" FWIW, I wonder what percentage of initial capacity was left in good old phone company batteries after 10-20 years on switching station standby duty? I'll bet a lot or all - assuming their electrolyte levels were properly maintained."
Calcium calcium is designed for standby. A 20% level of discharge 80% remaining, not to be left 20% discharged in excess of 200 hours.
These are strict limitations. The 20 percent rule meant battery banks were (usually) huge.
But quiescent standby loss is negligible. Therefore less kWh needed to maintain 100% charge in standby mode.
Evolution of loss of electrolyte is minimal. About 2% that of 5% antimony batteries. Less external corrosion.
Batteries. gentlemen, choose your compromise.
Calcium calcium is horrible for deep cycle use.