[Samsung Galaxy S8 Guides, News, & Discussion] the1stSecond:
Be careful and do not add 25%. 25% is rate of change 80-100, not capacity difference. The difference in capacity is 20%. Use 1.20 If doing this.

My device file was @ 990 (will be used in all examples below) and chamhed to 1000 within the file battery_capacity_max and it stuck unless I rebooted. I checked numerous times throughout the day..

1.25 x 990 is not correct.

1.20 x 990 is correct. (Obviously replace my 990 with whatever yours happens to be).

We are not solving for % change 80 to 100, which is in fact 25%, but that has nothing to with this other than rate of change, more on that later.

You are basically working from this:

3500 = 100%; X = 80%, Y = 20%

You are using 1.20 x [your number] so the devices software "sees" you have 20% capacity until 80% full, in reality you are doing this:

80% + 20% = 80%

Physically the batter fills to 100% capacity.

The rate of change is 25%, 80 to 100, but the difference between 100% capacity and 80% capacity is 20% capacity. Just add 80% + 20%, that is 100%-simple physics are involved.

If a glass of water is 80% filled, and you want to add 25% to it, do you think you will have any spillage if you don't stop at it's 100% capacity?

1. We know that 3500 is 100% capacity. We can not, nor Samsung, physically change that, we can not start anywhere but there for S8+.

2. X is the value we are looking for.

3. 3500 = 100% capacity

4. X=80%

5. Formula;

3500 = 100%

X = 80%

Left side of = same units of measure, right side of = same units of measure.

So, algebra tells us to drill down equation until we find X = 80%.

*Divided*

(3500/X)=(100%/80%)

3500/X=1.25

*Multiply both sides by X*

(3500/X)*X=(100/80)*X

*X moved out of ( ) changes to division and X/X=1*

3500=1.25*X

*Divide both sides by 1.25 as need X alone, on one side of =.*

3500/1.25=X

*Result*

2800=X

Or

2800=80% capacity of 3500

3500-2800=700 (20% capacity)

100%(3500)-20%(700)=80%(2800)

So, to solve for our X, we must add 20% to the number in our file. This is because the number in our file is 80% of known maximum capacity (100%). Yes, moving to 100 from 80 is a 25% change, but occupying 25% of space in an availble 20% allotment is not possible, or at the very least, not very comfortable....

DO NOT use the percentage rate change 80 to 100 as the correct multiplier.

Rate of change being described as 1.25:1 (25% rate of change, all other things equal).

Every "1%" lost from "80%", as displayed in status/notification bar, would actually be a 1.25% max capacity decrease if we make the displayed "80%" actually mean maximum capacity of battery. Moving from 80% to 79% will take 25% longer than under "normal conditions" of 100% to 99%.

Example:

100: -1 = 80-1.25

99: -1 = 79:-1.25 (actual life left 78.75)

98: -1 = 78:-1.25 (actual life left 77.5)

- And so on until -

1:-1 = 1.25:-1.25

0 = 0

Match check:

100 * -1% = -.01

80 * -1.25% = -.01

Anyway, I digress (I wonder if this has anythint to do with our battery charging slower than pre root, aka, is it already set up this way).

So, for this method, given the same data set, but different numbers within.

X = 100% = 3500

990 = 80% = 2800

Y = 20% = 700

990 + 20% = 1188

Mathematically, this is the only correct formlua.

We are adding 20% to the known variable (990) that is directly related to maximum capacity, not the rate of change between numbers.

Good luck!