On 18/10/2020 11:00, Dave Liquorice wrote:
That's another partial solution but unless regulary tested the
batteries get cooked by being on constant "trickle charge".

This is an oft-repeated fallacy. A half decent intelligent charger won't
do this. I have just tested an 8Ah lead-acid that's been on charge since
August 2014 with breaks and discharge only when we've had power cuts,
and it's fine. Comes out at 5Ah when discharged at 250mA which I think
is good enough.

Obviously cheap chargers are a different kettle of fish entirely. I
recently encountered a wall-wart style thing that had unconditional
no-load voltage of 16.3V. It had killed a 12V lead-acid.

Bill