One problem related to battery has been reported for the 1998 Jaguar XJ8. The most recently reported issues are listed below.
Battery exploded, filled trunk with smoke, blew electrical covers off of fuse and relay blocks which are located too close to the battery under the floor of the trunk. . Exploded when turned ignition key to start car--very violent--if trunk had been open, acid would have covered anyone nearby. Better shielding of the battery needs to be undertaken.