I have 6 lifepower4 batteries. They have been working fine but noticed one of them will only charge up to 73%when the rest of them are fully charged. I just now noticed that while my batteries are at about 45%, that one is at 12% and the alarm light on the battery is flashing. These batteries were all pretty close to the same percentage at one time, so why is this 1 suddenly lower than the rest? It is the second battery in the bank of six.