Torstein

Mine was glued, so I had to cut the glue to open it. But, To raise the voltage a little, one can replace one or two of the AA batteries and put inn ls14500 batteries that have 3.7 volt. 14.2 volt with one ls14500 or 16.4 volt with two ls14500.

White's Heavy Duty 2200mAh NiMH Battery, is it packed with rechargeable AA batteries?

Made a drawing to be 3D printed for my Whites TDI SL. I think it a good configuration for the battery pack is 4 X 18650 + 1 AA battery in series, so it can give about 16,3 volts.