Self-discharge

Source: Wikipedia, the free encyclopedia.

Self-discharge is a phenomenon in

batteries in which internal chemical reactions reduce the stored charge of the battery without any connection between the electrodes or any external circuit.[1] Self-discharge decreases the shelf life of batteries and causes them to have less than a full charge when actually put to use.[1]

How fast self-discharge in a battery occurs is dependent on the type of battery, state of charge, charging current, ambient temperature and other factors.

Primary batteries are not designed for recharging between manufacturing and use, and thus to be practical they must have much lower self-discharge rates than older types of secondary cells. Later, secondary cells with similar very low self-discharge rates were developed, like low-self-discharge nickel–metal hydride cells
.

Self-discharge is a chemical reaction, just as closed-circuit discharge is, and tends to occur more quickly at higher temperatures. Storing batteries at lower temperatures thus reduces the rate of self-discharge and preserves the initial energy stored in the battery. Self-discharge is also thought to be reduced as a passivation layer develops on the electrodes over time.

Typical self-discharge by battery type

Battery chemistry Rechargeable Typical self-discharge or shelf life
Lithium metal No 10 years shelf life[3]
Alkaline No 5 years shelf life[3]
Zinc–carbon No 2–3 years shelf life[3]
Lithium-ion Yes 2–3% per month;[3] ca. 4% p.m.[4]
Lithium-polymer
 Yes ~5% per month
better source needed
]
Low self-discharge NiMH
 Yes As low as 0.25% per month[6]
Lead–acid
 Yes 4–6% per month[3]
Nickel–cadmium Yes 15–20% per month[3]
Conventional nickel–metal hydride (NiMH) Yes 30% per month[3]

References

  1. ^
    ISBN 978-0-444-52745-5
    .
  2. ISBN 9780444626103
    .
  3. ^ a b c d e f g Battery performance characteristics, MPower UK, 23 February 2007. Information on self-discharge characteristics of battery types
  4. ^ Umweltbundesamt: "BATTERIEN UND AKKUS" (3,65 MB PDF), October 2012; visited 2018-02-14
  5. ^ "Lithium Polymer Battery Technology" (PDF). Retrieved 14 March 2016.
  6. ^ Panasonic

Further reading

External links

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