Guessing and shotgunning parts at a problem is not the best way to resolve an electrical problem. A fully charged battery should have about 12.5 volts at the posts before starting the engine, and if the alternator is functioning properly, the voltage should be between 13 and 14.5 volts. It sounds like you've had another alternator failure, or something is wrong with the way the charging circuit is wired. Are you running a so-called "1-wire" setup? (which actually requires the use of two wires)?
Jerry
