We used a Lithium D cell in a prototype wireless product at a startup I worked at in 1989. The cells were pre-production samples. I forget the name of the company that was producing them now (I think it was a Japanese company - there were no logos on these batteries), but we were warned not to let them short out as they would go off like a 1/4 stick of dynamite. We were pretty careful with them, but we did have a unit come back from the field that had pretty much burned up, nothing but a charred circuit board left and most of the plastic enclosure melted away.