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TO 20, polarity

C

CKain(MI)

Well-known Member
A friend has a 'project' 1950 TO20. Has no battery and has a alternator. Would it still be a positive ground ?
My thinking is mosty Alt's are negative gnd. Thanks
 

If it has an alternator first guess would be that it should be 12 volt negative ground. What alternator is it? Positive and negative battery posts are different sizes. If it has post type battery battery cable ends is the smaller one or larger one hooked to ground? The smaller post is negative.

There were/are some positive ground alternators but not common, as far as I know, and likely more expensive.
 
Thanks Jim, The battery cables are newly installed. Probably installed same as old one,, which Can be wrong now. It is a new 12v battery, wired positive ground ! Now then, the coil is wired neg. ground ! I know the spark plugs will spark either way.
The engine does start and run. I've only ran it twice, for a couple minutes. Was working on accelator rod & governor linkage.
If the alternator is a normal neg grnd, it will not be charging....next thing to check out ! It is a Delco but I cannot see
a number, on visible side.
 
Very, very slim chance it is a positive ground alternator.

Either the battery is charged backward, or the diodes in the alternator are blown open, or the battery connection to the alternator is open.

If the alternator is somehow charging, check the polarity with a volt meter. Once a battery has been fully discharged it is possible to charge it backward.

If the polarity were reversed you would have known it, there would have been a huge spark when the battery was connected and the wire to the alternator would have smoked!
 
yes,back in the 60's I was a tech at a radio/tv shop. A girl brought in her car, said she just got it back from the dearler and radio wont work. they sent her to our shop. I put a meter on the hot wire, it was -12, battery was charged backwards !
I sent her back to the dealer. ;)
 
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