Check the listing for details. Dual Battery Connection Adapter Switcher For Increase Battery Capacity E-bike US. Color: Black, Condition: New. Listed at 46.58 USD. The Dual batteries connected in parallel for additional capacity and range, and the switcher can manage the two batteries on your bike. It will detect the voltage of the two batteries in real time. When one battery is exhausted during riding, it will automatically switch from one battery to the other, again for you Powered by the electric bicycle, or support two batteries to simultaneously supply power to your electric bicycle intelligently and balancedly. Note: 1. Do not confuse the positive and negative connectors on the dual battery switch. Make sure that the power of both batteries is turned off before connecting. 2. Both batteries must have the same voltage 3. Suitable for maximum 30A or maximum 40A controller（Optional） Water resistant Applicable voltage：20V～72V Compact Size and Weight: 30A version：6*4.5*1.8 cm 40A version：7*4.5*1.8 cm Precautions: 1. If you need to use battery packs of different voltages, please confirm whether the controller supports it first. If it does not support multiple voltages, please purchase with caution. 2. This version does not include the charging function, but the regenerative controller can be recharged with a small current. Please confirm whether the battery protection system is the same as the charging and discharging version. WZZT#453-30A/40A