when the headlights are turned on the amp gauge starts to fall from around 12.5 down around 8 I replaced the battery and the alternator sill draining the battery took the alternator back thinking it could be bad still having the problem. what could be draining the battery when the headlights are turned on?

 

Are you using a volt meter or looking at the volt gauge in the dash? Do you have under drive pulleys?

 

I used a volt meter just to check the state of the battery, I didn't change anything other than a new battery, and the alternator. I know that if i drive the car with the lights on it will kill the battery.

 

post what volt readings you got from your DVM.
battery with everything off=
battery with car running=
battery with car running and headlights on=

 

you should perform a voltage drop test also. directions in this link;
http://forums.hotrod.com/circle-trac...your-race-car/

 

I checked the volts today, car off-11.8, car running-12.4, car running lights on 11.4

 

all low numbers. fully charged battery at rest should be around 12.6. it sounds like your alternator might not be charging. try hooking up your DVM from negative battery post, to the positive battery terminal on the alternator. sound be around 13.5-14.7 if the alternator is charging. sometimes those 10 gauge wires from the back of the alternator to battery positive post go bad. its ok to add a 2nd 10 gauge wire if needed. just need to verify that the alternator is charging at that post.

 

What year is the car?

When you turn the key to On with the engine not running, does the Alt light come on? (might be labeled "Choke" instead of something electrical)

 

went out today , was going to try and test the problem more dead battery. so what is draining the battery. new napa battery new alternator from napa.

 

It should have a little red battery that lights up on the dash. If it's out it may not complete a circuit the alt is looking for to start charging.