1: Fasten the Dual Battery Bracket to the downtube of the bike.
2: Remove the battery from the downtube and remove the wire shield shown bellow.
3: Using three fasteners, remove the charging pins.
4: Remove the plastic side plate.
5: Push the charging pins out of the frame.
6: Insert the dual battery's wiring into the frame and connect the dual battery connector. The 2 inputs from the batteries go into the input terminals of connector and the output terminal goes to the controller as shown below.
7: Turn on the bike to confirm that it is working and put everything back together. The loosening of charging pin will allow you to position the connector inside the controller box easily.