coil as well as the Bat. terminal at the back of the alternator--then pull the ignition switch on & see what happens.
If you don't have a hold-against ammeter--do you have a spare ammeter which you can use after disconnecting the coil & alternator we need to know where the 7 amp draw is getting away to. We have to isolate between the alt. & coil.

The alternator is a 63 amp. Between work, wife and kid, I havent gotten into anything else yet. I did start it again today. I guess I was hoping it would somehow cure itself. I need to get some readings on the battery. Ill let you know as soon as I do. Time is something I can"t seem to find enough of lately. By the ammeter, it kind of appears that the alternator is spinning too fast. This new one does have a little smaller pulley, but the tractor only turns 1600 rpms.
With the amp draw, I think its in the distributor... a short or arcing maybe in the screw that runs through the side to the points. I did pull the coil wire off, and the draw goes away, coil was replaced too.
I also unhooked the negative battery cable and clipped the test light to the cable, while touching the negative battery post. Nothing with the switch off, but pull the ignition switch the test light glows. Should the test light remain out in both the on-off position of the ignition switch? Or just in the off postion? Thinking the short was coming from the points, I rotated the engine allowing the points to open and close, and the light stayed on either way. But with the ignition switch off I"m good, nothing on the test light. Only with the ignition switch. Basically when doing a test like this, shouldn"t the test light stay off no matter what the ignition switch is doing? Otherwise there is a definate short?
Thanks for all the help, and your patience. I wish I knew half as much as you guys.
Janicholson, thanks for the tip on the meter, I"ll probably get a new one mainly because the one in it is original and hard to read due to past moisture.

The alternator is a 63 amp. Between work, wife and kid, I havent gotten into anything else yet. I did start it again today. I guess I was hoping it would somehow cure itself. I need to get some readings on the battery. Ill let you know as soon as I do. Time is something I can"t seem to find enough of lately. By the ammeter, it kind of appears that the alternator is spinning too fast. This new one does have a little smaller pulley, but the tractor only turns 1600 rpms.
With the amp draw, I think its in the distributor... a short or arcing maybe in the screw that runs through the side to the points. I did pull the coil wire off, and the draw goes away, coil was replaced too.
I also unhooked the negative battery cable and clipped the test light to the cable, while touching the negative battery post. Nothing with the switch off, but pull the ignition switch the test light glows. Should the test light remain out in both the on-off position of the ignition switch? Or just in the off postion? Thinking the short was coming from the points, I rotated the engine allowing the points to open and close, and the light stayed on either way. But with the ignition switch off I"m good, nothing on the test light. Only with the ignition switch on. Basically when doing a test like this, shouldn"t the test light stay off no matter what the ignition switch is doing? Otherwise there is a definate short?
Thanks for all the help, and your patience. I wish I knew half as much as you guys.
Janicholson, thanks for the tip on the meter, I"ll probably get a new one mainly because the one in it is original and hard to read due to past moisture.

Reading your original post, you said you replaced the points but not the condenser in the distributor. Since the tractor runs well, we can probably eliminate the cond. for now. However, have a good look in the distributor for any place the incoming wire could be up against a ground--including the condenser lead.
When you have the coil & alternator Bat. wire disconnected, pull the 2 regulator wires as well & see what the amp draw is then. On one of these old tractors, there is only 3 electrical areas---ignition, charging, & lights which can be causing your problem. We have to know which one is at fault.
By the way, take care of the family first. The tractor will still be waiting.

Do not worry about excess RPM, it came out of a car with 3 or 4 times the RPM, and alternators like these are self limiting on output amps. The issue is where the amps are going when the ignition is turned on. I would not change anything until a different good amp gauge was installed. Knowing the real numbers is important in this case.
The light bulb test you describe is normal, but does not allow a number to be associated with the amount of draw. A good quality Multimeter will have jacks located on the front to allow a 20 amp load to be placed across the leads. The meter is placed between the battery post and removed terminal (as you did the light bulb. Using that, a good amp meter, or a hold against the wire meter (cheap at the auto parts store), Will measure the actual draw (which should be about 3 to 4 amps with the points closed, and near nothing with them open. JimN

Double check the insulators on the threaded contact going through the distributor case. Still can't quite think where 7 amps is getting away--without being a dead short. If a lead/ terminal end in the dist. were going to ground, it would show up as melted insulation or a black/ smoky area. Maybe you are going to have to disconnect the condenser just to make sure that it isn't "leaky".