MAHLE Smartbike Systems X35 SP1 External Ebike Battery/Range Extender - Battery Holder Cable Retention StrapsMAHLE Smartbike Systems X35 SP1 External Ebike Battery Range Extender Battery Holder Cable and Retention Straps. The Mahle SP1 Range extender battery provides 36V 250W of additional power bringing the total capacity to 450W. The Range extender includes a holder that mounts to the water bottle bosses on the frame. It charges the main battery while riding and offers a parallel power supply to the motor when the power draw exceeds 2A. 36V 250W Panasonic