Intermittent charging problem

[nxsala]

Recently replaced the alternator on my 2005 explorer xlt. Sometimes the charging warning comes on when I start, its usually a cold start when this happens. I checked my voltmeter across the battery terminals when this happens and the voltage is lower than 12.5V which indicates the battery is not charging. Problem is if I drive for a few minutes the warning clears and the battery starts charging. This only happens every third or fourth start but its been happening for the last few months and now my battery is gone so I got a new one yesterday.

Any help on what could be the problem? Bad alternator or could there be a relay somewhere that is bad? I checked all connections and everything looks fine but I dont know where to test the alternator when the car is running.

 

[Number4]

Perform a voltage drop test on your cables.

http://www.explorerforum.com/forums/showthread.php?t=146784

My voltage at the battery was okay, but the light was coming on intermittently.
http://www.explorerforum.com/forums/showthread.php?t=434663

The fact that your battery died, you either have a cable issue or your replacement alternator was bad.