Picture the scene, it’s Christmas morning, the kids are opening their presents and can’t wait to turn them on and play with them. Oh, they need batteries. No problem, you’re sure you’ve got some in that top kitchen drawer with the envelopes, tiny Ikea pencil, and a selection of elastic bands. Great news! You were right, you put them in the toy and they work. Just as you’re about to sit back and relax while your kids bathe in the glow of their new presents, you don’t even get the praise for  ...