Einhell PLUS Power X-Change Battery Twin Pack. The Einhell Power X-Change Li-ion Batteries are controlled by a micro-processor, which monitors its key parameters such as temperature, voltage and current strength. This provides effective protection against overheating and ensures the right balance for optimum operating conditions. The battery can be charged irrespective of its charge level. An automatic check establishes conditions on which the charging process depends. In normal conditions, for example, the high-speed charging process is started directly. In other conditions, e.g. extreme cold or exhaustive discharge, gentle charging is performed at reduced current strength. This charging method protects the battery and is essential for ensuring a long service life. The intelligent charge control system controls each battery cell individually, ensuring each cell is fully charged. This produces maximum supply of power. Overcharging is not possible, so even a charged battery can remain in the charger. The battery has a 3-stage LED indicator which indicates not only the battery charge, but also extreme temperature conditions. It also has a triple shell design for optimum protection against damage. Specifications:Battery Capacity: 4.0Ah. Battery Chemistry: Li-ion. Voltage: 18 Volt. Einhell Plus Power X-Change Battery Twin Pack 18V 2 X 4.0Ah Li-Ion in Red