Constant Charging Light

[dane trSix <dbtr6@yahoo.com>]

Could someone please tell me where I should start looking. The charging
light is on constantly, and the volt meter is showing almost 15 at
normal speed, and 12 when I'm driving slow. All the other electical on
the car seem to be working fine. My battery has been discharged (almost
empty) a couple of time lately (forgot to turn off the radio), and I
borrowed a good one from my Jeep, but the charging light is still on. 

My car is a 73 tr6.

Thanks,
Dane