I think I killed my batteries. I have 6 12V 41Amp Yellow Top Optima batteries on my motorcycle and after only 2 seasons of riding none of them hold more then 12 volts and discharge below usable levels if they sit a few days. I have a Zivan NG1 charger that I thought was charging them correctly but now I'm not sure. I would plug in the charger after everyride and let it go. I assumed it shut off when it was done and sometimes I just left it plugged in overnight? Can anyone help me diagnose if the charger is working properly or if I did something to the batteries?