Johnny B Good wrote:

I might yet invest in another battery pack
for my basement UPS after all (a small 7AH one - I'm not made of money!).

I'm using four of the Powerline PL17-2 in a SU-2200, which at £80 for
the set isn't too bad, they've been in use for over two years and are at
89% capacity, I don't run the weekly self-test but it has run a couple
of times for power cuts.

Their NP7 equivalent is only a tenner ...

https://www.tayna.co.uk/PL7-12-Powerline-Mobility-Battery-P9076.html