If folks are concerned about battery leakage, then why don't you just place the
battery inside a plastic box mounted remotely inside the cabinet (or even outside of it)
and wire it over to the circuit card? Then you can use SRAM with no write cycle limit,
without any risk of the battery leaking onto the circuit card or into the backplane.
--
Mark J. Blair, NF6X <nf6x at nf6x.net>
http://www.nf6x.net/