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.
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 .
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.
Quote from: coffeecreek on April 19, 2014, 02:18:19 AM
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.
Quote from: 440roadrunner on June 22, 2014, 04:45:12 AM
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 . :)