Wow...a short circuit, even when a switch is closed. What are the odds?
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This indeed points to the internal chemistry of the new batteries, their high capacity charge, size, and design. When these batteries internally short, they are of such high amperage that it takes a long time for them to go dead and until that happens the battery and everything around it is glowing red hot and combusting.
The way these batteries can go critical makes one appreciate the self-limiting nature of gasoline combustion — i.e. the fact that its ability to burn is limited by the availability of oxygen. There is no such limit on the chemical fire that happens when a battery decides to burn.