Ok here is the deal last week my battery kept dying or just held enough charge to barely start my car so i went out and bought a brand new battery,but i had my lil bro install it in which he hooked up the negative to the positive of the battery so i corrected this prob. and tried to start my car in which i found he blew the ignition & alternator fuse >i replaced both fuses< and my car started straight up with good RPM's but on my way home from my bros house my lights,radio,clock became dim as if my battery were dying so the next morning i used my digital multimeter to check the voltage in my battery and it was 11.45 volts so i tried to start my car and it acted as if the battery were dead so what could be the problem????????is it the battery,alternator,or something else ????please help

 

Did you check igntion switch?

 

Sounds like you might have fried the alternator. Start your vehicle and put the multi meter on the battery and check to see if you got power going back into the battery. You should be over 13 volts

 

It sounds like the alternator, or a fuse, or a fusible link in the wiring harness.