I took a 2 month old battery to advanced auto to get charged. after an hour they told me it was bad. I took the same battery to the repair shop i bought it from to get a replacement, instead, they told me they could charge it and did without a problem. Now the battery is 5 months old and I let it drain (my fault will explain that problem later) by mistake and had to take it to advanced auto to get charged. again they tell me after an hour that the battery is "bad" I wonder if I take it again to the repair shop i bought it from if they will charge it like last time. what is it that causes one shop to be able to charge a battery and another shop to call it "bad"? is it me? the battery? or shop attendants that are faulty?

I think to get an better answer, you need to find out what "bad" means from advanced auto. If it is just low output, then Advanced Auto is going to of course going to try and sell you another battery, where as the repair shop wants to keep you as a customer and just went ahead and charged it regardless of the battery's health.