On Fri, 29 Aug 2014 15:53:08 +0100, Johny B Good
wrote:

I suppose it depends on how much value you place on the benefit of
having a functioning Mempac battery fitted into the controller. In my
case, it's not so critical for every day operation with the mains
supply proving, thus far, to be as reliable as it has been over the
past 30 years or so where I live.

My main hope in posting my query was that someone else in this group
may have already dealt with this issue in a remarkably economic way
and would jump at the excuse to disseminate their hard won knowledge.
:-) If you don't ask, you'll never find out so it's worth a punt
before wandering off into the wilderness of commercial reality.

Done similar; when I couldn't find the exact battery (or at an
exhorbitant price) I made an external pack and encased it in a similar
surface-mount unit to the controller. Looked fine, and not out of
place.