Could be one of the following. 1. Bad battery – swap the leads on your charger and see if the blinking disappears. If so, then probably a bad battery. 2. Bad charger – with the leads swapped to another battery, if the blinking appears, then you may have a bad charging bank 3. bad connection If you suspect that you have a bad charger, then call Cul M Rite / Pro Pak (if you have that type of charger). Good people to work with and will further help diagnose your problem. Good luck.