[shorod]

The first thing to check is the condition of the battery cables and their connection. Make sure the cables are clean and tight. Also make sure the cable connector ends are molded on the the cables and not the temporary type that clamp over the exposed copper cable and clamp the cable with a couple of bolts. These are prone to allowing the copper to corrode and cause bad connections.

Assuming your cables and connections are good, it sounds like you have a weak battery. If you have a multimeter you can test the condition of the battery and alternator. With the engine off and the car having been sitting for 15 minutes or more, the battery should hold at least 11.8 volts DC (battery). When trying to start the car the voltage should not drop below 9.5 volts DC (battery or starter load). Once started the battery voltage should be at least 13.8 volts DC (alternator).

If you find the battery is bad, take it back to where you bought it, preferably with the receipt in hand and have them test it. If it tests weak or borderline, have them replace it under warranty. Some places offer an 18-month free exchange, but at a minimum it should be pro-rated so you won't be paying the full price for a replacement battery.

-Rod