How come my rechargeable battery self discharges so fast?

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SUMMARY

The discussion centers on the rapid self-discharge of a Nickel-Metal Hydride (NiMH) battery, specifically a 1300mAh AA cell, used in a piezoelectric energy harvesting project. Users noted that the battery voltage dropped significantly after removal from the charger, with self-discharge rates of 5-20% on the first day stabilizing at 0.5-4% per day at room temperature. The consensus is that the battery may not be fully charged, as the voltage of 1.2V does not indicate a complete charge, and the charging process is inefficient due to the low power output from the piezoelectric source. Recommendations include verifying the charging setup and considering the self-discharge characteristics of the battery.

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  • Understanding of Nickel-Metal Hydride (NiMH) battery chemistry
  • Familiarity with piezoelectric energy harvesting techniques
  • Knowledge of battery charging methods and efficiency
  • Ability to interpret charge/discharge curves for batteries
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  • Research NiMH battery charging techniques and best practices
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Engineers, researchers, and hobbyists involved in energy harvesting projects, battery technology enthusiasts, and anyone troubleshooting NiMH battery performance issues.

  • #31
When brand new, the cell has been self-discharging on the shelf for as long as it has been since it was charged at the factory. And, they may not have charged it to 100%. 1.27 volts is just what it happened to be at when you measured it. It has no meaning.

You need to fully charge it with a NiMH charger if you want to characterize it.
 
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  • #32
NascentOxygen said:
You are placing too much reliance on that voltage. It's more of a guide for a typical cell. The best way to estimate a cell's state of charge is knowledge of the charge you have put into it, and it seems you are delivering minimal charge from your novel source.

meBigGuy said:
When brand new, the cell has been self-discharging on the shelf for as long as it has been since it was charged at the factory. And, they may not have charged it to 100%. 1.27 volts is just what it happened to be at when you measured it. It has no meaning.

You need to fully charge it with a NiMH charger if you want to characterize it.

Thank you all for sharing. i think i need to find other source to verify. Since the source that i found is unsustainable.
 

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