Positive ground alternators are available, but they're scarce and expensive. Since practically everything produced since 1957 is 12V negative ground, there's no sense in trying to rig up a positive ground system, IMHO. You might have a shorted voltage regulator that's overcharging the battery. Max voltage against a well-charged battery should be around 14.7 volts. Higher than that, and you'll boil the battery dry, and ruin it in a hurry. Also, be sure the body and engine are well-grounded, especially if you're using an early-type alternator with a remote regulator mounted to the body. I've seen bad grounds cause full alternator output, even with a good regulator.
Jerry
