Alternator Question

Having issues with my TO20 charging the battery. I currently have a 3 wire alternator on it. I've had to jump it every time recently to start it. Once it starts, I can remove the jumper cables and it runs fine. Once I shut it off, it is dead again. Can an alternator provide the juice for the tractor to run off of and not charge the battery at the same time?

Is it more likely that I have a wire crossed or that something is wrong with the alternator?
 
I remember back in the 60's when alternators started to become standard, you could disconnect the battery with the engine running and it would run on the alternator. This was not the case with a generator on the car. A decided advantage for the alternator movement.
 
(quoted from post at 11:01:17 08/23/13) I remember back in the 60's when alternators started to become standard, you could disconnect the battery with the engine running and it would run on the alternator. This was not the case with a generator on the car. A decided advantage for the alternator movement.
believe you have that bass ackwards.
 
The story goes that the generator
"Generates" electricity. Thusly you can safely remove the cables from the battery.
The "Alternator" produces alternating voltage with the diode trio to donvert it to DC voltage. When you disconnect the battery, the alternator goes into "Full field" mode. It tends to generate maximum voltage and amperage due to no reference voltage.
This means you can get 27 volts and about 200 amps out of an alternator gone wild.
Yes, there us a very good chance you can disconnect the alt and it will continue to run.
I did it on my "82 car quite a few years ago.
It only cost me $207 for a new ignition module. I watched jiffy jube do it to a custom,ers car a few weeks ago. It survived the ordeal. At what cost? How many little computer boards got the zap of the shortened life?
You can do as you desire. Me? I got my $207 education before I found out what happened.
 
(quoted from post at 09:59:43 08/23/13) The story goes that the generator
"Generates" electricity. Thusly you can safely remove the cables from the battery.
The "Alternator" produces alternating voltage with the diode trio to donvert it to DC voltage. When you disconnect the battery, the alternator goes into "Full field" mode. It tends to generate maximum voltage and amperage due to no reference voltage.
This means you can get 27 volts and about 200 amps out of an alternator gone wild.
Yes, there us a very good chance you can disconnect the alt and it will continue to run.
I did it on my "82 car quite a few years ago.
It only cost me $207 for a new ignition module. I watched jiffy jube do it to a custom,ers car a few weeks ago. It survived the ordeal. At what cost? How many little computer boards got the zap of the shortened life?
You can do as you desire. Me? I got my $207 education before I found out what happened.

I'm not trying to do anything except figure out if my alternator is going bad or if I have my wiring screwed up. I don't understand how my tractor will run and not charge the battery at the same time. That was my question, not if I can unhook something and operate the tractor.

If anyone has a wiring diagram for a TO-20 with a 3 wire alternator, I would appreciate seeing it.
 
go to fergusontractors dot org, click on resources then wiring diagrams. Use diagram listed as 2 wire alternator (it is 3 wire diagram)

Assuming you have a Delco alternator. With switch off you should have battery voltage at large output stud on rear of alternator and at #2 pin on the plug. Zero volts at #1 pin.

With Switch on, not running, you should still have battery voltage at stud and #2, but should now see some voltage at pin 1. (I've seen it start charging with only 4 volts on pin 1.)

If voltages missing troubleshoot for broken wires or bad connections. If voltages are present your alternator is probably due for exchange.

Also check that your fan belt is not loose.
 
Here is a diagram for a Delco 2 wire on a Ferguson. Most people use a 10Si alternator when they convert them. As far as your problem, is it possible for the tractor to run and not charge the battery? Absolutely...it doesn"t take many amps or volts to fire a points distributor. That"s the only draw on the alternator while it"s running unless you have the lights on.

http://fergusontractors.org/fena/wp-content/uploads/Delco-2-wire-Alternator.pdf
 
(quoted from post at 11:03:02 08/23/13) Here is a diagram for a Delco 2 wire on a Ferguson. Most people use a 10Si alternator when they convert them. As far as your problem, is it possible for the tractor to run and not charge the battery? Absolutely...it doesn"t take many amps or volts to fire a points distributor. That"s the only draw on the alternator while it"s running unless you have the lights on.

http://fergusontractors.org/fena/wp-content/uploads/Delco-2-wire-Alternator.pdf

Thanks to all for the info. I just got back from O'reillys and the old alternator wouldn't run in the tester for 5 seconds before shutting off the machine and issuing a "fail". Bought a new one.

I'll put this one one and see what happens...
 
My tractor also has no "idiot" light nor does it have any kind of diode between the #1 terminal of the alternator and the key switch. Is this why it doesn't turn off when I turn the key off?
 
The general answer is "yes" but I have no idea how
you've got everything wired.

#1 - what do you have for an "ignition" switch?
If when turned "on" it connects your battery-
positive to your coil - it will run regardless of
what the alternator is doing.

