I have a DBS V2 that I got about 3 1/2 years ago. It is listed as DBS V2 w/3SM Cree XR-E module R2. I'm under the impression the 18500 extension tube will fit and allow me to use (3) CR123 batteries. But it stated the extension will only increase the run time. What would I need to get more light (lumens). Thanks.