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 | Mike Maier
Join Date: Posts: 1 
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2000-08-06 18559
I went to start and Ford 900 that I was thinking about buying and I noticed it had a positive grounded battery. It has a four cylinder gasoline engine. Is the battery hooked up right?
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| richard james allen
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2000-08-06 18562
I have a 52 Ford 8N and the battery is grounded off the positive. From what I was able to find out, this was a common setup for these tractors. This system is 6V and some people have converted their tractors from 6V to 12V. Mabey the reversed polarity is due to the 6V setup? ....
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| Roger L.
Join Date: Jun 1999 Posts: 0
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2000-08-06 18564
Yours is hooked up right. JD also used positive ground at the time. I'm looking at the Ford manual, and the Ford 2N,8N, and 9N was also originally positive ground. As far as I can tell, which terminal to run to ground depends on which technical philosophy has the upper hand at the time. Somehow it seems refreshing to me when the eggheads can't even agree on such a simple thing!! At the time when most industrial and ag machinery was positive ground, the American automobile industry was negative ground. Go figure.....
If you want to do so for some reason, you can reverse the battery polarity on most if not all old brush type generator and voltage regulator system. Both 6 and 12 volt. I've done it and so have lots of others. It does require figuring out what and why to re-polarize. ....
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| Bird Senter
Join Date: Jun 1999 Posts: 962 
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2000-08-07 18573
Are you old to enough to remember when Chrysler product cars had a positive ground? I can't remember when they changed to a negative ground, but the early 50s had the positive ground (I'll probably always remember because I installed a new battery backwards in one). ....
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| Bud
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2000-08-07 18588
Bird I'm with you on the Chrysler products. My Dad had a 1937 dodge and the positive battery post was grounded. The bad part of the whole deal was getting to the battery under the front seat. I think Chrysler is trying to relive the old days on some of their new models. They are hiding the battery.
Bud ....
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| Bird Senter
Join Date: Jun 1999 Posts: 962
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2000-08-07 18589
Bud, I haven't look at any of their new ones lately; didn't know they'd gone back to hiding the battery, but the first car I can remember of my parents' was a 1936 Plymouth coupe. But the one in which I ruined a battery by hooking it up backwards was a 1953. ....
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| Roger L.
Join Date: Jun 1999 Posts: 0
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2000-08-07 18606
Right! I had forgotten about the the "battery under the seat" trick. I had a jeep that was built that way....and my JD still has the battery under the seat today. Frankly, I like it there a lot better than having it in front of the radiator like is so common on compacts. The "weird battery" prize in my garage was won by a 1958 MGA that not only had the batteries under the seat...they were under the rear seat! That's right, it had a 12 volt system composed of two six volt batteries in series. Being British it was positive ground, too! Second prize would have to go to a venerable 48 Hudson belonging to a friend...it had an 8 volt battery which was not uncommon at the time....but I forget which pole was grounded. ....
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| T-ROCK
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2000-08-07 18610
Bud, when I was at a Chrysler new car announcement meeting a couple of years ago, they said they were actually including the battery in the equation for impact or energy absorption when they engineer the new vehicles. I asked them if they were worried about the amount of corrosion on the terminals, and their response was "better to save a life than a couple of cheap battery terminals". That is true, but for us in the dealership, those batteries are a bear to replace! Just my 3 cents worth ....
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 | Art White
Join Date: Jan 2000 Posts: 6898 Waterville New York 
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2000-08-08 18624
From what I have seen all 6 volt systems are positive ground and all 12 volt systems are negative ground. That relates to IH tractors and the older cars I have had. Don't ever remember running into anything else for the other makes I've had experience with. ....
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| Bird Senter
Join Date: Jun 1999 Posts: 962
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2000-08-08 18625
Hmmm, Art, you could be right; I'm getting older and my memory may not be what it once was, but I don't remember the old GM and Ford 6 volt cars being a positive ground; I THINK they were negative ground. But of course it's been over 40 years since I worked in my Dad's service stations, so I can't swear to it. ....
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| MJB
Join Date: Posts: 1
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2000-08-09 18660
Art
Not all 6 Volt systems are positiove ground. Right now I have a 1947 Willys CJ2A which is 6 volt negative ground. I also have a 1952 Case DC-4 tractor which was 6 volt negative ground before I converted it to 12 volt operation. The other older cars that I am familiar with seem to be about evenly split between positive and negative ground on 6 volt systems. When 12 volt systems first came out I think there were a few instances where they used positive ground as well. Sure makes you pay attention when you hook up a battery charger. MJB ....
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| george pacheco
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2000-08-12 18769
Hi guys, as far as I know all 6 volt Ford and Chy products were pos. grounded.
GM used neg grounds on their 6 volt cars. Ford and Chy switched to 12 volt in 1956 and went neg ground then. Chevy went 12 volts in 1955 (exception 6cyl corvette) and stayed neg ground. Chy went to alternators in 61, chevy in 63 and Ford used some in 63 and went full alt in 64.
It is ok to run a 6 volt starter on 12 volts for short burst's, keep in mind that the amperage draw will be higher and the engine will turn over faster.
When switching from pos to neg ground the amp meter and ignition coil leads need to be be reversed and the generator polarized to match battery polarity. Failing to repolarize will put the battery and generator in SERIES giving you 24 volts instead of 12. One advantage in going from 6 to 12 volts is that ALL of the OEM wiring is now of a heavier gauge (twice) of whats needed. An extreme rarity these days.
regards,
george, keoke ....
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| Roger L.
Join Date: Jun 1999 Posts: 0
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2000-08-12 18790
George, does one need to re-polarize the voltage regulator as well? ....
