http://www.modelaircraft.org/mag/Jan2011/onthefly3.htm

This is from Maynard Hill, famous for the trans-atlantic flight :

http://www.modelaircraft.org/mag/mhill/hillindex.htm

technical details:
http://www.barnardmicrosystems.com/L4E_atlantic_crossing_II.htm

the link had made learn me two things in new:
1:use of toluene
2:it had its own generator.

I had a misconception that generators, if added to replace batteries may add extra weight to the plane, and affect its performance. Secondly, definitely it affects the engine's performance as well.