On Sun, 18 Oct 2020 04:01:46 -0700 (PDT),
wrote:

That's another partial solution but unless regulary tested the
batteries get cooked by being on constant "trickle charge".

There are self-testing ones available, eg
https://www.safelincs.co.uk/self-tes...ency-lighting/

Hum, not sure if that hastens the demise of the batteries or not.
B-)
What really annoys me is the use of "non-standard" battery packs. The
one I have that has failed takes some weird cell size, currently
solved with AA NiMH rechargeables and sticky tape...

But if mum is getting periodic visits, even quarterly, an ordinary one
can be switched off for an hour while the smoke detector is also
checked, etc.

Provided you remember to switch it back "on"... I like
systems/procedures that work by default rather than requireing any
action to be taken. Like the "self test" of battery motion sensor
lights.

--
Cheers
Dave.