I do change my battery every year according to the manufacturers specs
because I've had a number of experiences with other digital devices
being ruined when you let the batteries get real low and then replace
them. I've lost a couple of watches and a few calculators that way. In
all of these cases, the batteries were very old but still functioning.
Everything worked fine till I put in new batteries. I've decided it's
cheaper to replace the batteries more often.
The first time I changed my sram battery, I forgot to leave the card in
the calculator and leave the calculator turned on. The battery was only
out for a few seconds. The card was dead and had to be re-formatted. That
was with an HP 512k card. I later did the same thing with a 2mb Ace card
to test it, but the same thing happened. As long as the card is in the
computer and the computer is turned on, everything is ok.
There probably are differences in technology that allow some cards to last
with now power while others cant.
Barry