neg cable off, car dies.

canadianstang · 04-02-2005

hi, on my 68 the car dies when i take the negative cable off the battery. the battery doesn't die if left overnight and restarts the car when i leave it running instead of dying on me so i'm pretty happy hehe. i put a new voltage regulator on and that fixed my battery charging problem (thought that was the last thing that woulda been wrong since the voltage reg looked brand new). i know theres some screwy wiring still but was gonna wait and save up for another harness or get one at carlisle hopefully. thanks

Quick66 · 04-03-2005

I am pretty positive that the primary circuit(12v)of your car is straight polarity, which means that the flow of electrons is from + to -.That being said. if your alternator is putting out a charge and you remove the ground path to the battery then you are in effect opening all circuits in the primary. The alternator is putting out the positive charge, but you have removed the negativly charged portion of the circuit.What I'm trying to say is that the car should die when the negative cable is removed from the battery. It should also continue to run if the positive cable only is removed.By the way this is also the way every switch in the primary circuit should operate( by removing the path to ground)

canadianstang · 04-03-2005

cool i'll give it a try. thanks

Acooljt · 04-06-2005

Yes, all circuits in a car are DC(direct current) and if you take either of your battery cables off, it will kill the motor. Reason being is that all electrical circuits must be in a complete loop. When you disconnect that cable, it puts a break in the circuit, thus killing your car.

Quick66 · 04-07-2005

while you and I may agree on the polarity and classification of an automobile's primary and secondary ignition system we don't agree on the function of the battery and alternator obviously. What I said in my initial response was that the primary electrical system needs the ground (negative) side of the battery to be tied in with it so that there is a negative charge for the positive charge of the alternator to flow to. Because the end result of the alternator's operation is to saturate the the cars electrical system with an overabundance of electrons(DC +) then there need be a negative field for this current to flow to.If the alternator is charging the chassis electrical, then there need not be a positive charge source from the battery.THe only way to start the charge from the alternator is to turn it at high speeds .This is where the positive side of the battery comes in because you need the DC+ to start the car, thus turn the alternator. If your car had a strap connecting it to a source of ground, and you could start it with a handcrank, then you would not need a battery period as long as your alternator was supplying the DC+.A DC+ current will always look to equalize the difference in potential by the shortest path possible, which can be any conductor attached to a source with a more negative charge than itself

Quote:

Originally Posted by Acooljt

Yes, all circuits in a car are DC(direct current) and if you take either of your battery cables off, it will kill the motor. Reason being is that all electrical circuits must be in a complete loop. When you disconnect that cable, it puts a break in the circuit, thus killing your car.

merlynr · 04-07-2005

I thought an alternator had to have an "excitor current from a battery in order to charge. Can you push start (provided it's a stick shift) a car with a completely discharged (no life)battery and a good alternator?

canadianstang · 04-07-2005

i had though that the battery was just kinda inline with the alternator circuit. when the car started it was kinda out of the systemor useless jsut getting the 12 or 13 volts to keep it fully charged. cuz i'm almost positive that we had run my cousins camaro without a battery and it only died when i pulled the lights on. i do know thats hard on the alternator lol. and i agree how can u bum start a standard car with a dead battery? i've had to do that lotsa times. i don't know much about electricity so just askin. thanks

Tominator · 04-07-2005

Another mechanics 'old wives tale' exposed!

When you interrupt the circuit to the battery by taking off a cable, you cause the alternator to put out MAXIMUM capacity! Unless the alternator is PERFECT, and few are, it will blow a diode .

Then you will rack your brain on why your battery keeps draing. No idiot light. Even if your gage shows charge the recovery time will be drastically extended.

Only IDIOTS remove a battery cable with the car running.

canadianstang · 04-07-2005

hmmm i guess i am an idiot thats why i try to get information from geniuses like you tominator, to try and better myself hahaha

. thanks i fooled around with the wiring and the battery doesn't die now but am still gonna take it to the guy that rebuilt the alt he does all kinds of wiring things jsut to make sure its all working correctly. i'm not very good at wiring and just try to get as much info about things as possible for the next time hehe.

Tominator · 04-08-2005

I'm no genius!

Anyone with the least bit of understanding about chargeing systems knows NEVEr to do that.

I've found there are more than a few ASE Certified mechanics that know only enough to be dangerous and I did not mean to infer you were THE idiot.

There are just TOO many mechanics wandering about that use that very method to 'check out' whether the alternator is working.

Sorry to be offensive. :o

Acooljt · 04-09-2005

Yeah, I looked into getting ASE certified at one time, and it doesn't take much.