You need to remove the battery and get it fully charged. It could be a bad bettery, but you will not know until you try and put a proper charge on it. Those quick chargers are not good for the battery, they dump too much amperage in.
Your battery needs to go on a charger that puts out aprox 10 amps, and if its completly dead it will take hours for it to come up.
Once it is fully charged, let it sit overnight, then recheck your voltage and do a load test if the voltage still reads good,
after the load test let it sit for a few minutes and recheck your voltage to see if it recovered.
I would just buy myself a Optima and call it a day. They are one of the best batteries out there, I use the yellow top in all my vehicles.
The yellow top is a deep cycle battery that has plenty of cranking amps.