Hot Coil and voltage

clint s

Member
The coil on the 200 continues be hot to the touch. Not sizzle your finger hot, but hot enough that it is a touch uncomfortable to grab. How hot do they get, and what would cause it if it is not normal.

Here are voltage readings when running at about 1/2 throttle.
At battery 14.9
At coil coming in from battery 14.9 volts
From coil to distributor 6.9 volts
When test alternator without battery hooked up WAY UP to 17 volts.
Wiring is a bit cobbled, has been that way for a long while, but "seems'' right at quick glance.
Is the alt supposed to jump that high with no battery connected and how does the other voltage look.
 
You should NEVER unhook a battery with the engine running it is a safety hazard. It can in fact cause voltage and amps high enough to kill a person and also very good chance of letting the smoke out of the alternator.. An alternator with out a battery hooked up goes to max charge and that in turn can blow the diodes and then you can have 90 plus volts which if you get across the cables some how can kill.
That all said yes a coil will get very warm to the touch and is in fact normal
 
"At battery 14.9"

That"s a bit on the high side, Id expect more like 14+ from an alternator at high RPM, but that"s almost 15 volts!!! Maybe a bad Voltage Regulator???


"At coil coming in from battery 14.9 volts"

It should be near battery voltage if the ignition switch is in good shape. This is for the coils small input terminal that is wired down from the ignition switch when its turned on, THAT WHAT YOU MEANT?????????


"From coil to distributor 6.9 volts"

If the points are closed (as they usually are when shes just sitting there not running) or if its an elec switch that is closed/conducting, the small coil output terminal that wires to distributor SHOULD READ NEAR ZERO VOLTS (to frame ground) as its effectively at ground potential via closed points.

If its a 6 volt coil and you have an external series voltage dropping (12 to 6) ballast resistor THAT ARE USUALLY WIRED BETWEEN IGN SWITCH AND COILS INPUT but you have it between coils output and distributor (wrong place), it would normally drop around 6 volts, but it should still be zero at the distributor if points are closed.

DO YOU HAVE A 6 OR 12 VOLT COIL??????? If you use a 6 volt on a 12 volt system and DO NOT use an external series ballast resistor the coil will get extremely hot (cant keep hand on it) and the points will burn up quickly.

If theres no load on an alternator its voltage can rise too high DO NOT DO THAT!!!!!!!!!!!

We need more info

John T
 
(quoted from post at 13:53:16 09/08/14) You should NEVER unhook a battery with the engine running it is a safety hazard. It can in fact cause voltage and amps high enough to kill a person and also very good chance of letting the smoke out of the alternator.. An alternator with out a battery hooked up goes to max charge and that in turn can blow the diodes and then you can have 90 plus volts which if you get across the cables some how can kill.
That all said yes a coil will get very warm to the touch and is in fact normal
Thanks old I will not do that again.

Going up and checking the wiring it seems to be wired wrong or at least different. It is wired with tab #1 jumped to the bat stud and tab #2 going to something in the tangle of wires inside the box. When I switch the wires around it will not charge. To me the voltages seem ok or a bit high, but I wanted to ask. If it is normal for the coil to be hot to touch (again not sizzle your finger, but uncomfortable to grab) I will leave as is for now.
Just had neck surgery so unable to be much of anything, but plan to rewire it at some point and put a volt meter in I think. The amp meter is broken. It has been wired like this for more than a few years.
 
[color=red:25109c1b5a]
(quoted from post at 14:19:22 09/08/14) "At battery 14.9"

Yes 14.9 volts between positive and negative battery posts[/color:25109c1b5a]



That"s a bit on the high side, Id expect more like 14+ from an alternator at high RPM, but that"s almost 15 volts!!! Maybe a bad Voltage Regulator???


"At coil coming in from battery 14.9 volts"

It should be near battery voltage if the ignition switch is in good shape. This is for the coils small input terminal that is wired down from the ignition switch when its turned on, THAT WHAT YOU MEANT?????????



[color=red:25109c1b5a]Yes when the tractor is running I have 14.9 volts at the small (negative??) post that runs from ignition switch to coil not running battery voltage is present
[/color:25109c1b5a]

"From coil to distributor 6.9 volts"

If the points are closed (as they usually are when shes just sitting there not running) or if its an elec switch that is closed/conducting, the small coil output terminal that wires to distributor SHOULD READ NEAR ZERO VOLTS (to frame ground) as its effectively at ground potential via closed points.


[color=red:25109c1b5a]When the tractor is running there is 6.9 volts at the post on the distributor, when not running and points closed there is 0 plus or minus volts. [/color:25109c1b5a]


If its a 6 volt coil and you have an external series voltage dropping (12 to 6) ballast resistor THAT ARE USUALLY WIRED BETWEEN IGN SWITCH AND COILS INPUT but you have it between coils output and distributor (wrong place), it would normally drop around 6 volts, but it should still be zero at the distributor if points are closed.

