Step 3:

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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.