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Crawfordsville, Arkansas | Trying to get an antique Case backhoe going. No battery and no decals saying pos or neg ground. Any sure fire way to tell before I throw a hot battery on there and make sparks?
This is an old Case hoe. No cab or rops so it's 60's-70's vintage. It is a diesel though. Hasn't been started in 8-10 years but it's loose.
Edited by Detroit 2/22/2016 15:38
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Remsen, Iowa | This is worth what it cost.............. if it has a generator, it is neg ground. If it has an alternator it is positive ground,
Edit....................I was wrong again.
Edited by rambo 2/22/2016 16:15
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| rambo - 2/22/2016 15:40
This is worth what it cost.............. if it has a generator, it is neg ground. If it has an alternator it is positive ground,
If it was a John Deere it would be the other way around. |
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s.w. IA | WD allis had a generator and positive ground originally. |
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SW “Ohia” | rambo,
Very wrong.
Farmall letter series is positive ground with generator. My Cub and Super C are set that way from factory.
International 504 gasser I had was negative ground with a 12V generator.
I don't know a surefire way to tell, but am watching this thread. Always been curious if there is a method. I think on gassers you can check the coil wiring and that will tell you. |
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Central Illinois |
I'm thinking the battery terminals are different sizes.
The positive is a little bigger than the negative.
Maybe one of the clamps will be too small to fit over the positive terminal.
Edit: spelling
Edited by Ron (Cen. IL.) 2/22/2016 15:51
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| Yep, that's exactly how I would try to figure it out. Positive terminal is almost always bigger, hopefully the cable ends are still there. |
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Cleveland, MS. Own small farm near Booneville, MS | I would guess that someone over at Yesterday's Tractors would know. http://www.yesterdaystractors.com/ Edit: to correct link
Edited by clevepreach 2/22/2016 16:04
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London, Ontario |
That would be our daily user. 580b with a cab. Negative ground. 1975
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Mount Vernon, WA | USUALLY, a 6-volt system is positive ground, and a 12-volt system is negative ground, but not always. |
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central Indiana | bingo.... ron |
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Wisconsin | My way on the oliver 88 and such was only one thick heavy wire to starter was a positive ground. Other negetive ground ran a heavy ground to starter also but maybe that was unique to those olivers not sure. |
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| unhook the alt ,gen and hit the key
the starter will turn the proper way regardless |
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Wallis, TX | IIRC all alternator machines were negative ground. |
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Lincoln County. NC | Most 12V systems OTHER than Ford and using generators are positive ground. Includes Deere, Oliver, IH, AC. Can't say about Massy, but would bet they are included. |
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Statesville, NC | If you are really having to open up one clamp, and the other one just won't go closed enough, you are doing something wrong. Put it on where the clamps fit best. |
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Crawfordsville, Arkansas | pjjw - 2/22/2016 15:06
That would be our daily user. 580b with a cab. Negative ground. 1975
This one is a 580 CK from looking at some pics on Google.
The wiring is a mess on this thing. Years of shade tree backyard mechanic shortcuts, bypasses and rewiring. Pretty sure the cable ends are the same size but they look to have been replaced. I'll take a better light with me in the morning and look it over better.
There was a 12 volt battery laying under it so I assume it's 12 volt and someone has messed with it in the past and gave up.
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| Not true at all. My dad had Massey combines that had 12 volt generators and they were neg ground. Same with his 930 Case tractor;. |
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Lincoln County. NC | Sheep Herder - 2/22/2016 19:49
Not true at all. My dad had Massey combines that had 12 volt generators and they were neg ground. Same with his 930 Case tractor;.
Funny I didn't mention Case and pled ignorance about Massey. |
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Southwestern Ohio |
If Case ever used positive ground they didn't use many, a DC was negative ground. I am sure your backhoe is negative ground.
