 Later electric systems used more-efficient brushless DC motors and higher-capacity nickel metal hydride (NiMh) batteries, yielding considerably improved flight times.The recent development of cobalt-content lithium polymer batteries (LiPoly or LiPo) now permits electric flight-times to approach, and in many cases surpass that of glow-engines – however, the increasing popularity of the much more rugged and durable, cobalt-free lithium iron phosphate-celled batteries is increasingly attracting attention away from LiPo packs.There is also solar powered flight, which is becoming practical for R/C hobbyists.