parasitic drain
Thread Starter
Instructor
Joined: Jan 2012
Posts: 215
Likes: 6
From: Mebane, NC
parasitic drain
Nieghbor has a '69 with a 327. Hasn't driven it in a couple years because he could not keep the battery charged. He thinks the drain is in the alternator because it seems to eat voltage regulators.
What should he be looking for? Also can the voltage regulator be bench tested or must it be on the car?
What should he be looking for? Also can the voltage regulator be bench tested or must it be on the car?
Melting Slicks
Joined: Apr 2009
Posts: 2,632
Likes: 112
From: Great Plains Iowa
Nieghbor has a '69 with a 327. Hasn't driven it in a couple years because he could not keep the battery charged. He thinks the drain is in the alternator because it seems to eat voltage regulators.
What should he be looking for? Also can the voltage regulator be bench tested or must it be on the car?
What should he be looking for? Also can the voltage regulator be bench tested or must it be on the car?
If his alternator has a rear 2-terminal plugin it has an external voltage regulator. If it has a side 2-terminal plugin it has an internal voltage regulator. Find out which style it has so we can better answer your question.
Burning Brakes
Joined: Jan 2012
Posts: 943
Likes: 73
Nieghbor has a '69 with a 327. Hasn't driven it in a couple years because he could not keep the battery charged. He thinks the drain is in the alternator because it seems to eat voltage regulators.
What should he be looking for? Also can the voltage regulator be bench tested or must it be on the car?
What should he be looking for? Also can the voltage regulator be bench tested or must it be on the car?
Thread Starter
Instructor
Joined: Jan 2012
Posts: 215
Likes: 6
From: Mebane, NC
He says it is a standard GM alternator. Internal regulated through a two wire plug on the side of the case, ground wire and hot wire. The battery will take and hold a full charge when a battery charger is used.
Melting Slicks
Joined: Apr 2009
Posts: 2,632
Likes: 112
From: Great Plains Iowa
If the alternator's field is being energized the rear bearing will be a powerful magnet; able to stick a 16-penny nail to it. Also the small wire on the side plugin should be dead when the key is OFF.
Burning Brakes
Joined: Jan 2012
Posts: 943
Likes: 73
Do you have access or own a clamp on type amp meter?
Burning Brakes
Joined: Jan 2012
Posts: 943
Likes: 73
Good deal on the amp meter, not many have one. The voltage (pressure) may be there, but not the flow. I also had a parasitic draw that I tracked down to the alternator/regulator on my 80. I replaced the alternator and eliminated the draw. After the engine starts, the alternator output needs to settle down to probably less than 10 amps, unless the cooling fan is on. One possible cause of a high amp output (battery fully charged) is the internal resistance of the battery. That resistance could be burning up the alternator/regulator by demanding constant high output. Hopefully that's not it.
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