Alternator(??)/electrical problem. Help needed please.

Hi folks. I'll try to be as short as possible, but as detailed too.

Have a 96 Tercel DX (AT). Purchased new in 96 and THANKFULLY, no major problems to report. 'Till now. Last November, my original alternator went. At that time, I was 1000% sure it was the alternator. Replaced, and all was well until recently. NOW,...the battery won't stay charged (suspected faulty alternator). Purchased new alternator w/out even having a load test done, as previously/originally, the alternator was the culprit. Well,...replaced the "old" alternator w/ the new one, AND,...same results. Battery won't charge/hold a charge and (obviously) I know this alternator is good.

I checked the fuses, and all seem to be in perfect working order. I'm not overly "mechanically inclined" (obviously,...why I'm here @ AF.com). Hoping some of you fine members could help me resolve this lingering problem so that I can be back on the road. Thanks in advance!!

P.S. Belts are all fine too!

How old is your battery? I had the same problem a while back. Thought maybe the battery was dead, so I put it on the charger. After several hours, it showed it was fully charged. Worked for a day or two and then was dead again. Found out the battery had a bad cell. Although it showed as fully charged and good to go, that bad cell kept it from holding the charge. Or course I had the same problem with my motorcycle with a brand new battery too. Both showed good on the cheapo testers at the parts store. It wasn't until it was connected to a better tester at the dealer that it showed the bad cell. Hopefully your problems is as simple as that.