I went to replace the batteries on one of Bec’s toys the other day, and I checked the back of the toy where it said 2 x AA” Batteries and got the batteries and the screwdriver. When I opened it up, I found this:
which is a plastic case in the shape of 1 1/2 AA batteries that contains 3 x button cell batteries. I honestly can’t believe this is cheaper than sticking in 2 cheap batteries, but it must be, possibly because the button cells don’t leak for years.