Body Battery

I'd expect those values to me something like

max-current

and 

min-current

I think they rather mean: currentValue: 25, increaseSinceMidnightL +2, decreaseSinceMidnight: -23

And yes, you need to use the last value from the history (in the above case it should be 25). It's updated every 5 minutes in FR245 as far as I could tell.

Hi,

How can I obtain increase and decrease values?

you'll need to read the history since midnight and try to calculate it yourself.

Are you sure it's "since midnight" and not for the length of the history?

From here, it appears to be how many times it's gone up vs down and can account for a longer period of time.
https://support.garmin.com/en-US/?faq=VOFJAsiXut9K19k1qEn5W5

Where do you see any hint on that? I see "at the end of the day". But more importantly I simply see that each midnight it starts again. Basically those 2 numbers seem to be some "counters" that the algorithm that plots the graph splits out. It probably counts how many times the next pixel (on the x axis) went up/down compared to the previous.

Things like this.  No where does it say things reset at midnight, just that the goal is to have the numbers about the same at the end of the day.

"

My Body Battery Appears to Be Stuck at 5%

If you have a new device, or if you recently reset or restored your device to its factory default settings, it may require 5-7 days to learn or re-learn your body. "

What Do Charged and Drained Mean?

For compatible products, charged and drained are displayed in Garmin Connect, showing how many points of Body Battery was recharged or recovered vs. how many were spent or used up. Ideally, there should be a similar level of each at the end of the day, indicating a balance of activity and recovery. Too much of one without the other is not recommended.

5-7 days is for "teaching" the body-battery algo. It has nothing to do with the charged/rained numbers IMHO.

The only hint is in the last paragraph: "at the end of the day".

But unfortunately Garmin is known to have not very precise documentation. However I can tell you that I do see the charged/drained numbers reset at midnight. Have a look tonight and you'll see (here it's just part midnight, so I could even verify it today) 

Hi, JIM. Do you know any icon set published by garmin with a body battery icon? Thanks