before TT's nifty pcb,  the other solutions was to use any standard 1/2 aa Lithium battery.

3v - 3.6v they are all 3.6v

desolder those batts,  get some holders

http://www.mouser.com/ProductDetail/Eagle-Plastic-Devices/12BH1-2AA-2P-GR/?qs=sGAEpiMZZMuSFBMFeRq2EX4WxdDvwgXR



solder those down, and pop in your batteries,

for example i like to buy my 1/2 AA's from this guy he is cheap!

http://www.ebay.com/itm/Lot-of-50x-ER14250M-3-6V-1-2-AA-Lithium-Battery-with-LED-light-/181193036942?hash=item2a2ff2548e:m:mE40pIt_MzFyNVbpOyDWi-A



if you want the included PCB cool... if not,  then tell him and he will clip out and test each battery for you.

I usully buy at-least 100 at a time and he usually includes about 20 more just as a nice gesture.

but keep in mind these batteries are not really fresh... but they are NOS (new old stock).

I'v had really good luck with them,  been buying them from him for almost 2 years now.

he has like 25 thousand left.