Pixiq

Here is an interesting idea to offset those AA battery purchases that I found on YouTube. Not sure about safety or if this really works. I just found it to be interesting!

Video 2 below, debunks this idea. My guess is that a 6-volt battery can be created with a number of battery types. Perhaps one in three might be built with AA size batteries but you may find that the 6 volt you purchase is made from other sizes such as D cells or something unrecognizable as shown in the second video. Those strange looking batteries are F cells. F cells are about 1.5 X the length of D cells.

It seems to me that these videos are showing two of a variety of possible sub-battery components that may be used to construct a 6-Volt battery.

In my research I found that 6 Volt batteries in the US normally contain F Cells which are larger in length to D cells.

"6 Volt

The 6 volt variety typically has spring terminals or screw terminals. Different types have different internal construction; the same package size may be made up with "D" size or "F" size cells, giving different capacity. A double size version (same size as two normal versions next to each other) exists for applications requiring more capacity." - Wikipedia

By this evidence, this hack seems not be a reliable source for a certain size or type of battery. It would appear that you take your chances in more ways than one.

It seems, hackers will do anything they think will save them money.

I would suggest you do some research before attempting to do this! 

Warning: If you should try this, do so at your own risk!

Video 1: