Another Electrical ques.
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Another Electrical ques.
Im not very good with electrical systems and this might sound like a dumb question. Just got my 78 up and running again and I know while running if the battery post is disconnected and the truck cuts off you have a alternator issue right? Well my, what I call a problem, is that while idleing when I pull the positive post of the motor actually clears up and runs smoother. When I hook it back up it drops about 200 rpm and runs rough. Whats goin on?
Save the old ones
Joined: Dec 2002
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From: Boyne Mich
I think your idle goes down when you connect it back to the battery because your altenator is working. I have seen this before when jump starting another vehicle. When you hook up the last connection on the jumper cable the running vehicle will tend to load a little trying to charge the other battery.(slower idle or work a little harder)
I agree I would not recommend disconnecting a cable while it is running. It is probably safer with some of the older cars, but the newer electronic stuff could be costly.
Best thing is to have a clamp on AMP meter. Or just as well is a plain old volt meter.
The volt meter should read 12 to 12-1/2 volts (at battery) when truck is off and 13 to 14 volts running. If so, Altenator is working. If the voltage is the same when running and when turned off - say 11-1/2 volts you have problems.
Shawn
I agree I would not recommend disconnecting a cable while it is running. It is probably safer with some of the older cars, but the newer electronic stuff could be costly.
Best thing is to have a clamp on AMP meter. Or just as well is a plain old volt meter.
The volt meter should read 12 to 12-1/2 volts (at battery) when truck is off and 13 to 14 volts running. If so, Altenator is working. If the voltage is the same when running and when turned off - say 11-1/2 volts you have problems.
Shawn
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Joined: Aug 2003
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From: Crestline, California
I am sure that Dennis will correct me if I am wrong, but my understanding is that, while running the engine will continue to pull from the battery when you disconnect the alternator. When you re-connect it, perhaps the reason that the rpms drop is a surge of pull from the alternator to recharge the battery that was being drained while the alternator was disconnected. Dennis?...
Dak
Dak
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Dave in the electrical forum is a better explainer of this.
The thing is ..It shouldn't EVER be done unless one is rich and like to buy alternators.
It blows diodes .....from the surge of reconnection.
Basical info !
The power that the alternator is producing has to "Go somewhere"
It should never be disconnected while the engine is running ....Period.
In the days of generators doing what he describes was to EXCITE the new generator to begin charging .....if it wasn't already.
Alternators don't require this
The thing is ..It shouldn't EVER be done unless one is rich and like to buy alternators.
It blows diodes .....from the surge of reconnection.
Basical info !
The power that the alternator is producing has to "Go somewhere"
It should never be disconnected while the engine is running ....Period.
In the days of generators doing what he describes was to EXCITE the new generator to begin charging .....if it wasn't already.
Alternators don't require this
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