why did my battries explode?

[Edd]

hi guys,

yes another battery gone down . i use a x-15 computerized charger and nimh much more 4800 mah 7.2v saddlepack batteries and like usual i charged it up today and then i hear a big bang, i go up the plastic container has a whole in it (fire proof) and the cap of one of my cells has fallen off or exploded off, i hear a humming noise in the battery.

my settings for charging is usually 5.0 amps and has been for the past 2 months however i thought i saw on the charger "8.62v" and i thought that was quite strange, so is that my problem?

sorry it sounds abrupt.


Edd