DO YOU HAVE A 6 OR 12 VOLT COIL??????? If you use a 6 volt on a 12 volt system and DO NOT use an external series ballast resistor the coil will get extremely hot (cant keep hand on it) and the points will burn up quickly.

[color=red:25109c1b5a]12 volt coil no external resistor needed[/color:25109c1b5a]

If theres no load on an alternator its voltage can rise too high DO NOT DO THAT!!!!!!!!!!!

[color=red:25109c1b5a] Thanks won't do that again😓😓😓[/color:25109c1b5a]

We need more info

John T
color=red:25109c1b5a][/color:25109c1b5a]


Trying to figure out if I do have increased voltage and if I do is it making my coil hotter than it should be.
 
If its a Delco 10SI family of internally regulated 3 wire alternators, the small No 1R terminal is for excitation and usually gets voltage via the coils input or ign switch output when turned on and it has a diode or resistor in series to prevent run on with switch off. The No 2F terminal is voltage sense and its the one that often jump wires to the big main output stud.................

John T
 
(quoted from post at 14:34:22 09/08/14) If its a Delco 10SI family of internally regulated 3 wire alternators, the small No 1R terminal is for excitation and usually gets voltage via the coils input or ign switch output when turned on and it has a diode or resistor in series to prevent run on with switch off. The No 2F terminal is voltage sense and its the one that often jump wires to the big main output stud.................

John T

It is a 10 SI I think it is wire wrong ,but functional?????. I have a battery cut out because I do not have a diode or lamp and it will run down if not disconnected
 
Sort of understand that surgery since I have had surgery on my lower back and have hurt ever since but at least not as bad as it had been.
 
Buy the 12 volt coil P/N 1C14 from Napa that doesn't require a ballast resistor. Your charging voltage is a little too high. Have you had to add water to your battery often? Hal
 
The voltage at the distributor with the ignition on and engine not running should be either battery voltage or no voltage. This is true whether or not you has a ballast resistor in series with the ignition feed on the coil. With the engine running the voltage will be constantly changing between those two values. The voltage you are seeing indicates that the points are closed about half the time and open about an equal amount of time. Your meter is not able to react to the changes in voltage fast enough so what you are seeing is an average of the two values.

To determine whether or not you should have a ballast resistor you need to measure the resistance of the coil. If the resistance is about 1.5 - 2 ohms use a ballast resistor of the about same value. If the resistance is 3.5 - 4 ohms do not use a ballast resistor.
 
(quoted from post at 16:35:02 09/08/14) Buy the 12 volt coil P/N 1C14 from Napa that doesn't require a ballast resistor. Your charging voltage is a little too high. Have you had to add water to your battery often? Hal

Hal that is the coil I have
Battery is ''sealed'' type so no service.
I thought a bit high on the voltage. I will have to look and see if I have another alternator around somewhere.
I was thinking it should be around 13.5 to 14 volts
Owen I should not need one (a resistor) due to having that coil, but should I check anyway.
 
(quoted from post at 15:15:36 09/08/14) Sort of understand that surgery since I have had surgery on my lower back and have hurt ever since but at least not as bad as it had been.

Old thanks for the thoughts, I still hurt some, but it is getting better every day. MD says I should be good to go when all healed up, but that could take up to a year.
 
They get warm, would not worry, but on the other hand, you should make or buy a good harness for the tractor with an alternator. You are asking for a good fire if you do not. The only thing protecting the wires on my farmall when I got is was the corrosion on the outside.
 
Clint,

While we are on the topic of doing work after a surgery. It takes a while to get all the drugs out of your system. Try to avoid doing dangerous or things that take a lot of judgement.

I got in a snot after surgery and did a bunch of things that I am re-doing later.
 
My back problem has me not being able to do a full time job any more. I have a limit if 35lbs but who can live and keep in that limit?? Oh well I do as much as I can when I can and if I start to hurt to much I take a break. My doctor told me flat out your retired and boy when that happen you have no choice but to retire
 
It's common for a Delco 10SI with the automotive regulator to run 14.8-14.9 V , a little hotter than I think necessary for a tractor. If you specify it when you buy an alternator or change your own regulator, you can get 14.2 V regulators designed for AG, construction or marine use for the same price.
Most of the Delco alternators I rebuild are for AG use, so I buy 14.2V regulators in boxes of 10.
 
(quoted from post at 21:01:30 09/08/14) It's common for a Delco 10SI with the automotive regulator to run 14.8-14.9 V , a little hotter than I think necessary for a tractor. If you specify it when you buy an alternator or change your own regulator, you can get 14.2 V regulators designed for AG, construction or marine use for the same price.
Most of the Delco alternators I rebuild are for AG use, so I buy 14.2V regulators in boxes of 10.

