Hey Jake,

The most likely things would be an old, dying battery or a faulty alternator regulator or diode board. But first, how about a little more info, such as:

Was the battery recently inadvertently discharged? If so, what were the circumstances?

You say the alternator was replaced recently. Why? Was the regulator replaced at the same time?

How many miles since the replacement? Was this a new, used or remanufactured unit?

Who did the work, an indie, a dealer, or ?

Did they thoroughly check the charging system after installing it? What were the results?

Did they offer any warranty?

How many miles on the car?

Has the battery ever been replaced? Batteries often have a sticker that shows the month and year the battery was put in service. What's the date on yours? What brand and model is the battery in the car?

Do any dash warning lights come on when you turn on the headlights?

Any evidence of auxillary belt slippage such as squealing, or a shiny, slick surface on flat side of belt, or excessive belt deflection?

For quick, cheap check-up take the car to your local Sears and have them do a load test on the battery and also test the charging system. Many stores will do this for free or a minimal charge. They may also provide you with a printout. But don't buy anyting on their say so just yet. These aren't the most comprehensive tests, but sometimes they can point out a weak area.

Post your results and go from there.

Gary