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SAE on battery polarity and its history

A

Anonymous-0

Well-known Member
I had a little time at the university library last week. I found:

Since 1963, SAE standard J543a has stated "the negative terminal of the battery shall be securely grounded." Before that from a committee report in 1955 that new standard J543a stated "The negative terminal of the battery should be grounded." So before 1955 polarity was optional. From 1955 it was recommended the negative post should be grounded, and from 1963 the standard required the negative terminal to be grounded, though it took until at least 1969 for Deere to follow that standard in gas tractors.

Gerald J.
 
No doubt the SAE standard was in 1963. if you changed models you would update to a negative ground. I also remember a man form the Oliver plant in the summer of 1964 visting our place and he told me the new Oliver 50 series which were ready to be introduced would have negative ground and the goverment was pushing it to happen because of some radio interference and to make sure all the equipment was grounded the same way. Appreciate your comments.
 
in the late 70's I worked in a fleet truck shop. We had a mid 70's Freightliner that was positive ground.
Tim in OR
 
Negative ground simplifies alternator and radio stocking. Solid state regulators, rectifiers, and radios absolutely can't tolerate reversed voltage for even a microsecond. "Lets the smoke out." Burns things to a crisp inside the solid state devices, sometimes outside.

Before the negative ground situation became SOP, radios often came with polarity switching plugs, whether for broadcast or two way.

Certainly using both polarities on different equipment added complication and yet 30 or 40 years (as of 1955) of experience hadn't shown any benefit of positive or negative ground over the other polarity. But to the less experienced person troubleshooting, positive ground causes much confusion, even today. And can get you into deep trouble when jump starting.

In my reading of SAE handbooks, I didn't detect a government requirement, just the results of an SAE study committee. Though in looking on line for J543a, I have come upon government standards relying on it and requiring negative ground.

Gerald J.
 
Wasn't really necessary until charging systems using semi-conducters came into common public use.

Anything SAE says is just a suggestion from one group, anyway, just like National Electrical Code. Nobody has to take any of their suggestions, unless a locality makes it law. I think some people confuse what is legally mandated, versus what some organization "suggests."

Positive ground is still used in new equipment, as well as some postive ground alternators. Especially in some large marine systems, where there are some benefits to using postive ground over negative.
 
Before the SAE standard J543a the automotive, truck, and tractor world was pretty much evenly split between positive and negative ground, generally by manufacturer. In the 1930s there were arguments put out by the different factions justifying their choices.

Its kind of like which side of the road to drive on. So long as you are alone, either side gets you to your destination safely, but if you have to share it works a whole lot better if all follow the same rule.

Gerald J.
 
I call that progress.. When jump starting one assumes all are equal without ever looking.You have woke me up.
 
In one of the many Case books . they mentioned that Racine used positive ground while the Rock Island plant was negative ground on the same tractors !! You realy had to watch out for them !!
 
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