Your alternator should be producing 13.8 to 14.2 volts. On whatever gauge you have, it should be in that ballpark. The easy test is to take your little amp/volt tester that we all have in our toolbox, and do a simple output test at the battery. With the engine running, you should see 14 volts +/-.2 .Check it bofore you start it and see what increase you get.