... possess higher discharge voltage. This series are designed specially for cordless power tools, which possess higher discharge voltage, and can be charged ... -discharging, over-charging, high temperature, and so on.3. Green power, ST battery is free of Pb, Cd, Hg, Cr6+, PBB ... and PBDE, they are environmental friendly chemical power source.4. Long cycle life, more than 500 charge/discharge ...