I was under the impression it kept it even until it was too low, then dropped the levels. That's how all my Fenix lights have been...
Drove me crazy with the new PD32(was only a very dim setting, changed the batteries and nothing happened... then I tested them with my DMM and saw they were all...
I know you can find cheap motorcycle hid kits that you would probably be able to retrofit, ddmtuning.com used to offer really good deals. As for the battery you can probably rig up something with RC batteries if you needed to upgrade and wanted a rechargeable... or even a holder for 18650's or...