Bought this light 3 weeks ago. Still have not run down the 18650 battery. Bought my father the TA20, which uses the same battery. The TK11 lights up the night. TA20 not so much. TA20 has 12 settings. One of which works for something like 720 hours. I am so happy I have he TK11, that I worry that I might be a bad son. Hopefully, Dad won't hate me for giving him the more sophisticated but weaker light.