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| mbjacobs
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2000-08-12 18791
Along the same lines, I read the other day that many of the car manufacturers are considering going to 36 volts due to the heavy use of electrical and electronic gizmos in modern cars. This would allow them to use lighter (cheaper) wire. ....
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| george, keoke
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2000-08-12 18794
Roger, volatge regulators do not get polarized. Polarizing is done because DC generators have one north and one south residual magnet. When switching battery polarity these two magnets have to swap polarity, ie, the north needs to go south and south go north. Or if the unit sits around long enough (rebuild) the residual magnets may change polarity on their own. Polarizing is done by flashing the field coils wraped around these magnets with a quick shot of current (electro-magnet) running in the proper direction. However, if you are going to a 12 system from a 6 volt system then the regulator must be changed to a 12 volt unit. This is because the resistance values on the coil windings (heavy gauge stuff) are way to low for the 12 volts now running through them and thus the current values will accordinlgly be far to high. Bottom line, all of this is not going to work very well and most likely will cause smoke.
Since all solid state accessories are now neg gnd, there is no point in doing a 6 to 12 conversion and staying with the pos gnd system.
DC generators require a current limiting relay that alternators do not need. Consequently, the dc voltage regulator must be matched to the generator in both AMPERAGE and voltage. DC generators will easily produce twice their design output,(though not for long) if this current is not limited by the regulator.
Voltage regulators for alternators need only to be matched in voltage for alternators will limit themselves in regard to max current output. In other words, a 100 amp, 12v alternator can use the same voltage regulator as 50 amp 12v unit.
Since it's only watts that count, a typical 6v gen will usually have twice the amperage of a 12 volt unit while producing the same total watts.
Hope the above rambling makes some sense.
best regards,
george, keoke
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| TomG
Join Date: Feb 2002 Posts: 5406 Upper Ottawa Valley
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2000-08-15 18848
Since I haven't been part of the discussion, I guess this is just idle curiosity. The last regulator I changed was on a '53 Chevy (6V -GRD). I recall there were instructions for polarizing something, (the regulator I thought) and the instructions did mention 'flashing the field.' Now, I'm just curious what it was that I did. ....
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| george, keoke
Join Date: Posts: 1
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2000-08-15 18863
Tom G, what you did was to take the generator lead at the regulator off and tap it a couple of times to the battery terminal on the regulator. This sent a shot of current down to the gen pos brush and on to the B+ side of the field coils at the same time. The negative side of the field coils are a modulated gnd by the regulator depending on charge rate. Both magnets got their residual (permanent) magnetism and polarity at the same time. Generators will not work unless these pole shoes become permanent magnets. Alternators field coils get their magnetism when you turn on the ignition switch and consequently do not need the above routine. By the way, if you have a stone dead battery and a dc generator you can push start the vehicle since the pm magnets will get the gen working for the needed ignition current. This trick will not work on an alternator unless you have enough battery current left to magnetize (electromagnet) the field coils and start the charging process.
One last point, only "A" type dc generators are polarized like the Chev Tom has.
Hope the above makes at least a bit of sense.
regards,
george, keoke
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| Roger L.
Join Date: Jun 1999 Posts: 0
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2000-08-15 18878
Tom, George, you sure have got my mind working. After thinking about it
for awhile, it is beginning to come back to me about the polarization of
voltage regulators on the old generator systems. I believe that I do recall
that at least some of the VRs needed to be polarized. It wasn't as critical
as polarizing the generator, but if you didn't polarize the regulator then
sometimes they would just sit there and chatter. Of course othertimes you
would get lucky and they would work right off. What I am talking about is
different than polarizing the generator so that the residual magnetism in
the field shoes would have the proper north/south polarity for + or -
ground.
Taking it a step farther, IF there is a polarization that is specific
to the voltage regulator, then this implies that the regulator itself
contains some component which is sensitive either to the polarity of some
residual magnetism or to the direction of the current flow being regulated.
I agree with George in that when I view the voltage regulator as a
collection of voltage and current limiting relays then polarity is not an
issue. These relays simply compare spring tension to magnetic pull (which
increases as the RPMs go up). And spring-biased relays can easily be made so
that they don't have any residual magnetism and hence don't care about
polarity. But perhaps like the generator there was a reason why they wanted
some magnetism. Maybe I can find an old book which will shed some light on
this (minor) matter. This discussion reminds me of the old days......when
the electrical devices on tractors were capable of being understood with
some physics and an evening of thinking! :-) ....
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| george, keoke
Join Date: Posts: 1
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2000-08-16 18890
Roger, your memories of the VR chattering are right on the mark. The cutout relay on the VR has two sets of windings. One winding in parallel (shunt) and another one heavy gauge in series. The shunt winding is not polarity SENSEITVE but the series one is. The shunt winding is used to initialy pull the contacts together then as the current flows from gen to bat through the series winding the contacts are held together tighter with the pull of both the series and shunt magnetic fields pulling together. However when the gen voltage falls below the bat voltage (idle) then the current flow through the series winding is REVERSED and now the magnetic fld from the series winding is PUSHING up on the relay armature overcoming the shunt windings down pull and forcing the relay open.
This opens the circuit between bat and gen. The chattering comes ONLY from a cutout relay on a gen that has not been polarize correctly. This due to the fact the series winding is getting current flowing through it in the wrong direction (backwards) when coming from the gen and in the right direction when coming from the battery. This causes the relay to latch and unlatch at a rapid rate causing the chattering that you hear. Bottom line, regulators do not need to be polarize but the will fink (chattering) if you do not polarize the gen to get the right polarity from the output terminal.
On alternators the cutout relay is replaced by diodes which serve as a one way check valve (alt to bat) between the charging unit and the bat.
Roger, look up the left hand rule on the relationship of current flow to magentic fields through a conducter.
Hope this helps guys.
regards,
george, keoke ....
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