At 21:59 23 February 2017, wrote:
Tesla is CLAIMING to be building batteries costing under 200
eur/kWh...


Here in EASA land I think there are substantial cost
implications to certifying "new(er)" batteries in an existing
certified FES sailplane (for Ultralights it's different). As current
FES performance looks pretty adequate why would the
manufacturers do it; it's not like there has been any radical
evolution in battery performance.
Dave Walsh