Considering that once "off" and you try to restart
- and you've got no spark - it sounds obvious that
there is no 12 volts-positive wired to your coil
from your ignition switch. It DOES sound like
you've got a connection between your alternator
and your ignition. Since you've got it hooked up
"two wire" I assume and not "three wire", the
field-exciter circuit on the alternator is
probably backfeeding to your ignition circuit when
charging and keeping it running. Just a guess
since I have no idea how you've got it wired. The
exciter wire goes to the plug-in connection post
#1.

By the way - there's a subtle difference between
"two wire" and "three wire." Two-wire is when
you loop the small voltage-sensing wire (#2 at the
plug-in connectors) back to the big post on the
alternator. Three-wire is when you run that
voltage sensing wire all the way to the battery.
It serves no purpose on a tractor since the
battery is often close. It IS used on autos
because the voltage at the battery tends to be
slightly different then at the alternator output
post.
 
Yes...as long as you have that top link bracket and the lift arm extensions it will fit fine. I have one I use on my TO-20.
 
What we're calling an alternator here is just a certain type of generator. In the UK they are all just "dynamos."

The old "generators" on tractors made AC just like the modern day "alternators." The difference is - the old "generators" use brush placement to select just a fraction of the electrical pulses made and send it through the brushes as DC current. Much of the power generator is wasted. Thus the reason why they are big for the low output the make.

A modern day "alternator" type of generator uses all the AC it makes and sends it through full-wave rectifiers so it's all converted into DC. Also the brushes do not carry any of the output power.

The old cars that did not run when the battery got unhooked did so because of the way the mechanical regulators were wired up. It had nothing to do with the old brushed generator itself. The old brushed generators were better able to make DC power all on their own due to residual magnetism. The newer tech "alternators" mostly rely on 12 volts of "exciter" current fed to them to create enough field magnetism to charge. That being said - alternators also have a bit of residual magnetism and some can self-start just like the old generators if spun fast enough.
 
(quoted from post at 13:53:48 08/23/13) Yes...as long as you have that top link bracket and the lift arm extensions it will fit fine. I have one I use on my TO-20.

Well, my father mowed with the 14-15 on his TO20 for years without the top link bracket, the extensions or the correct under axle bracket. My father passed away this fall and I inherited all his equipment. I cut the field with it back in June and it was a pain so I started reading and learned about all the missing brackets. So far I've found the correct under axle bracket with the ball socket and the top link bracket. No luck on the extensions yet, but I'm still lookin.
 
(quoted from post at 13:49:37 08/23/13) The general answer is "yes" but I have no idea how
you've got everything wired.

#1 - what do you have for an "ignition" switch?
If when turned "on" it connects your battery-
positive to your coil - it will run regardless of
what the alternator is doing.

Considering that once "off" and you try to restart
- and you've got no spark - it sounds obvious that
there is no 12 volts-positive wired to your coil
from your ignition switch. It DOES sound like
you've got a connection between your alternator
and your ignition. Since you've got it hooked up
"two wire" I assume and not "three wire", the
field-exciter circuit on the alternator is
probably backfeeding to your ignition circuit when
charging and keeping it running. Just a guess
since I have no idea how you've got it wired. The
exciter wire goes to the plug-in connection post
#1.

By the way - there's a subtle difference between
"two wire" and "three wire." Two-wire is when
you loop the small voltage-sensing wire (#2 at the
plug-in connectors) back to the big post on the
alternator. Three-wire is when you run that
voltage sensing wire all the way to the battery.
It serves no purpose on a tractor since the
battery is often close. It IS used on autos
because the voltage at the battery tends to be
slightly different then at the alternator output
post.

The ignition switch I have is a key switch bought from Tractor Supply for my tractor.

I have a three wire alternator with the sensing wire connected back to the battery post on the alternator.

I never said I didn't have spark. When I shut my tractor back off, the battery is completely dead and will not crank the engine over. As soon as I hook up the jumper cables, it fires right up.

I'm going to put a new alternator on tonight and see what happens.
 
Most people just make the 8 3/4" extensions. I got lucky and found an original set for mine. I have hooked mine up once without the top link bracket and extensions and it was way harder to hook up than it would be normally, plus I lifted mine up and it jammed the lift and wouldn't come back down. If you have all the parts you can hook that mower up in about 5-10 mins. The biggest thing I have found is to have the left hand side of the mower sitting on a piece of a 2x4 so it is a little higher than the right hand side and take the right hand check chain loose until you have the mower installed and then hook it back up.
 
I misunderstood. I assumed you were doing all this
with a charged battery. Are you sure your
alternator hook-up isn't draining the battery?
Obviously the alternator is charging or the
machine would not run with a stone-dead battery.
So the question in my mind is - why isn't the
current that is suppling the ignition coil making
its way to the battery to charge it?

