This article provides a tutorial on daily care techniques for lithium batteries. Most misconceptions about lithium battery use arise from misunderstandings of related terms, so it's necessary to explain them specifically.
1. Memory effect
This is a common phenomenon with nickel-metal hydride (NiMH) rechargeable batteries. Specifically, if the battery is used without being fully charged, its capacity will drop significantly, and it won't fully charge even when you try to. Therefore, the important way to maintain NiMH batteries is to only start charging them after they are completely drained, and to only use them after they are fully charged. The memory effect of commonly used lithium-ion batteries is negligible.
2. Fully charge and fully discharge.
This applies to lithium batteries.
Complete discharge refers to the process of draining the power of an electronic device, such as a mobile phone, by adjusting it to the lowest power level until the phone automatically shuts down.
A full charge refers to the process of connecting a fully discharged smart device, such as a mobile phone, to a charger until the phone displays a "fully charged" message.
3. Over-discharge
This also applies to lithium batteries. Even after a complete discharge, a small amount of charge will remain inside a lithium battery, but this charge is crucial for the battery's activity and lifespan.
Over-discharge: After a complete discharge, if other methods are used to continue using the battery, such as forcibly turning the phone back on or connecting the battery to a small light bulb to consume the remaining power, this is called over-discharge.
It will cause irreversible damage to lithium batteries.
4. Protection chip
Lithium batteries have extremely strict requirements on the current and voltage applied during charging and discharging. To protect the battery from damage due to abnormal external electrical environments, a chip is installed inside the battery to manage its operating state. This chip also records and calibrates the battery capacity. Even counterfeit mobile phone batteries nowadays don't skimp on this crucial protection chip; otherwise, they wouldn't last long at all.
5. Overcharge and over-discharge protection circuit
Smart electrical devices have built-in chips and circuits that comprehensively manage battery operation.
For example, mobile phones have such circuits, with roughly the following functions:
1. During charging, provide the battery with the most suitable voltage and current. Stop charging at the appropriate time.
2. When not charging, check the remaining battery power regularly and turn off the phone at the appropriate time to prevent over-discharge.
3. When powering on, check if the battery has been fully discharged. If it has been fully discharged, prompt the user to charge it, and then power off the device.
Fourth, avoid abnormal battery or charging cable power. If an abnormality is detected, disconnect the circuit to protect the phone.
6. Overcharging:
This refers to lithium batteries.
Under normal circumstances, the charging current of a lithium battery will be cut off by the upstream circuit when it reaches a certain voltage (that is, when it is fully charged). However, due to the different voltage and current parameters of the overcharge and over-discharge protection circuits built into some devices (such as mobile phone battery chargers), the charging may not stop even when the battery is fully charged.
Overcharging can also damage battery performance.
7. How to activate
If a lithium battery is left unused for an extended period (more than three months), the electrode material will become passivated, leading to a decline in battery performance. This can be addressed by performing three full charge and full discharge cycles to remove the passivation and allow the battery to reach its maximum performance.
