Luckily I'm empty atm Geoff.
Wow Terry a fire !
I was sick of my old UPS which insisted I replace it's battery with their own proprietary battery or else it wouldn't work.
This one from Jaycar uses common SLA's (which BTW can be stored in any orientation)
The beauty of it is that they show you in the instructions how to wire up extra SLAs for a longer runtime period, so I'm thinking maybe a few in parallel will give me heaps of time to run my system.