I have ordered a 36v 6.8ah battery to match the existing stored battery. I am awaiting arrival of that and a connector to either plug straight in or a waterproof connector to cut the original charger lead. Will incorporate an inline fuse to limit the voltage surge,if any. As long as both fully charged before using. Another rider has used on, switch on reserve battery and bike powers up. No use of system for 5 mins and it shuts down. Repower reserve battery to wake the system. I am looking at incorporating a voltage meter so that no damage done. It will fit into standard bottle holder. I am an electrician by trade so aware of dangers and damage potential. I will be checking every stage as I go with my testers