Defined "so I charged it"
Does this mean you took it on the freeway for a 20 mile round trip, or that you used a plug in charging source of at least 6 amps, and left it applied for at least 12 hours?
Any time a battery rests at less than 80% charged, the sulfates on the plates are hardening. The lower the battery state of charge is, and the longer it rests there, The harder they get and it becomes less and less likely that charging voltages will ever redissolve them back into the electrolyte, no matter how high they go or how long they are held there. Sulfation = capacity loss/ performance loss/ CCA loss, and hardened sulfation is not easily dissolved, ever, even if one really wants to believe the marketing material provided by modern charging sources which claim to defy physics, and then fellate the user afterwards too.
I have had several severely capacity compromised batteries which would still pass a load test. I personally do not trust any load test that does not ask the battery to produce half the CCA rating for 30 seconds and still hold over 7.5 volts.
The battery could be toast, even if only a year old. Easiest way to kill a battery is to let is discharge slowly, and then sit in an undercharged state for an extended period of time. When this is done the Age of the battery means very little. It can be killed nearly as easily as an older battery, an no simply recharging it does not make it right again. The 30 gallon gas tank has shrunk to 5 gallons, never to expand again.
And the alternaotr is not some physics defying instant battery charger. A battery drained to 80% state of charge cannot be recharged to 100% in less than 3.5 hours, and those 3.5 hours would be when the battery is held it ideal absorption voltages.
Ideal absorption voltages are NEVER held by any vehicles voltage regulator, so in reality those 3.5 hours required to go from 80% to 100% are doubled or tripled at 13.7v, and it is debateable whether 150 hours at 13.7v can ever fully recharge a less than healthy battery to 100%.
