You want to let the battery drain until the device dies.
Then, plug the charge in and let the device charge until it is fully charged.
Once fully charged, then power it on.
I suggest repeating a round - leaving it used and uncharging until the device dies again, then fully charging again.
In the old days, this partly had to do with how batteries work. It was better to fully discharge then charge them. These days... not so much. Batteries are made differently and once calibrated, can be charged as little or as often as you need.
Definite improvement there.
But the Battery Sensing software still needs to be calibrated.
Below is a Lengthy Description - click the arrow:
Summary
Picture a jug of water. You can get pretty accurate in determining how much water is in the jug. You can give a percentage point within several decimal places. And... you can measure the volume in more than one way. You can weigh the jug. Or you can use measurement lines on the side of the jug.
Many people view a battery as a Jug of Electric. And many manufacturers want you to view it this way, as it gives the illusion of greater reliability.
A battery is not a jug. Of electricity or of water.
Electricity does not flow - like water does.
When water flows, the molecules, the particles, end up somewhere else. The move away from the source.
Diagrams and animations would lead us to think electricity flows like this. It doesn't. The molecules in the wire or in the battery stay put. They do not leave the source. You cannot weigh a battery to see how much electric is still in it.
When you add energy (in this case, the form of electricity) to an atom, the electron shell will ascend a valence (or however many valences are needed to accommodate the extra energy). Nature always balances her books, so in order to drop the electron down to the base energy level, it must pass that energy on. This can be in the form of heat or light (EM Radiation) or... if it is near enough to another similar atom - to pass that energy on to that atoms electron cloud. Which it passes to the next.
Picture a Bucket Brigade passing water, and you get a little bit better analogy than you would with a flowing river. The people stay put.
This is what makes it very difficult to measure the remaining charge in a battery.
Charge is measured with a series of algorithms that examine the voltage of the battery in relation to lithium ion chemistry, impedance and Coulomb count.
I said this on the forum before: When you know how it works, you are amazed that it works at all.
If you read the above summary, then you have an idea of how measurement works in order to determine the charge of a battery.
In order to achieve accuracy, you need to have Known Set Values, such as what chemical state the battery shows at very-near Zero Voltage. And what it looks like at max capacity.
Repeating this refines accuracy.
Calibrating allows the software to get these set values in order to reliably "predict" how much charge remains.