Honda Repair: alternator or something else ??, honda civic lx, 2001 honda civic lx

Question
So, this may sound stupid, but i did it to myself.
car - 2001 honda civic Lx 1.7
this saturday morning, i was trying to investigate a strange
rattling sound, coming from left side of engine while cold
and disappearing after 15min driving. I was'nt sure if it is
from ac or alt pulley or from timing belt area. So i took
apart alt belt, started the car. Car started fine, sound was
still coming from timing belt cover area, so i found out the
source of sound. NOW i put the belt back, tightened it and
started the car, car again started fine, ran for 2 seconds,
then RPMs dropped and i noticed that battery light was on ,
on dash board. I knew something wrong with with battery or
alternator. I took it to autozone, they checked battery said
it was bad. I got a new battery and came back. I replaced
the battery but light was still on. i checked new battery
voltage it was 12.6, i started the car, voltage went upto
14.4 or 14.5, then turned on headlights, rear defogger,
blower, tape one by one. voltage at bat terminals went down
to 12.8, 12.9. I asked someone to rev up the car to 2000
RPMs, voltage came back to 14.2.
then I disconnected the battery while car running, engine
went on running, no stopping or stalling.
Finally I checked under hood fuse #9 and under dash 10 & 4.
All were ok.
Car now starts and runs fine, with everything working but
battery light is on on dashboard. Any suggestion what might
be going on.

Answer
Mudassar, the alternator, battery and starter are directly linked together. You replaced the battery. Excellent decision. Batteries will last around 60 months. Depending on climate and driving conditions. Your battery has been failing you for some time now and your alternator has been working overtime to try and keep it up to operating voltage. Unfortunately the excessive strain on the alternator for whatever period of time might have reduced the life of the alternator. I would have the alternator diagnosed with a proper diagnostic load scan to see if it is up to proper specifications. An alternator, battery and starter specialist/shop should do this for you for free. Of course they might try to sell you something you do not need so view the results of the test yourself and make your own decision. 12.9V is not bad but, ideally 13.0 - 13.5V under load is where you ideally want to be. 14.4 - 14.5V non load is excellent.

As far as the battery light on the dash being on would be an indication that the battery is not charging or hooked up properly. Check all (-) wires and (+) connections carefully. You can also have AutoZone re-scan the vehicle and possibly remove the code? Or disconnect the (-) battery cable for 30 secs to a minute. This should reset things properly. You can also pull the hazard fuse under the hood for 30 secs to a minute too.