freshly charged battery

[bulleteater]

Hi guys!
What do you think? I had a fully charged battery at least enough to start my car, well it was running so I thought I would adjust my carb because of another issue but anyway I tuned it where it sounded good or so I thought. Well for s#$ts and grins I put my car in reverse and 2 sec later my cars tach read negative and then my car died! Now when I say died I mean completely dead to where I had to throw my jump starter on to crank it over.. Well it started OK so I checked the battery with a dmm and I was drawing  13.5-13.75 and it wasn't dropping below those readings so I decided to put my car into gear and again my car died and the battery was reading about 10 volts and continued to go down which tells me the new battery may be toast but I thought I would jump it again and check the dmm again and it read  13.5-13.75 and again I put my car in gear and same problem..
So.. I don't know maybe the voltage regulator?

[A383Wing]

voltage regulator seems fine, all it does is tell the alternator how much to charge the battery...sounds like you got a dead cell or 2 in the battery.....take it out and have it tested somewhere to be sure....

or turn lights on for a couple minutes, then turn off, disconnect battery cable, and measure voltage at battery terminals and see what it reads

[b5blue]

A DMM is not going to tell you much about your battery. It needs a true conductive test to tell if the CA's are pooched. 
  https://www.youtube.com/watch?v=Oi8sUE9XCgA

[bulleteater]

Hey thanks guys! I will take it to the nearest parts store.. But I guess I don't understand if the alternator is working just fine why would my car just die after putting it in gear? I don't know I guess I've always felt my car in an enigma haha