Just recently got a new battery and alternator after my mom said it had died on her while i was on vacation.

Started it up, drove around my block a few times and the volts dived down below red.

Could it be something between the alt and battery? Or did i get a bad alt?

 

either a short or bad alternator. unhook the positve cable from batter and check to see if it shows as being grounded. use ohm meter. check with key off and key on.

 

Check your field wire going to the alternator. GM alternators are excited by a field wire. When you start the car the field wire sends voltage to the alternator for a brief moment, then the alternator starts charging. Get an olmsmeter and check the power feed on the alternator, let me know what you find.

 

I believe the best troubleshooting trick is pull a battery cable of and insert a light bulb, any 12 volt light bulb, 61 or a 63, 1156, between the cable and post.
Being the Camaro has an ECM and electronic radio, the bulb should glow dimly as both unit are drawing some current for their memory.

A bright bulb means a major current flow and pulling fuses one at a time, and observe the glow, can point to the faulty circuit. If you get to the end of fuses, and still bright, you might unhook the alternator ensuring it can be or cannot be the culprit.

Also, if a new battery, you may need to give it a slow overnight charge for completely charging it.

Your alternator has an internal regulator and it may have decided to take a different route than you wanted it to do.

You can always take it back to the local parts store and have them test the alternator either on their machine, or if bought from Advance, take the car to them and let them check the charging system for free.

The light trick works. If you are down to the ECM and radio, pull the fuses. With all fuses out, and any aftermarket installed accessories disconnected, the bulb should be dark. At a min, if you have a dim glow, you can insert your test meter as a current meter, ammeter, and measure the quiet current, car at rest. It should indicate no more than 50 milliamperes, 0.050 amps.

 

Good troubleshooting sequence and very thorough.

However, back to the original poster, since you just replaced the alternator, the most likely suspect is a bad one out of the box. Unless you somehow hooked it up wrong, which would take some doing, but could be done.

Take the alternator back and have it tested. If it is good, then check your battery cables to make sure the hot lead is not damaged or pinched somewhere.

 

If it was parasitic draw the car wouldnt drop voltage like that while driving, it would just drain while the car sat and you would likely experience slow cranking or no cranking. I would go over all the connections for the alt and battery by voltage drop testing. Shouldnt see more than .2-.3 volt drop on ground connections and .5 volt on hot side connections. If you find no excessive drops make sure all the alternator bolts are tight i replaced mine and one came loose creating a similar issue. i would also wiggle test the field wires that are in the connector for the alt to see if they have an open or something. If that fails to find a fault i would suspect the alternator is bad out of the box. May have overheating diodes that fail when the engine warms up and they get hot or something else like that. I've tested alternators that have a bad diode that will put out a decent charging voltage but obviously showed an open diode on an oscilliscope, which was causing slow cranking issues or dimmer than normal lights.