There are a lot of 18-volt batteries on the market. Do not buy any battery for your Equalizer® tools except a DeWalt® 18V XR+ part number DW9096 or DC9096 XRP. It is the only battery that will run your tool correctly. Other batteries may actually run the tool backward and unscrew the drive mechanism. Some are underpowered and will destroy the switch. DeWalt® makes a battery they call a 18-volt Compact Battery Pack, part number DW9098 -- Do not use one of these. They are not strong enough to run your Equalizer® tool properly. Some Black & Decker batteries will fit -- They are all too weak so do not use them. Do not use Panasonic batteries. Use only DeWalt® 18V XR+ batteries.