Lowes safety light - Lithium power?
 

Has anyone here been successful powering the Lowes tail light with a lithium pack?
My head light uses a 7.2V lithium and I wanted to power the front and the rear with this pack.
The Lowes light takes 4 AA batteries, but I haven't been able to get it run with my external battery.
My multimeter shows that there is a common 6V across both pairs of AA's, but I think the pairs
also do something with each of the 3V rails.