Seems either your alternator output is not
connected to the battery - or you've got a bad
battery - or your alternator is draining it after
shut-down.

How are you getting current to the #1 exciter on
the alternator? You cannot wire it directly to
the IGN terminal on the key-switch unless you
stick in some resistance or a diode. You CAN run
it to the ACC terminal which is isolated from the
IGN when the key is off. I'm assume that part is
working OK if the engine shuts off when you turn
the key off.
 
Based off one wire diagram I found, I ran the wire from the bat terminal on the alternator straight to the ammeter and then to the battery out the other side of the gauge. The gauge needle wasn't moving at all and I believe there was no current coming out the other side going to the battery. I bypassed the ammeter and ran that wire straight to the battery and after running for a couple minutes, I shut the tractor off and it started back up without jumper cables. I bought a new ammeter tonight and will install it another day.

I would like to put together a correct diagram for those with TO20s running a 3 wire alternator and 12v coil with an ammeter and charge light. I'm attaching a diagram that I will correct as I'm given advice. Please look at it and tell me what is wrong with it as is. Then please tell me where to put the ammeter and the charge indicator light. Maybe we can get a good one to post.


mvphoto20101.jpg
 
I hope I can say all this without being too long winded.
1. An ammeter is a limited help in monitoring the charging system. It's kinda outdated for this purpose. But I will try to shed some light on its proper use. Basically an ammeter indicates how much current (ampere not necessarily volts) are traveling and what direction they are traveling through a wire or circuit. In other words an ammeter hooked up backwards could fool you into thing a battery is charging (electricity flowing to the battery ) or discharging (current flowing away from the battery).In other words if I hook an ammeter backwards in a system that is working correctly it would show the battery as discharging ,while it was actually charging. if the ammeter is between the generator or alternator, and big lug that all the wires go on it will only show if the alternator is putting out so many amps. If the ammeter is placed between the battery and the terminal that all the accessories are on (lights -ignition -whatever)BUT NOT THE starter. It will indicate whether the battery is getting charged or discharged by the charging source. Remember the ammeter is only equivalent to about a 10 gauge wire.

In your diagram I would use at least 10ga wire from the batt side of the alternator to the power side of the ign switch then another 10ga wire from the switch power side to the ammeter then on to the starter switch. this way the ammeter is indicating the current to the battery (which will include what the alternator puts out) as well as tell if the alt output is enough to carry all the accessories. Remember if the ammeter reads wrong it sould be hooked up backwards - it would still run & charge but indicate a discharge equivalent to what it is charging.



Personally I prefer a volt meter.

 
Please excuse my poor revision of your drawing (if you wanna call it that-its ben a few years since I had to draw something up) this may give you some ideas. Remember to power any accessories from some where on the alt side of the ammeter.use 10 gauge wire for any circuits that carry a heavy load , and that the ammeter is big enough to carry the amperage of the alternator.

I hope this helps. If you like my # is 918-485-3567 Mr Bill
a126239.jpg
 
Boy I screwed this up. I didn't pay close attention to the IGN coil & dist at top (hard for me to see the print.I was mistaken the IGN switch at the bottom for "ign coil" My apology. So I drew it with 2 ign switches.
 
Not to muddy the waters any further.........but. I've been researching this very topic because I'm putting a Delco 3 wire alternator on my TO-35. I found a very good write up on the topic here.
http://bob_skelly.home.comcast.net/~bob_skelly/alternator_conversion/wiring_alternator1.html
If you simply connect the #2 wire from your diagram to the B+ terminal right at the alternator you do not get the full benefit of having a 3 wire alt and that is that it senses the voltage at whatever point you connect the other end of the wire from term. #2 (sensing). The link I provided explains it better than I could. Just thinking that if you really want to do things right and have the maximum benefit from an alternator conversion, you might as well go all the way, it's not much more difficult. :D
 
(quoted from post at 17:48:31 08/27/13) Not to muddy the waters any further.........but. I've been researching this very topic because I'm putting a Delco 3 wire alternator on my TO-35. I found a very good write up on the topic here.
http://bob_skelly.home.comcast.net/~bob_skelly/alternator_conversion/wiring_alternator1.html
If you simply connect the #2 wire from your diagram to the B+ terminal right at the alternator you do not get the full benefit of having a 3 wire alt and that is that it senses the voltage at whatever point you connect the other end of the wire from term. #2 (sensing). The link I provided explains it better than I could. Just thinking that if you really want to do things right and have the maximum benefit from an alternator conversion, you might as well go all the way, it's not much more difficult. :D

I think I read the same article. My tractor has absolutely zero accessories that run of the electrical system. No lights, no nothing. So, for me, there really is no reason to run the sensing wire to another location to get 12v at that spot. Probably wouldn't hurt, but at the moment I just would like for my ammeter to work.... :)
 

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