"Roger Druce" writes:

I would like to be able to charge up a 12 volt (nominal) gell cell battery
and then plug it into a piece of equipment to check its total AmpHour
capacity during discharge at some constant rate current (say the "10 hour"
rate or the "20 hour" rate). All this towards assessing whether the battery
has proven useful capacity and life left in it, or has it reached its
discard date?

The equipment would show the delivered amp-hours up to the point at which
the voltage has fallen to a nominated end voltage.

At the research lab I work at, we use a power resistor (for the load) and a
strip chart recorder (Vout/time).
Steve