There have been tremendous improvements in battery technology, along with enormous investments in R&D. I suspect improvements in certified aircraft are slowed greatly by the need for certification, but this is a homebuilt aircraft forum.Somebody should tell Pipistrel. Either there have been recent tremendous improvements in battery technology or the the folks at Pipistrel are ignorant. Their literature from a few years ago claims their users can expect 300-700 cycles in actual aircraft use (before battery capacity is reduced by over 25%) At that rate and at the battery replacement price they charged, it worked out to $25-$58 per flight hour. Taking the midpoint, that was more expensive than the engine reserve AND hourly fuel for a Rotax IC engine (that would also allow the plane to actually fly under power for more than 45 minutes).