I have a 98 Civic DX Hatchback with 138,000 miles. The battery seemed to be losing power so first thing I figured was testing the battery, it is fine it's only a year old. Next I figured replacing the alternator. Had it tested it wasn't charging the battery any longer. Replaced the alternator. Problem is still here. When I drive the car it uses battery power and alternator doesn't recharge it. The electrical system seems to fluctuate up and down continously because the headlights go dim and bright over and over the whole time the car is running and as the battery loses charge it gets worse until it will eventually drain the battery totally. Any ideas? The computer unit? I have no idea.

Scott

 

check your battery terminals and see if they are corroded, that would cause it to be weak. and then check the tension on the alternator belt, too loose will not produce the maximum amps

 

battery terminals are clean and tight and tension on belt is tight...I'm at a loss on this one.