Positive Ground

[Darby Creek]

Don't all you old timers laugh at me please.I'm changing my 9n back to positive ground like everyone says it should be,but suppose i had to put a charger on my battery,would i hook my charger up the same way i always have in the past?I realy feel stupid but i want to be sure.

 

[DavidO]

Hook the charger up according to the battery terminals, i.e. pos to pos and neg to neg, regardless of how you have the battery wired to the tractor.

 

[JMOR]

(quoted from post at 12:40:50 08/18/09) Don't all you old timers laugh at me please.I'm changing my 9n back to positive ground like everyone says it should be,but suppose i had to put a charger on my battery,would i hook my charger up the same way i always have in the past?I realy feel stupid but i want to be sure.

avid gave you your answer on your question, BUT, when you reverse the battery connections, don't start it before you re-polarize the generator unless you want to buy a new cut out.

 

[Darby Creek]

OK Thanks guys,i hated to ask that question but it's something i'll need to know someday.

 

[jimNCal]

Why is that stupid? The only 'stupid questions' are the ones UNasked before making (expensive) mistakes. Ignorance is ALWAYS expensive. Listening is free. Keep on asking and learning....it'll save you a ton of $ along the way.
jb
ps....I honestly believe you'll never, in your life, find a place or group of people, more tolerant than the regulars that contribute to this forum. I don't/can't contribute much, but I read it everyday and you'd be amazed at how many newbies don't realise the archives even exist. So...the regulars patiently answer the same questions year in and year out. 'N'joy

 

[bmack95hd]

D.C., Thanks for asking that question. After asking my + vs - question yesterday the same thought crossed my mind that maybe I was hooking the charger up wrong. I will be changing my '51 N back to positive ground when I am done with my post hole digging project.

 

[Roland Jackson]

I agree with Jim....I have been in the tractor business for many years but this is the place where I learn from others. I don't have the time to post that often anymore, but I always read and keep up with the board.

Best Wishes,
Roland Jackson

 

[rzacc]

OK, If the first question is dumb ( which it is not) Mine is dumber.. What is it he cut out? Where is it located?
I bought an 8n that someone stuck in 12 volt battery, neg. gound. Now iM going back to the 6 volt. I think I'll need to polarze the generator (Shorting the two posts, right???).
Any suggestions???
Thanks much in advance.
Ron Z

 

[JMOR]

(quoted from post at 16:10:18 01/18/10) OK, If the first question is dumb ( which it is not) Mine is dumber.. What is it he cut out? Where is it located?
I bought an 8n that someone stuck in 12 volt battery, neg. gound. Now iM going back to the 6 volt. I think I'll need to polarze the generator (Shorting the two posts, right???).
Any suggestions???
Thanks much in advance.
Ron Z

f 8N, it wouldn't have a cut out & single terminal generator, but it would have a Voltage Regulator & a 3-terminal generator. Polarize before starting by a momentary jumper from ARM (sometimes labeled GEN) terminal of Voltage Reg to the BATT terminal of same.
Alternatively, (easier to get hands to) a jumper from un-grounded battery post to ARM terminal on generator rear end-plate.

 

[Jerry Kirkpatrick]

JMOR,

I think I've seen the answer here before, but what happens if he doesn't polarize the generator?

 

[JMOR]

(quoted from post at 17:59:11 01/18/10)
JMOR,

I think I've seen the answer here before, but what happens if he doesn't polarize the generator?

Well, he has a 50/50 chance that the generator may output a voltage of the same polarity as the battery & likewise an equal chance for the opposing polarity. If the same, all is well. If opposite, it goes like this: engine speed increases until generator output voltage reaches a value sufficient to cause a magnetic force in the shunt cut out coil which closes the contacts which connect the generator to the battery. Since at this instant we have (let us say) a generator output of 7.4 volts which is Positive relative to chassis on one of those 2 contact points, whereas we have a battery (POSITIVE GND TO CHASSIS) which presents 6 volts which is Negative relative to chassis on the other of those contact points. That is a difference of 13.4 volts. We have a generator trying to make the battery Positive and a battery which is trying to make the generator Negative. Neither will like this and the opposing forces will make a big spark/arc/flash as the contacts touch one another. The series coil in the cut out will sense this current & try to open those contacts, but once open the shunt coil will immediately act to close them again. This oscillation may continue for awhile, all the time damaging the contacts, OR they may become so hot/molten as to weld the 2 contacts together, OR if you get lucky, the battery will win the contest quickly and re-polarize the generator (to match battery) and everyone will live happily ever after. Are you willing to bet the cost of a new VR or cut out on the happy ending? Illustration follows:

 

[Jerry Kirkpatrick]

Thanks...great answer. I appreciate the detailed explanation and know others will, also. Just my learning style...knowing the "why" of something helps me remember to do it. My first flight instructor taught me how to do power-on stalls and power-off stalls and to recover with the least possible loss of altitude, but NEVER explained why were doing them. Only after I discovered WHY on my own (by reading, not flying) did I develop the respect for that aspect of flying that it merited.