12 volt battery on OC3

[jr/w.pa]

I recently got an OC3 with an alternator and 12 volt battery. Due to the bad winter,I tarped it until the weather warmed up enough to work on it. The battery was dead and would not take a charge. To be sure, I had it tested at a NAPA parts store. They said the battery was toast. The battery was was attached in this manner with the negative terminal going to the starter and the positive going to the ground. I know that 6 volt systems are connected this way but should a 12 volt system with an alternator be connected in this manner or should it be positive to the starter switch and a negative ground.Before putting in a new 12 volt battery ,I would appreciate some advice on which way to attach the battery to the cables.

[coffeecreek]

Well the knee jerk reaction is no , alternators are negative ground . The correct answer is , you will have to do some investigating . It is possible to purchase a positive ground alternator .  It is also possible to purchase a 6 volt alternator in either positive , or negative ground . ( I have a positive ground 6 volt alternator on a Model A Ford right now ) . Hopefully it will be marked on the alternator .

[hotratz]

Hook it up negative ground. The starter won't care. It will turn the correct direction regardless unless it is a permanent magnet field. Just make sure the +plus on the alternator is also going to the +plus on the battery also. Either system will work the same as long as you haven't crossed polarity on anything. Neg. ground is just more conventional these days.

[440roadrunner]

The correct answer is , you will have to do some investigating . It is possible to purchase a positive ground alternator .  It is also possible to purchase a 6 volt alternator in either positive , or negative ground . ( I have a positive ground 6 volt alternator on a Model A Ford right now ) . Hopefully it will be marked on the alternator .

THIS IS  the correct answer.    A  good example  was  the older  Delco / Mopar  (don't know about Ferds)  back when they had individual  diodes  instead of a  bridge.    It was  an easy  afternoon job  to remove all six  diodes,   swap  their positions,  and you have  a  POS  ground alternator

There DOES  exist  some  heavy trucks that were  POS  ground  12V.   What  a PITA  to get  2-way  radios  working in them!!!!

You can  easily  figure this out.   Get a charged battery,   and do NOT hook up  the "hot"  lead.    Ground   say,  the NEG  (you have  a 99%  - 1%  shot, LOL)  and then  take a test lamp and wire  IN SERIES  with the positive post to the hot  stud  on the alternator.  Do this with  the main  charge wire  to the alternator  unhooked

If you do NOT   get a  light, you have the polarity reversed.      If you DO  get a light, the battery is backwards

To make this even more  convoluted,    sometimes  "back in the day"   either dry-charged  "new"  batteries    or   batteries  which  had been run  completely  dead    somehow  got  "Reverse"  charged.   So you could NOT  go  by  battery  post markings.      In my  66  years,   I've run into this at least  twice.

[coffeecreek]

If you do NOT   get a  light, you have the polarity reversed.      If you DO  get a light, the battery is backwards

Thank you for explaining  . This line confused me though . I'm reading it as " polarity reversed " and " battery backward " as the same thing ?  Did I miss something ? Seriously , it's been a long day and I ain't feeling too smart right now , so if I'm being an idiot , say so .