Charging at any time will have no effect on the battery. Built-in shock absorbing features protect the battery. Sixteen (16) firm holding contact terminals reduce the risk of power loss/fluctuation in high vibration work environments. S built-in Memory Chip communicates with the charger to maximize battery life using 3 Active Controls (Current, Voltage & Thermal).If you ever have an issue with any of the tools you own please see your local dealer. The item "2 NEW 18V GENUINE Makita Batteries BL1830 3.0 AH 18 Volt For Drill, Saw, Grinder" is in sale since Friday, September 6, 2013. This item is in the category "Home & Garden\Tools & Workshop Equipment\Power Tools\Batteries & Chargers". The seller is "we_are_tools" and is located in Myerstown, Pennsylvania. This item can be shipped to United States.