Could be talking out my <img src="/forums/images/graemlins/butwiggle.gif" alt="" /> here but there are several tests you can do. First, if you are seeing a voltage drop when you turn you accesscories on, watch the guage. The alternator should jump up to compensate for the draw you are asking of the battery. That's a simple test.

Next, you could do a current draw test to see what happens when you ask the charging system to do its job. Not sure what equip you have at your ready or how much such a test would cost but it's worth looking into. 'Course my new motto is "think outa the box and spend as little money initially to diag. before you move on to the BIG stuff).

A Hydrometer test on your Batt. wouldn't hurt either.

HTH...

dawn...