Just did a run time test on my ARC LSHF-P with my new Ansmann 2200mAh NiMH AA rechargeables in the 2AA TSP tail pack. It gave 3 hours of constant bright light in SUN mode before dropping down to MOON mode and running for another 2 hours 20mins before I stopped the test. The FAQ says its got a auto cut-off to protect rechargeables but I didn't want to risk the new cells.