The actual answer to this is the same as right after it came off the charger, because within far less than 24 hours, we’ve used it and put it back on the charger.
I am doing a test “rest voltage” today. I’ve been going about 6 hours so far, and it seems to have settled for the most part at about a half volt down. I’ll try to remember to add a few more points over the next day or so.
This is a battery which is two years old, went through a dozen or so cycles in its first month as part of Pereichi’s electric bicycle project, and has been used for rather light duty since. All measurements made with the same voltmeter - another one I have shows about 0.03V higher.
If you don’t already have one, pick up a Battery Beak and check the internal resistance (at the bottom of the display), if your batteries have an unusually high resistance it might be time to replace them. Our batteries generally have an internal resistance of around 0.017ohms-0.024ohms, and get a floating charge between 13.8v-14.2v right off the charger (I actually even saw one as high as 15v once, but that might have just been a fluke).
Also keep in mind that SLA batteries loose roughly 10% of their maximum storage capacity every 6 months when stored at room temperature (even more if they’re stored without a full charge). As a general rule, we try to replace our batteries every 1-2 years (though some older batteries can be kept for demos, practice bots, and as “pit batteries”).
The picture looks like the one I have, which is not what the current Power Patrol batteries look like; I had to search five or six before I found one with markings that look like mine. I suspect the picture is out of date. (That doesn’t mean I trust Amazon’s text 100%.)