Electrical Help Please

The battery had been on a Battery Tender for 2 weeks and was fully charged when I drove it 3 miles to the parts store. Is that fully charged enough? Or do I have to take it out of the car and drive it to the parts store?

With the meter showing 14.25v while the car is running, I don't think it was hurting the battery to drive it there. Unless the battery just isn't taking the charge like it's supposed to????

What do you think?
It needs to be load tested. A battery with a shorted cell can still read 12.8 volts, but drops to near zero when load is applied.
Sounds weird, but I've seen it myself more than once. Some will have enough juice for lights, but a starter load....nada