1990 accord ex not charging
 

I have a 1990 honda accord ex and the battery light comes on after the car warms up at which time the engine starts to stall. I put it in netural and rev the gas to keep it going. Had the battery checked out and I took the alternator in and had it checked at 2 diffrent shops and that was not the problem. They said it tested out fine. I cleaned off electrical contact points to it before replacing and purchased a chiltons manual to read thru and still could not find any trouble shooting info for it to isolate the problem. Not sure what else to do. Any help would be great! Thanks for any info.

If you have a multimeter, check the battery voltage when the engine is running fast idle[warming up]. Should be around 14VDC
And see if the voltage drops below 13VDC when the engine RPM goes down to 700 [normal idle].
You might just need to replace the brush pak, or it could be a bad regulator.
When the alt is spinning at a higher speed; like when they test it there is enough output, but at slower speed not enough voltage.
To get to the brush pak you'll need to unhook the battery and then alt connections. Grab your 8mm & 10m and remove the Battery terminal insulator of the Alt then take the back cover off the alt.
2 phillips screws hold the brushes in. Use a good phillips to remove them because they are torqued in TIGHT.

Thanks for that great information Hondadude! Worked like a charm. The regulator in the alternator was bad . I did the voltage check and viola! Started at 14.64 and dropped to 12 at idle speed. Was able to get one at a wrecking yard for $40 and problem solved! Thanks again!