Not much English but try to explain.
my case.
48v-15ah (48x15=720) changes to 72v 10ah (72x10=720) so I stay the same autonomy but with more torque and speed.
your case
36v10ah (36x10=360) changes to 72v5ah (72x5=360) some autonomy more power and Speed.
(Google Tranlator) Sorry edit because I'm...