46 2n not charging

[rick165]

hi i picked up a 1946 2n last summer and it is not
charging.it has been changed to a 12volt alternator
that i had checked out and it is working.it is a 3
wire alternator charging system.my volt meter wont
work while the tractor is running someone told me i
needed a meter with a needle type tester.any ideas.
RICK

 

[Bruce (VA)]

So if you can't get a voltage reading, what makes you think it's not charging? You could have a bad battery.

Yes, you need a cheap analog meter (tip #47) or an expensive digital meter.
75 Tips

 

[Tom Beddard ENC]

Try JMOR's wiring diagram if you kept 6V coil.
Untitled URL Link

 

[Dell (WA)]

Rick........suprizingly enuff, modern digital voltmeters barf 'cuz of sparkies. Ittza technical thing. So gittcha a cheap old fashioned analog meter with a needle display. It is plenty accurate for tractor work and is semi-immune to sparkies. ........Dell, retired electronics calibration lab engineer

 

[rick165]

well first the amp gauge doesnt show charge and when i lift off the positive battery cable it dies.
RICK

 

[Bruce (VA)]

" when i lift off the positive battery cable it dies."

That's an excellent way to burn up the alternator. If it wasn't bad to start with, it probably is now.

The battery acts as a 'load' on the alternator. No load & the alternator burns up.

First, get a set of manuals (tip # 39) before you do some serious damage to the tractor.

Next, charge the battery per tip # 60. Then check it per tip # 49.

Finally, check the alternator output per tip # 47.

Post back w/ results or more questions.
75 Tips

 

[JCinKY]

Aren't you 'sposed to remove the ground from the battery to find out if your alt/gen is charging the ignition circuit?

I hope since you said 12V that you are not still positive ground.

 

[JMOR]

(quoted from post at 09:54:24 03/01/13) Aren't you 'sposed to remove the ground from the battery to find out if your alt/gen is charging the ignition circuit?

I hope since you said 12V that you are not still positive ground.

he disconnect battery technique would sort of work on old generator/electro-mechanical systems of yester-year. I say, sort of, because even then there would be transient voltages (spikes) that are potentially harmful. Problem in doing this with modern alternator systems is that these contain solid state electronics (transistors, diodes, integrated circuits) all of which can be very susceptible to transient (spikes) voltages and be destroyed in tiny fraction of a second (before you can think or blink). Sometimes you will get away with it on some alternator/regulator designs, but other times, it will be back to the store. That is usually $50 or so, but try that stunt on your modern car/truck with dozens of micro-computers/controllers all over the place & you might need thousands of dollars to fix everything.

 

[teddy52food]

Sounds like you fried the diodes.

 

[JMOR]

(quoted from post at 07:58:32 03/01/13) well first the amp gauge doesnt show charge and when i lift off the positive battery cable it dies.
RICK

ould be as simple as the 1 & 2 or Excite & Sense wires are not connected correctly, especially since you say the alternator checked OK.

 

[JCinKY]

(quoted from post at 07:36:13 03/01/13)

(quoted from post at 09:54:24 03/01/13) Aren't you 'sposed to remove the ground from the battery to find out if your alt/gen is charging the ignition circuit?

I hope since you said 12V that you are not still positive ground.

he disconnect battery technique would sort of work on old generator/electro-mechanical systems of yester-year. I say, sort of, because even then there would be transient voltages (spikes) that are potentially harmful. Problem in doing this with modern alternator systems is that these contain solid state electronics (transistors, diodes, integrated circuits) all of which can be very susceptible to transient (spikes) voltages and be destroyed in tiny fraction of a second (before you can think or blink). Sometimes you will get away with it on some alternator/regulator designs, but other times, it will be back to the store. That is usually $50 or so, but try that stunt on your modern car/truck with dozens of micro-computers/controllers all over the place & you might need thousands of dollars to fix everything.

Thats what I figured. I test my 6V generator like that when needed.

I'd never even think about doing it on my truck...

 

[souNdguy]

points may throw off a cheap digital meter.. but try a cheap analog..

and quit unloadingthe alt before you cook it...