# positive grounding on old oliver



## formulamx91 (Apr 3, 2009)

Might seem like a silly question but how do you hook u a electric battery charger to a positive ground tractor


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## Live Oak (Dec 22, 2003)

Welcome to Tractor Forum formulamx91! 

Hook the allegator + or - clips from the charger to the corresponding + or - terminal on the battery. That way as far as the battery, charger, and system sees, it is apple and apples.

It is best to charge the battery with the tractor battery cable leads disconnected from the battery. That way you are sure to be charging ONLY the battery and no other equippment left on drawing power or a possible short in the system.


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## formulamx91 (Apr 3, 2009)

Then how does the battery get charged when it is running?


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## Live Oak (Dec 22, 2003)

Positive ground charging systems run current in the reverse of negative ground systems.


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## k1burner (Mar 26, 2009)

maybe a little simple but here goes my laymen terms of understanding........

DC electricity want to go on a path from the + terminal to the Negative terminal, hopefully while on this path doing some work for us, (fan, light, starter etc..).

With a negative ground system the + terminal is isolated from the tractor and a wire brings the current through to the "device" where the electricity does the work and then returns to the - terminal through the tractor, hence the reason the Negative terminal is "grounded" to the tractor.

With a Postive ground the negative terminal is isolated from the tractor and current is sent through the tractor and is isolated back to the negative terminal through wires.

Positive ground.... + Cable to the + terminal or to the tractor itself and negative to the - "negative terminal"

I hope that made it as clear as mud


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## jetdog (Jan 20, 2010)

*Reverse Polarity*

We have an old 1958 Mack B-85 (505-cid Gasoline) with a Reverse Current Electrical System. We ALWAYS disconnect the battery when charging, that way you can simply charge the battery as you normally would (red-positive/black-negative). But once on the equipment, your right, the current runs backwards. One thing to remember with these old systems.....be careful in adding newer "solid-state" electronics like radios, etc.,.....the reverse current will usually blow them up! We had 2 old green/white Olivers, back in the '70s but can remember the charging system. But the Mack that has a Reverse Current System utilizes a Generator producing "wild" 3-phase A/C currents which then go into a big Transformer-Rectifier which produces the D/C current to the truck. I had to replace the T/R one time and it was really difficult to find, and that was all that really wanted to mess with, considering my limit knowledge. But Reverse Current systems are interesting nevertheless! Jetdog


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## George G (Feb 12, 2005)

> _Originally posted by k1burner _
> *
> 
> DC electricity want to go on a path from the + terminal to the Negative terminal, hopefully while on this path doing some work for us, (fan, light, starter etc..).
> *


All good,execpt, DC flows from - to +.


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