I got an Acebeam H40 and a couple Orbtronic 1100 mAh 14500 cells to try out. On turbo 1050 lumens, the battery did reach full brightness but dimmed down to maybe 500 lumens during the minute on turbo before it switched to high (battery not rated for 4 amps). Runtime on turbo (1 minute)+ 350 lumen high was 57 minutes. Runtime on regular 230 lumen high was 2 hours and one minute. Runtime on 15 lumen low was 25 hours 58 minutes. These are runtimes until low warning flash comes on (flashes every 10 seconds). Overall, a good headlight for those who want a lighter light with replaceable batteries with a turbo setting as bright as an 18650 light.