The small two pin connector goes to the controller. The red and black wires are supposed to connect to the battery output, but should have terminals or a plug instead of just wires stuffed in the hole, which obviously failed. That charger appears to be for a 36 volt battery, as the voltage is too low for a 48 volt. Are there any information stickers on the battery? The whole battery is sketchy, and if it was me, I would recycle it and purchase another battery. Is the original battery mount still on the bike? You can purchase another battery from Rad, but there may be delays, and Rad may not sell you one if the bike serial number is showing in their records as belonging to someone else. Other companies like Unit Pack Power make an original style battery that fits the original Rad mount, or you can replace the mount with an aftermarket one.