most of my flashlights and radios are c cell but i do have some d cell units , was sitting a round wondering how to put cs in ds , i found some 1 in pvc conduit cut it off at 4 5/8 in. plus 2.75 in quarters and it worked. i tried washers to no avale. i put 2 of these in the radio. placed a piece of tape on it for a tab to make it ez er to remove. goining to look for some 1 in aluminam round bar in stead of the quarters . will be looking to do aaa in aa when done with this.
Get crank radios and flashlights...no more problems.
If you really are looking to get ideal survival equipment, crank gear is the best. So long as you can turn the handle you have power, no worry about batteries going dead. And for flashlights, I suggest LED lights, they are super bright, and use MUCH less battery power.
It is cool that you figured out how to use different sized batteries though.
__________________
If the Founding Fathers were alive today, they'd probably rather be dead.