Just got 1966 mustang with 302 v/8 . Went to unload off truck would not start battery was completely dead.Guy had drove it on hauler 10 hours later dead. Put another battery on fired up went back to start 2 hours later dead. Alt was making some noise replaced charged batt. started. 2 hrs. later dead. Cant hear anything running but if you charge batt. and just hook cables up its running battery down just sitting. Any ideals would be appreciated. thanks Steve

 

If the battery is running down that fast you have a serious short somewhere.

 

some type of current drain. maybe from a small light being stuck on.

check it out in the dark and see if you find any lights or instruments that are running with the key out.

A amp draw test would be great idea. If you have multi meter place remove the + wire from battery and place one test lead on post and one test lead on the wire you removed and see what the current draw is.

-Gun

 

I'd replace the voltage regulator... only like $10 and mine was the source of my drain

 

definitely a large drain. perform the current draw test as Gun stated, just be sure the engine is off, with a ammeter (anything above .5 amp would be excessive). using a voltmeter, reconnect the battery, and put the positive lead to the backside of the alternator (in parallel now) with the negative lead on the neg. battery post- this will ensure that your alternator is charging (voltage should be at least 13.5V)

just fyi, I've had brand new voltage regulator be defective right out of the box- damn third world electronics.

 

That's why you don't buy the $10 POS voltage regulator, you buy the pricier one at Napa that will actually work and keep working. Still made in the US.

 

I have a $30 VR, I was just saying, to replace one from NPD or something is only $10 and a good way to know if it's your problem.

 

I don't believe in buying cheap electronics There really is a difference between the cheapo units and the expensive Echlin units that Napa carries.