Strong expansion and internal heating causes the ice to explode.
Duracell D battery in ice.
This battery was directly connected to a 24 Volts 5 kVA transformer. No variac was used.
Interesting to see the current build up in the cold battery.
Have a look at Kurt's channel too.
http://www.youtube.com/user/Kurtreidable
I created this video with the YouTube Video Editor (http://www.youtube.com/editor)