When I put the ground wire on the battery I get a hot spark. Ignition key is off, I checked the red wire going to the alternator and has a spark whenever the ground wire is hooked to the battery with the key off. The car is a 67 cutlass. What should I check next? Thanks.

 

Do you have any aftermarket items installed that could draw power with the key off, ie digital stereo, alarm, etc... Was a door open and courtesy lights on, glove box light, under hood or trunk light?

 

No nothing after market. The spark was hot enough to almost melt the battery terminal. After I removed the red wire from the alternator, no spark at the battery terminal. Thanks

 

You may have a bad alternator, diodes. Get it checked with the voltage regulator if you still have an external.

 

Assuming you have a bone stock car, there should be a tiny spark as the hood light lights up and the clock lurches into motion. If you're getting serious spark, something is afoot, and do like the man above said.

 

X2 bad alt without doubt. Repair or replace. Keep battery disconnected until repair.

 

Old age kicking in again, I had the red wire hooked to the wrong terminal on the alternator. Thanks for your help.

 

Or that...