Thanks Jon,
By the sounds of it, it is ok as it is running 14.8 to 14.9 volts. Thinking of getting a rebuild kit and will get a 14.2 marine/Ag one.

My surgery was 2 months ago and am still working on 5# restrictions. Have a MD in 2 weeks to hopefully get it lifted and start getting ready to get back to work. My surgery was relatively routine taking about an hour and went well so the surgeon expects a full recovery. In had a fusion so I will just lose a bit of range of motion
 
Yeah, 14.8 is about typical in a vehicle, so the alternator is working as it should.

If the ammeter drops back down close to 0 when the tractor is running, but no lights or anything else, it is working fine. When it stays at a high charge rate all the time, is when you start looking for problems.

The coil may or may not be too hot. I don't know what your idea of hot is.

One thing you need to be careful of is that there are *TWO* different types of "12V" coils. There is a "ballast resistor required" and a "no ballast resistor required." It is easy to imply the "no" if you're reading the package quickly and end up with what is really a 6V coil.
 
Your alternator probably needs a new regulator if it has the internal regulator. A repair shop that rebuilds starters, generators and alternators
can check out the problem on a test stand. 14.0 to 14.5 volts would be ok. Hal
 
(quoted from post at 04:48:14 09/09/14) Yeah, 14.8 is about typical in a vehicle, so the alternator is working as it should.

If the ammeter drops back down close to 0 when the tractor is running, but no lights or anything else, it is working fine. When it stays at a high charge rate all the time, is when you start looking for problems.

The coil may or may not be too hot. I don't know what your idea of hot is.

One thing you need to be careful of is that there are *TWO* different types of "12V" coils. There is a "ballast resistor required" and a "no ballast resistor required." It is easy to imply the "no" if you're reading the package quickly and end up with what is really a 6V coil.

There was an 1C14 from Napa on it and I replaced it with the same. No difference in temperature.
It was used for 2 hours tending hay before I tested it and the battery was not hot and voltage stayed steady at 14.8 to 14.9
The coil is hot enough to want to let go of if you grab it, but not so hot that it burns you. (you could hang onto it with no ill effects).
EDIT
So with some research on regulators I confirmed what mkirsch said, that in fact most regulators have a 14.8 set point. When I get to it I may change it out for a lower voltage one to see if it helps with the heat a bit. I am going to take it that my volt readings are normal and the coil is hot, but not overheating.

Tractor is running and starting much better, but stalled out once after tedding coming to low idle when he was done. There was some condensation in the cap, I think from sitting for a month outside so I will chalk it up to that.

I think new cap and rotor, gas tank cleaning, and rewiring should be on the not so short list.
 
I read that when adjusting a water heater thermostat,that 120 degree water is too hot to comfortably keep your hands in it. If your coil is running in the 120-150 degree range, it would feel very hot, but would be in a normal working range.
 
Jon that's what I based my temp on. It's hotter than my hot water, but cooler than when I touch my 180 degree boiler pipes by mistake
 
this happened to me after i did my 12v conversion you will have to take the pulley off of the alternator, go to a shop and get one about o say twice the diameter and put on there that will dial the amperage and voltage back to a usable amount, it really does not take much juice to run one of those tractors, then get a resistor bar from an old Chrysler from the 80's it will be a whit ceramic bar about 3 inches long put that bar next to your coil run your hot wire to one side of the bar and on the other side of the bar run it to coil. if you run the old pulley on the originator you will burn up your gauge i had this happen to me a few time, till my mechanic told me the new alternators are much more aggressive than the old generators so you need to slow them down or find a way to boil off the excess juice
 
(quoted from post at 20:02:53 09/09/14) this happened to me after i did my 12v conversion you will have to take the pulley off of the alternator, go to a shop and get one about o say twice the diameter and put on there that will dial the amperage and voltage back to a usable amount, it really does not take much juice to run one of those tractors, then get a resistor bar from an old Chrysler from the 80's it will be a whit ceramic bar about 3 inches long put that bar next to your coil run your hot wire to one side of the bar and on the other side of the bar run it to coil. if you run the old pulley on the originator you will burn up your gauge i had this happen to me a few time, till my mechanic told me the new alternators are much more aggressive than the old generators so you need to slow them down or find a way to boil off the excess juice

They pulley may work, don't know if there is a ballast resister that only drops a volt or 2. I have a 12 volt coil. For about $10 or so I will get a new voltage regulator to drop the voltage. By the time I got a new pulley paid to put it on I would be out more than that. I am beginning to think that my coil heat is normal.
 

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