1995 Mazda Millenia owners have been puzzled as the batteries in these vehicles frequently go dead even when the alternator (Bosch p/n AL4220X and AL4219X) is working properly.  When these vehicles were produced, some of them had the trunk light switch installed incorrectly!  The clearance between terminals A and B on the switch may have been set too close together, so that, when the trunk is closed, these two terminals are still making contact.  

To correct this condition, Mazda suggests that you loosen (but do not remove) the screw that secures the trunk light switch.  Then, place a screwdriver in the trunk lid latch to "close" the latch.  With the lid latch "closed", the body of the trunk switch should be gradually turned until the trunk light goes off.  When the light goes off, the screw previously loosened should be tightened securely.