Larry
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Hagen Brothers farms,Goodrich ND | Gen or alt , 6V or 12V does not mean either pos or neg ground, their were many variations of each. Check stuff like cable end size, pos is larger. Connect a battery but do not start it, turn on ignition and working lights and or accessory if it has an ammeter. correct battery connections with an ammeter will indicate discharge with lights/ accessorues on.
Check alt / gen to see if they indicate pos or neg ground on case or tags (gen will charge either way depending on what it is polorized for.
Is there a backhoe of the same model / vintage in the area ? goi check it out. |
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Liberty, MO | 73 Freightliner, alternator positive ground, that for sure, it's mine, always have to stop and think when jumping. |
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| Not true. Until about 1960 the SAE standard for vehicle and tractor starting and electrical systems did not specify voltage or polarity. Fact is either polarity works with a generator, ignition coil is a bit picky about polarity and the ammeter fully picky about polarity. In the 30s some automotive engineers thought positive ground was better about erosion at connections to the frame and others thought the opposite, so both were used. Actually if direction of current a ground connections was a problem the different polarities would move the corrosion between load connections and the main battery ground cable connection. There still would be corrosion. Some of the arguments came from corrosion in DC trolley systems of underground water and gas pipes. And whether a particular ground connection corroded a pipe depended on whether the pipe was near the power substation or distant from the power substation.
Radios in the old days were sometimes polarity sensitive, but some simply (like Motorola, GE, and RCA two way) had a vibrator that could be turned around to adjust for polarity. That was tube radios. Reversed polarity kept the radio from working but didn't damage it. Solid state radios have no tolerance for reversed polarity, because it causes instant destruction. It is possible to protect but few makers have ever bothered. So about 1955 the SAE standard took out 6 volts as an option leaving 12 and 24 volts, but still didn't specify a ground. About 1960 that standard was modified to specify only negative ground with preference for 12 volts. A few years later it was modified again to only allow 24 volts for situations where 12 volts wouldn't crank a big engine.
Generators will charge with either polarity once flashed to set the building polarity. Alternators generally have to be rewired. I have a big Leece-Neville that can be wired for either polarity. Most Delco were negative ground though a manual I have shows positive ground alternators were a possibility. Just depends on the connections to the diodes inside the alternator. But the alternator is also as intolerant of reversed voltage as the solid state radio.
Then there were JD 24 volt diesel tractors in the 50s and 60 that actually had one each 12 volt positive and negative ground system with the charger and starter using the 24 volts, but all the other circuits for gauges and lights were 12 volts. Had to balance the positive and negative circuits to keep the battery charging even. For neophytes to electricity, these are difficult to understand, but not really different from the first 110/220 DC circuits used by the Edison Electric company in the 1890s.
Gerald J. |
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| The starter won't care. The ammeter and charging system will care. If its an alternator it will be very intolerant of reversed voltage. Reversed voltage will essentially short the battery and melt parts like diodes on the alternator. If its generator, either polarity will work so long as you flash the generator (jump the B to A terminals on the regulator for a couple seconds with the battery connected) before you try to start it. Even if you get the polarity right, a generator that has set for a decade needs to be flashed to make sure it build voltage and in the correct polarity. Flashing magnetizes the field poles to leave some residual to make the generator start building voltage when its running. Wrong polarity from the generator and destroy the cutout section of the voltage regulator.
You can test the alternator polarity (almost always negative ground, but not absolutely) with an ohmmeter that you know the polarity. One polarity of the ohmmeter the output of the alternator will show open and the other polarity it will show a couple silicon diode drops, so you want to use a range that shows diodes. A simpler test takes a battery and a test light. Start by connecting one battery post to ground then hook the test light between the other battery post and the other battery cable. With all load switches off, the test light will glow full brilliance if the battery polarity is backwards but won't light at all if the battery polarity is correct.
If you were to wait until you got an official shop manual and repaired the cobbled wiring you might save much work and damaged parts.
Gerald J. |
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Positive or negative ground? How to tell?
