I have late 2012 MacBook Pro Retina. Put in a new iProPower (amazon) battery and it would not charge. Power report recognized the battery; said it was 48% charged; gave a capacity of 6700 mAh, but was not charginging. Per a thread I saw while back, remove the MegaSafe charger cable: then: (1) disconnected the battery, but did not remove it (it has adhesive, you know); (2) I held the power button down for 5 sec. , then reconnected the battery. attached the charging cable, and it CHARGED with great Power Report. I did not have to reset the SMC. This may not apply to all cases, but some might benefit if you know your battery is OK.