re: No one can make batteries that cost less than ...
"No one can make batteries that cost less than the mains electricity they can charge and discharge in their lifetime"
Nissan Leaf battery 24kWh@0.25/kwH (total incl line charges) = $6 * 365 = 2190 *10years = $21,900
Replacement cost for Nissan Leaf battery (no exchange) $5000.
Nope looks like we are already well past economic!
In fact: Nissan Leaf 2012, 11000km = $19,995
I think I'll just leave it parked outside as a nice battery box, and sell the motor and tyres as spares on ebay