clock goes dim, not the battery?

Hey guys,

I have a 98 explorer sport and I noticed my clock going dim every once in awhile. Immediately, I went to advanced auto parts and had them check my battery. They said that even though my battery is starting to get low, my battery was not quite ready for replacement. According to them, there little handy tool would also tell them if it was possibly my alternator.

Now, Late last night and this morning i drove the explorer and didn't seem the radio dim at all. Was this just a freaky ford experience for me, or should i be worried about a greater problem? let me know what you guys think.


Btw, My headlights do not go dim, nor does the rest of my dash. I did notice at one point the radio clock dimmed when my turn signal was on. Thanks!