Step 34: Turn AA batteries into C cells and D cells
An AA battery is the same height as a C cell or D cell.
Just wrap some cardboard around the AA battery so it's the right diameter. Here I use cardboard strips cut from milk cartons. I fasten them with tape or rubber bands.
New rechargeable AA batteries have plenty of power to run devices that used to require the bigger batteries.
I've seen commercial C and D cell batteries that are merely AA batteries with a plastic tube around them to bulk them up.
The green rechargeable on the right is a NIMH bulk cell removed from a laptop battery. It didn't have a nipple on the positive post. So I punched a disk from a penny and soldered it on the positive post.
Now it's the right height and works fine.