Just curious: I have 2 bikes and just bought a charger. I know some 12 volt systems can use 2 batteries and still be 12 volt. I'm wondering if I can pull the batteries out of the bikes, attach them + to + and - to -, and hook them to the same trickle charger/battery tender for the winter. The charger has a smart on/off feature, so I'm hoping I can just set it up and forget it until spring.