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Discussion Starter #1
I have a 72 Nova with an alternator with an internal regulator. The battery and alternator are brand new and work properly. However a couple weeks ago one of the ground wires from the negative terminal on the battery became hot and melted it's covering. After that the battery wiould not charge while the engines running. i can charge it with an external battery charger. Any ideas? Everyone I've talked to is stumped
 

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kman723 said:
I have a 72 Nova with an alternator with an internal regulator. The battery and alternator are brand new and work properly. However a couple weeks ago one of the ground wires from the negative terminal on the battery became hot and melted it's covering. After that the battery wiould not charge while the engines running. i can charge it with an external battery charger. Any ideas? Everyone I've talked to is stumped
What caused the cable to become hot and melt...a dead short somewhere??? You changed the battery cable after that right? Also how do you know that the battery is being charged by the charger? Not trying to ask some stupid questions here.
 

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Welcome Kman!

72's had external regulators FWIW. Did you switch to an internal regulator alternator? If you just did, did you disconnect the external reg and properly run new wiring to the internal alternator?

Other than that, if everything was charging O.K. up until this latest problem, I'd suspect that the alternator is now defective. Pull it and have it tested (a freebie) or just buy a new one. They're pretty cheap.
 

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Discussion Starter #4
couldn't figure out what caused the hot wire. But I did replace the cables. The previous owner switched to a newer style alternator with an internal regulator. The alternator is brand new and has been tested twice.
 

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kman723 said:
couldn't figure out what caused the hot wire. But I did replace the cables. The previous owner switched to a newer style alternator with an internal regulator. The alternator is brand new and has been tested twice.
I would use a meter connected right at the posts of the battery and see where the battery voltage is at with the key off and then when it's started. I normally like to see 1V or more difference with an engine running voltage of 13.5V to 14.5V. With the key off maybe 11.5V-12.5V.
If you get the higher voltage when the engine is running the alternator should be fine so what could be bad is the battery. I just went a round with an Optima battery in a vehicle and it turned out the battery was bad.
If you have had the alternator tested and have new cables going between the engine and the battery then unless something is wired wrong bypassing the old regulators wiring then I would think a battery problem.


What probably smoked or melted the one small wire off of the battery negative terminal was either poor connections or excessive current. Normally you have off of the battery negative terminal two wires (one large that goes to the block and a second smaller one to the fender or radiator support). If the large one connected to the block has a poor connection to the motor or on the end by the battery then the small wire is trying to pick up the slack and with it being small cannot handle it so the insulation melts off of it. If the small wire has a connection problem the car may crank over and run fine but things like the headlights may not burn bright or the blower motors speed may be slower than normal as those things grounded to the chassis or body of the car are trying to find a ground through other components.

Jim
 

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Discussion Starter #7
ok, after countless hours of troubleshooting I've figured out that the alternator isn't putting out enough V. while the car is running. I've had the alternator tested twice and both times it came back with 14.35v on the test machine. But when I put it in the nova it only puts out like 3.25v. Even when i hit the accelerator. Any ideas?
 

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Check all of your alternator connections again. Look for burnt or corroded plugs and connectors. Is the battery ground connection properly bolted to the ENGINE? Do you have engine to frame and / or firewall GROUND straps in place with good connection?

If all that checks out, I'd assume that you are mis-wired OR the alt is at fault with internal problems.

If you place a meter on the battery posts, what voltage do you read running and sitting w/the engine turned off?
 

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Discussion Starter #10
ok, I checked all the connections, replaced the alternator connectors, checked the grounds. all check out. I get 13.4v from the battery while off. Anyone have a good link so I can check the right way this should be wired. The previous owner took a lot of short cuts, and I think that's one of my biggest problems right now.

And thanks to everyone here, this site is a great resource.
 

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Discussion Starter #14
well, I've installed a new battery ran new grounds for the battery and engine(since there wasn't one before) and replaced all alterator and battery wires and connections. I've studied all the various wiring diagrams compared them to my wiring setup and still am not getting any juice out of the alternator. There's no change between the engine being on or off. it's a 10SI 63 amp alternator which should be plenty since I'm not running anything else right now. Any suggestions would be greatly appreciated
 

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Discussion Starter #15
Just remembered that when I raise the RPMs the idiot light starts to glow faintly. This give anyone any thoughts?
 

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I'm gonna take a blind shot here, but could this be a grounding issue for the alternator itself?

Does the alternator case need to be grounded properly for it to work properly? If your alt. mounting brackets are isolating it from the engine as a ground source, could that affect it's charging?
 

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Another blind shot...are you SURE that the new ALT is of the internally regulated type? (it will take a different style plug from the original externally regulated unit 72').
 
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