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Ford 9N, 2N & 8N Discussion Forum
Show Parts for Model:

Ford 8N Battery Polarity is reversed

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Marc H

08-15-2014 12:28:58
216.252.5.248



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Hi!

I got a new Ford 49 8N this summer. (New to me.) The battery is wired with (+) ground, as it should be. When I measured the battery with a meter, it was reverse polarized. (Yes... I checked the meter connections.) I have read the blogs where you have to polarize the generator and regulator. I know that the previous owner rewired the tractor, and that it works, and still works. My questions are:

1) Is it wired backwards?

2) Could it be wired correctly and still have the battery reverse charged?

3) If it is wired correctly, is it possible that the battery is reverse charged because the generator and/or regulator was polarized incorrectly?

4) Can the polarization change spontaneously?

Thanks!

-Marc

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R Geiger

08-15-2014 21:02:41
50.38.94.127



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 Re: Ford 8N Battery Polarity is reversed in reply to ScubaInstr, 08-15-2014 12:28:58  
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I wish him luck with the battery.



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Bob

08-15-2014 22:06:19
64.255.159.192



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 Re: Ford 8N Battery Polarity is reversed in reply to R Geiger, 08-15-2014 21:02:41  
"I wish him luck with the battery. "

As do I.

In my experience, I think there's at least a fair chance it will be OK.



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Marc H

08-16-2014 05:40:33
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 Re: Ford 8N Battery Polarity is reversed in reply to Bob, 08-15-2014 22:06:19  
Jumping in on my own question...

Since I am new to this, how do I tell which terminal is the armature on the generator? Also, does it matter if the key is in the of or run position? And, will there be a big spark when I do this?

Thanks for all of your help!



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R Geiger

08-16-2014 10:51:37
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 Re: Ford 8N Battery Polarity is reversed in reply to Marc H, 08-16-2014 05:40:33  

Marc H said: (quoted from post at 21:40:33 08/16/14) Jumping in on my own question...

Since I am new to this, how do I tell which terminal is the armature on the generator? Also, does it matter if the key is in the of or run position? And, will there be a big spark when I do this?

Thanks for all of your help!
the big one, switch off, small spark!

I would suggest you get a FO-4 service manual if you do not have one.


This post was edited by R Geiger at 11:00:33 08/16/14.

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Marc H

08-16-2014 16:26:41
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 Re: Ford 8N Battery Polarity is reversed in reply to R Geiger, 08-16-2014 10:51:37  
Thanks!

The service manual is in the mail!



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R Geiger

08-15-2014 20:42:40
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 Re: Ford 8N Battery Polarity is reversed in reply to Ken N Tx, 08-15-2014 12:28:58  
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If the battery has been damaged as you say is possible then why the heck not have it checked by a battery shop. A volt meter tells you nothing, as you should know!



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Bob

08-15-2014 20:53:29
75.238.135.37



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 Re: Ford 8N Battery Polarity is reversed in reply to R Geiger, 08-15-2014 20:42:40  
Recharging it with the correct polarity, and seeing if the tractor cranks well costs next to nothing.

If the recharged battery does NOT crank the tractor well, a new one is needed.

Don't know WHERE the need to disconnect it/remove it and drive it to a battery store have it "checked " before even giving it a try enters into that equation!



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R Geiger

08-15-2014 20:39:01
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 Re: Ford 8N Battery Polarity is reversed in reply to Richard from SE AZ, 08-15-2014 12:28:58  
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I have only seen in on nicad batteries in aircraft. I still think it is rare as hen teeth in lead acid batteries regardless of what you say.



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mwbailey

08-15-2014 19:50:30
67.197.60.58



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 Re: Ford 8N Battery Polarity is reversed in reply to Caryc, 08-15-2014 12:28:58  
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OK, Bob, I'll broaden my horizon and comment that a lead acid battery is interesting in that both poles move toward becoming lead sulfate as the battery discharges. So, a fully discharged battery that is "charged backwards" takes the new order of things. Experience is often much better than "theory"!?!? Still, I wonder if a battery that has been charged backwards would really perform as well as one that has been charged "properly". . . .

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Bob

08-15-2014 20:31:16
75.238.135.37



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 Re: Ford 8N Battery Polarity is reversed in reply to mwbailey, 08-15-2014 19:50:30  
"Still, I wonder if a battery that has been charged backwards would really perform as well as one that has been charged "properly""

You are correct, it probably won't be as good as it was before.

Can't help that.

Nor, can we eliminate/rule out well-meaning folks charging batteries backwards.

Stuff happens.

When you have been dealing with the public/repairing stuff as long as I have (40+ years) and think you have "seen it all", you HAVEN'T.

So it never hurts to keep an open mind, and do some research before ruling out something you haven't seen/ heard of before!

(And there's no reason to be be irritated at the messenger that enlightens you!)

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Royse

08-15-2014 17:18:54
69.36.49.186



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 Re: Ford 8N Battery Polarity is reversed in reply to Marc H, 08-15-2014 12:28:58  
Is there any reason to change it right now?

