I have a 2002 Civic. It acts like the battery is run down. I took off the battery and alternator and had them checked. They both checked out ok.
The battery runs down when the lights are on, and it acts like it is not charging properly. Thanks for any help.

 

The definitive test is to put the car all together, then measure the battery voltage (put the probes on the lead posts that are part of the battery, not on the terminals that are part of the car) with the engine running but everything else off. It should be more than 13.5 volts. Then turn the lights on and measure again. The voltage might drop a little but it should recover when you rev the engine to normal driving rpm of 2000 or so. If you have only 12.x volts with the engine running, the charging system is not working.

 

If anything at all give your battery terminals a good cleaning
How to Clean Car Battery Terminals | Cleaning Guides

 

Thanks

 

Thanks