[Samsung Galaxy S8 Guides, News, & Discussion] partcyborg:
So I didn't get the numbers you specifically asked, but a few things I did get and some caveats:

1) I have a standard size and I don't remember my original number exactly (it's buried in an old rom backup right now) but it was in the 800s. From my recollection the s8+ was close enough to 1000 for it to matter a lot less.

2) I proved this was adding charge by doing the following:

a) plug into my 2017 MacBook charger (it's usb-c) which is only relevant as to it being way overkill, and has high quality cables, so when i was stock it always fast charges and I've even had rare occurrence of fast charging rooted.

b) charge all the way to as full as possible at 80%. Unplug and plug back in a few times and wait a bit (sometimes healthd or whatever seems to get stuck close to it's artificial cutoff point), essentially making absolutely certain you aren't charging anymore and are at maximum and basically drawing from battery (or effectively or whatever)

c) make the change in /sys to put it at 1000. Make the change now in efs too (but I don't think that was relevant)

d) unplug and immediately plug back in once or twice to kick over healthd (as I recall this was necessary to make it notice the change, but it's been a while at this point.

At this point, the following happened. You'll have to take my word on it at least for now but I hope you realize it would be pointless and pathetic to make this up, and if absolutely necessary I'll reset and do it again on video or whatever you want.

1) battery percentage drops something like 7% (I don't remember the exact number) as reflected on status bar and in kernel loglines from healthd

2) phone resumes charging again. Status is confirmed charging by the red charge light (I've done no fancy root config to adjust that light), and healthd log lines also reflect that the device is charging again vs when it was stopped at 80%. I don't remember which is which but basically at the 80% case healthd repots one status as "Charging" and a different one (it's like State or something) says "Draining". This appears to be a reflection of the arbitrary limiting going (and made me look furiously at healthd for hours and hours before learning that abl controls everything either directly or indirectly so the game is over until there is a bl unlock).

3) phone continues to charge (reflecting above state) over the next like ~20m or so (I don't really remember the exact time but it was around there) with the metric growing back towards 80% again.

4) The phone hits 80% and stops like before. At this point max batt capacity is 1k in all places (could have been minor noise I dunno).

5) reboot the device while plugged in and at the new 80% level. This is important to "commit" the new value to efs as it will set the value as it stands at whenever the operation happens in the reboot process.

Basically, if you reboot with the value <1k whatever that value is is what winds up in efs. The device appears to use this value as some kind of high water mark and my best guess is it lets the battery kernel systems interact more efficiently with the hardware by not always spinning waiting for full to the brim. I have no evidence of this though it's completely a best effort guess.

The evidence my device was powered to a full charge as given by the combo rom, that I triple checked that it was really full by giving it plenty of time, restarted the charge process by very quick unplug+plug, with patient waiting in between, and the the simple act of changing the value in /sys is sufficient to not only drop the overall charge percent the appropriate specific effective amount when comparing the ratios between the two sets of numbers, that the device reported both at the UI layer (the red charge led) AND more convincingly, both mutated from current rooted "full" behavior to the exact "charging" behavior normally exhibited, AND this number also increased at a best guess regular rate of charge increase until hitting 80% again.

I state that in my professional-software-engineer-and-not-quite-amateur-android-contributor opinion I strongly believe that the above evidence is irrefutable proof that some amount of charge level is increased. The specific. Umbers would likely really upset some people, but I'm confident enough in my assessment that I'll do it if you just can't believe me and think I made all this up (lol).

Maby months later, my efs still has the 1k value and I see no reason outside proving this to everyone for good to undo it. Even 5% is worth 30m of effort one time.