If not, I'd consider leaving it until you had to replace the battery.

That old saying: "if it ain't broke, fix it until it is!"



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R Geiger

08-15-2014 15:58:48
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 Re: Ford 8N Battery Polarity is reversed in reply to strifecr, 08-15-2014 12:28:58  
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The starter does not care what the polarity is. It would work either way.
I would take the battery to a battery shop and have it checked out.



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Bob

08-15-2014 18:49:01
75.238.54.247



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 Re: Ford 8N Battery Polarity is reversed in reply to R Geiger, 08-15-2014 15:58:48  
"I would take the battery to a battery shop and have it checked out."

And that would accomplish WHAT??? ASSUMING the OP is reasonably competent with a voltmeter, he has ALREADY diagnosed the problem!



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Bob

08-15-2014 14:09:32
75.235.15.31



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 Re: Ford 8N Battery Polarity is reversed in reply to Marc H, 08-15-2014 12:28:58  
At some point, the battery was stone-cold dead, and a well-meaning person didn"t realize that the post connected to the chassis was the (+}) post, and he connected the charger backwards.

I have seen the exact thing a number of times over the years.

The fix is to COMPLETELY discharge the battery. A spare headlight and a coupe of jumper wires works great for that.

Then, connect a battery charger correctly and recharge the battery.

Before starting the engine, polarize the generator to the new (correct) battery polarity.

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Marc H

08-15-2014 15:11:08
216.252.5.248



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 Re: Ford 8N Battery Polarity is reversed in reply to Bob, 08-15-2014 14:09:32  
I can discharge the battery. How do you polarize the generator? Is there a procedure online for that?

Also, how is it that the tractor started and worked all of this time? Would the starter not spin backwards?



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soundguy

08-15-2014 16:48:04
207.30.46.70



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 Re: Ford 8N Battery Polarity is reversed in reply to Marc H, 08-15-2014 15:11:08  
jumper the non grounded bat post to the armature on the generator while not running... only takes a second or two..



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Marc H

08-15-2014 16:51:42
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 Re: Ford 8N Battery Polarity is reversed in reply to soundguy, 08-15-2014 16:48:04  
Thanks. Do I need to disconnect the generator when I do this?



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soundguy

08-15-2014 17:15:53
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 Re: Ford 8N Battery Polarity is reversed in reply to Marc H, 08-15-2014 16:51:42  
uh.. you could.. but it would defeAT the point!



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Bruce (VA)

08-15-2014 17:03:02
24.125.183.11



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 Re: Ford 8N Battery Polarity is reversed in reply to Marc H, 08-15-2014 16:51:42  
" Do I need to disconnect the generator when I do this? "

If you disconnect the generator.......it won't polarize.

Check out tip # 23 at the link.



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Jon Hagen

08-15-2014 15:58:37
69.26.17.61



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 Re: Ford 8N Battery Polarity is reversed in reply to Marc H, 08-15-2014 15:11:08  
The starter does not care about + or - ground, it always turns the correct way because both armature and wire wound fields are reversed when bat polarity is changed.

Only a starter with permanent magnet fields (like a small engine starter(lawn tractor) will run backwards when the battery polarity is reversed.

A dead battery can be recharged backwards as Bob says.

If the tractor is starting and charging this way, does the ammeter read correctly, or does it show discharge when actually charging ? If the ammeter works correctly with neg ground, the conversion to neg ground may have been intentional.

Also,your battery may not survive another total discharge and recharge, as that deep cycling causes the battery plates to warp, twist, shrink, swell, which can shed plate material, puncture a separator, bridge two plates and short a cell. Not much lost though, as you dare not leave the battery reverse charged for safety reasons.

Someone else will have to post the polarizing procedure for your tractor.

In my opinion, a pos ground system in a 99.9% neg ground world is a dangerous odd ball that can get someone injured by wrongly connecting booster cables or charger and causing a battery explosion.
If it was mine, it would remain Neg ground.

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R Geiger

08-15-2014 12:54:32
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 Re: Ford 8N Battery Polarity is reversed in reply to NNP, 08-15-2014 12:28:58  
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More likely you are looking at some wrong!



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mwbailey

08-15-2014 14:02:55
67.197.60.58



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 Re: Ford 8N Battery Polarity is reversed in reply to R Geiger, 08-15-2014 12:54:32  
Interesting issue, but I'm pretty sure batteries only "discharge" electrons from one pole and are recharged in the opposite direction -- it's the chemistry of the thing! So, doubtful that a battery would reverse it's polarity. . . .



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Bob

08-15-2014 18:51:15
75.238.54.247



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 Re: Ford 8N Battery Polarity is reversed in reply to mwbailey, 08-15-2014 14:02:55  
Bailey and Geiger... you guys need to broaden your horizons a bit/think "out of the box" once in a while!

What the OP has observed is POSSIBLE and has happened before!



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