Just an update (for sharing purposes and for future reference as well to those who might experience this problem), I went to several auto-electrical shops and they said:
- battery needs replacement
- broken alternator


I went to buy the easiest part, the battery. Voila! It still doesn't work. Though the most sensible explanation was from a battery shop. He said that the battery is already busted, and the alternator is not charging correctly. From the voltmeter, the reading was 14V with A/C on, and it drops down to 12V with HL and A/C turned on. That's a problem as per the mechanic. It should stay at 14V even with all electronics turned on. His explanation was the alternator is not charging the battery/supplying enough current anymore. Nag-aagawan daw, kaya pati yung dashboard lights, nag-d-dim with HL turned on. And the reason why the engine conked out after an hour drive in traffic is that the A/C and HL are getting current from the battery that is not charging. So eventually, it was drained. Now I have a new battery, it would take a longer time to get drained, but the problem is still there: the alternator.

I also asked what needs to be done to the alternator, the auto-electrician told me that it needs replacement. It can be repaired/rewinded, but not the carbon repair. If there's a problem with the carbon, the battery dashboard light indicator will always turn on. But that's not the case for me. It was never on. Now I asked them to repair the alternator, but they prefer the surplus replacement and quoted me Php 4.5K.

Any comments fellow tsikoteers on the surplus alternator? Is it better than a repaired alternator? Is 4.5K a fair amount of parts and labor cost? Can you suggest an auto-electrical shop that you know or trust that repairs/replaces alternators? Thanks again in advance guys!