The Advanced Charging Battery is an upgrade of the Charging RE Battery added by IndustrialCraft 2. It acts much like an Advanced RE-Battery, although it can store more energy. Secondly, having one in your inventory will automatically charge any other (LV-MV) EU-powered tools or batteries in your inventory, similar to an Advanced Batpack. This is particularly usefully when compared to the Advanced Batpack, as it frees an armor slot for a Jetpack or something more protective.
An Advanced Batpack cannot charge an Advanced Charging Battery. Likewise, an Advanced Charging Battery cannot charge a Advanced Batpack.
The Advanced Charging Battery originally was a part of Aroma1997's Portable Recharger mod. However, it was annexed into IndustrialCraft when Aroma joined the IndustrialCraft 2 Dev Team.