Did you measure the voltage across the terminals with the car running? I agree it's probably the battery, but before you buy a new one you should at least make sure that your charging system is working properly.

 

No, but that's a good suggestion. I'll do it tomorrow and see what I get. The car's going in for a new catalytic converter on Monday, so I'll ask them to check it out for me, just in case.

 

Battery tip: Clean the terminals and make sure they are tight!

A few steps to diagnosing batteries with a voltmeter (follow in order).

Step 1. With the engine running (jump start if necessary) and no lights on, the battery voltage should be close to 13 or 14 volts. If not you most likely have a charging issue (dirty connections, alternator, etc.)

Step 2. With the engine off and nothing turned on, the battery should be close to 12 volts. If not check to see if you need to add water (except in optima batteries). If the water level is ok, then you probably have a bad battery or dirty connections.

Step 3. With the engine off and the lights on, the battery should stay close to 12 volts for a couple of minutes. If the battery voltage quickly drops several volts then check to see if you need to add water (except in optima batteries). If the water level is ok, then you probably have a bad battery or dirty connections.

*****Disclaimer: This is not a comprehensive diagnostic procedure and may not always diagnose the problem correctly.****

 

You can close it with the drop down box at the bottom right hand side of the page. Or I can do it.

 

I was NEVER able to jump my optima yellow top on my RSX... It would die after 2-3 days of not driving it. I would have to take it to autozone to charge it for 4-6 hrs.... After 2 times of doing that, the battery tested bad and wouldn't charge again. I wanted a replacement for it, but NO autozone in the whole dallas metro had one... They only had ONE with the polarities reversed on the end of the battery.