Usually (maybe always), 48 V controllers have capacitors for 60V or 64V (can't remember) so are safe for 14s (52V) which charges to 58.8V. However, getting a battery that can interface with the Super 73's controller may not be easy (I don't know what their system looks like), and (probably) will increase top speed by a couple of mph, but not add that much range unless the batter has a higher capacity. If I were you, I'd just procure a second "73" battery (then, again, I'd get an ONYX CTY). Disclaimer: The ONYX is illegal to ride as a "bicycle.