Understanding of Lithium Battery Self-discharge

You may have experienced that when your car has been parked for a long time without being used, and when you start it again it can’t start.

You may find your energy storage battery was charged before, but after being placed for a long time, when you take it out for use, it has no power at all.

Why is this happening? Here, we have to understand one of the characteristics of lithium batteries: self-discharge.

What is the battery self-discharge?

Self-discharge refers to the phenomenon that the electrons inside the battery flow spontaneously without the action of the external current, resulting in a gradual decrease in battery power.

This is due to the nature of the electrolyte inside the lithium battery. Ions in the electrolyte can move freely between the two plates of the battery, causing current to flow inside the battery.

To be simple, the battery capacity will decrease while it’s storage without being used because of this self-discharge characteristic.

What decides the self-discharge rate of a battery?

The self-discharge rate depends on factors such as the quality of the battery, temperature, electrolyte concentration, and the state of charge of the battery.

Different types of batteries will have different self-discharge rates.

Normally, the rate of batteries is as below:

Lithium batteries: 1% ~ 3%.

Lead-acid batteries: 5% ~ 20%

Ni-MH batteries: 5% ~ 15%

The Storage environment of batteries will also affect the self-discharge rate.

If the battery is stored for a long time, or stored in a high-temperature, high-humidity environment, the self-discharge rate will increase.

Therefore, when using batteries, care should be taken not to use them for a long time, and to store them in a low temperature and dry environment.

The influence of the battery self-discharge?

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1- Affect battery lifespan

Self-discharge of the battery will cause the power of the battery to drop. If it is in a low-power state for a long time, it will have an adverse effect on the service life of the battery.