Now, solder 2 wires to both contacts. Be sure the wires are long enough to reach the bottom part of the battery where you will solder them to the 1/4th inch female jack.
Drill a hole in the bottom of the battery to fit the 1/4th inch jack.
Insert the 1/4th inch jack then solder the two wires to each lead. Make note of the polarity (+ / - ).
I used hot glue to fasten it in.
Put the contacts back into the tip of the battery and re-assemble your battery.