Result of Pismo battery test. First, in System Preferences/Energy Saver, I set the HD to never sleep & the display to sleep after 15 minutes of idleness. Then I made a note of the time (0130) and emoved the power supply. I checked it a few times then went to sleep. I awoke at 0745 & checked the battery, it was 19% & the whole thing kept going for at least 40 minutes more.
So that was a battery life of around 6 hours on standby.
Fifteen minutes ago I started the process with another battery, this one at 70% of its original 4800 mAh capability.