-long time participater, many self inflicted casualty's...
;-0 Just kidding...
"to recharge a battery is about 13.8v right?"
hmmmmm, lets see here, basically yes you can charge any battery at a-boot 14 volts. In fact, most 'flooded' lead-acid battery's have a full state of charge at 12.95v. I have some VRLA glass mat battery's (the reactor type), and they wont tollerate over 14volts period.
"power of the wind cubed everytime the speed doubles....how could a VAWT also acomplish this?"
You know you could actually use that as a generalized question for its own topic.
JW