Question about Rechargeable Battery Storage

For lithium ion it absolutely does matter according to everything I've read. Do not store with 100% charge. Some guys say that even charging it to 100% is not good (even if you use it immediately).

Edit: Here's some info.

https://batteryuniversity.com/learn/article/charging_lithium_ion_batteries

quote:

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Consumer and most industrial Li-ion chargers charge the battery fully. They do not offer adjustable end-of-charge voltages that would prolong the service life of Li-ion by lowering the end charge voltage and accepting a shorter runtime. Device manufacturers fear that such an option would complicate the charger. Exceptions are electric vehicles and satellites that avoid full charge to achieve long service life.

Simple Guidelines for Charging Lithium-based Batteries

- Lithium-ion does not need to be fully charged; a partial charge is better.
- Not all chargers apply a full topping charge and the battery may not be fully charged when the “ready” signal appears; a 100 percent charge on a fuel gauge may be a lie.
- Apply some charge to an empty battery before storing (40–50 percent SoC is ideal). (See BU-702: How to Store Batteries.)

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https://batteryuniversity.com/index.php/learn/article/how_to_store_batteries

quote:

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There is virtually no self-discharge below about 4.0V at 20°C (68°F); storing at 3.7V yields amazing longevity for most Li-ion systems. Finding the exact 40–50 percent SoC level to store Li-ion is not that important. At 40 percent charge, most Li-ion has an OCV of 3.82V/cell at room temperature. To get the correct reading after a charge or discharge, rest the battery for 90 minutes before taking the reading. If this is not practical, overshoot the discharge voltage by 50mV or go 50mV higher on charge. This means discharging to 3.77V/cell or charging to 3.87V/cell at a C-rate of 1C or less. The rubber band effect will settle the voltage at roughly 3.82V. Figure 1 shows the typical discharge voltage of a Li-ion battery.

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"SoC" means state of charge. So 40-50% charge is best. Fascinating stuff. I mean it would be better if you could charge it to 100% and store it with no self-discharge, but as long as you know how to handle them, you can make them last a long time. If you keep it charged below 80% all the time it will probably have a longer service life.