swede..... dude this is weird.....I got off work early today...and on the way home I picked up the exact same thing! and I was about to post about it . how freaky. great minds think alike I guess, I was just sittin down to figure out how to wire it up.... and you did it for me....crazy you are the man! soo you just spliced in between the switch and the 4 batt holder? just connected both negative together and positive together? I see a velcro strap there, where do you plan to mount the single cell? Man this is awesome timing.... for me I guess