Okay im mega confused. When i moved my battery from the engine bay to the trunk of my car i just took the wire that was spliced into the main battery wire (this is the charging wire from the alt) and ran it to the battery in the back of the car.

Well i was just looking at that wire today and i actually followed it back to the alternator and i dont get how the heck it charges my battery. It attaches to the alternator in the same way that the ground does just a metal connection thats bolted to the back of it. How the heck does that actually charge the battery? if i touched it while the car was running would i get shocked? (if i was grounded)

 

This wire is attached to the out put terminal on the alternator and is puting out somewhere around 13.5 to 14 volts. And yes you will get a good shock. Test it with a multimeter or test light. This is quite a bit longer run then stock so I would recommend that you increase the wire gage by one size. If it's a 14 gage wire go to a 12ga., if it's 12ga. go to a 10ga.

 

You shouldn't get a shock since it's low voltage dc. If you get a shock, one of the rectifiers might be bad. Alternators are ac generators. They have rectifiers to convert this to dc.

If you eyeball the stud where wire connects at back of alternator, you will see it is insulated from case. Voltage at this point should not differ from voltage at battery + by more than a fraction of a volt (voltage drop). I soldered all the terminal/wire crimps on my 71 when I put the battery in the boot and got the drop down to .2 volts.

 

No shock? Your battery is ONLY 12V, thats low by your standard. Go ahead and grab the battery terminals. And let us know if you get a shock or not.

 

Done it before, never gotten shocked.

Dry body resistance is usually a minimum of 1 mega ohms. 12v/1 M ohm = 12 micro amps. Generally accepted that 5 milliamp is the threshold of perception, shock around 50 milliamps. That's with dc, 60 hz ac is lower, high frequency ac is about the same as dc.

If you were really sweaty, had a metal object in your hand, and had good contact to ground, cross body resistance could drop to 1 kilo ohm. 12v/1 k ohm = 12 milliamp. This crosses the threshold of perception, but not shock.

But it would cross the shock minimum (~9-10 milliamp) for 60 hz ac. This is why I said that he shouldn't feel a shock UNLESS one of the rectifiers was shorted and strapping unrectified ac to the charging system.

But this is all theory, so out of curiosity, I fired up the 71, grounded my left hand, and put my finger on the output stud of the alternator. Zip. Repeated with wet fingers. Zip. Same exercise grabbing the + and - directly at the battery, also = zip.

So if you are feeling a shock, something is wrong, disassemble your alternator and ohm out the rectifiers, one is probably shorted. I remember a friend with a Nova doing the "disconnect the positive cable with the engine running to see if the alternator is charging" trick (bad thing to do, btw). When he would get the cable about 1/8" from the + terminal, you could see sparks jumping the gap. We checked his rectifiers, and sure enough, 2 were shorted. This was an old style alternator with discrete rectifiers, new alternators come with integrated rectifiers.

 

wow angel71 i dunno as much about electrics as u do i guess, u seem to have ur stats down well. i'll take ur word on toching wires and terminals. Doug i would go with a volt light b4 touching anything.

p.s. angel if your every near chicago street racing or any local tracks (wis. area) drop me a pm. i'm sure i can get a alotta peeps to throw down some money (myself included) to see you grab 2 battery termials!!!