I have a 2005 Accord LX 2.4L w/ 101k miles and a few weeks ago, the battery light came on. The battery was changed last year. After checking everything, I concluded that it was a bad alternator, so I ordered an OEM reman alternator and replaced it. The light went away.
During the alternator replacement, I felt that the tensioner pulley was spinning too freely and making a little noise. So, just to be on safe side, I got a new OEM pulley from Honda dealer and replaced the pulley. I put 41lbft on the M14 pulley bolt based on a YouTube video. The alternator and pulley replacement were separated by 2-3 days during which I drove for 2-3 hours.
Fast forward a week from pulley replacement, my battery light is coming on intermittently while driving, stays on for 2-3 seconds and goes off. My observation so far is it happens when I brake but not every time I brake. I did basic continuity/voltage drop checks. At idle with full load, 130mV drop between battery positive and alternator positive and 30mV between battery negative and alternator housing. The 4 pin connector on the alternator is not damaged. Voltage at battery terminals with full load at idle is 14.05V, and 14.28V without any load.
The drive belt has at least 35k miles on it but does not have any cracks. Could the belt be slipping?