Self-discharge

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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. Self-discharge decreases the shelf life of batteries and causes them to initially have less than a full charge when actually put to use.

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, which aren't designed for recharging between manufacturing and use, use battery chemistry with much lower self-discharge rates than rechargeable batteries, since they must have an economically practical shelf life.

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[edit]

Battery chemistry Rechargeable Typical self-discharge or shelf life
Lithium metal No 10 years shelf life[1]
Alkaline No 5 years shelf life[1]
[[Zinc–carbon baLow self-discharge NiMH Yes 2% to 3% per month
Lead-acid Yes 4% to 6% per month[1]
Nickel cadmium Yes 15% to 20% per month[1]
nickel metal hydride (NiMH) Yes 30% per month[1]

References[edit]

  1. ^ a b c d e Battery performance characteristics, MPower UK, 23 February 2007. Information on self-discharge characteristics of battery types

Further reading[edit]

  • Wu and White, "Self-Discharge Model of a Nickel-Hydrogen Cell." Journal of the Electrochemical Society, 147 (3) 901-909 (2000)

External links[edit]