I like my Ay-Up lights but they are like so totally 5 years ago with their handlebar battery mount that needs a 100mm stem to be securely set up.

Has anyone got an elegant work around?

also interested, other than top tube mountings and stretched cables I’ve not really solved this yet.

use the extension cable they provide in the pack, for putting the head mounted batter in a pocket, and use that on the bar mount, and frame mount the battery?

I just strap the battery under the handlebar.

I use these quite a lot.

Ideal for small batteries:
http://www.dx.com/p/flashlight-universal-bracket-mount-holder-with-velcro-123733#.U_RX4PldWhU
90 degree version: http://www.miniinthebox.com/multifunction-bicycle-flashlight-mounting-bracket_p269435.html?pos=ultimately_buy_2

Have you tried the headtube?

Do other manufacturers have this problem? What do they do?

I can still get the small battery on a 55mm haven.