Electronics > Projects, Designs, and Technical Stuff
New Alkaline Battery Leakage Testing
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magic:
By the way, it's a very different story with NiMH.

I have seen a few NiMH cells which leaked simply from lying unused for many years. One pair was pulled out of a cordless mouse, so it has never seen a fast discharges in its entire life, another I'm not even sure if it had ever been used at all.
EEVblog:

--- Quote from: graybeard on March 28, 2020, 07:10:40 am ---This paper on a US DOE web site describes in detail the chemical mechanism of battery leakage: Understanding the Dynamics of Primary Zn-Mn02 Alkaline Battery Gassing with Operando Visualization and Pressure Cells -- "It is shown that steep concentration gradients emerge during the cell discharge through a redox electrolyte mechanism, leading to the formation of high surface area Zn deposits that experience rapid corrosion when the cell rests to its open circuit voltage. Such corrosion is paired with the release of hydrogen and high cell pressure" —eventually leading to cell rupture" --  to me the paper suggests that fast high current discharge followed an open circuit may be best way to get leakage.  It also has some interesting electron microscope photos.

--- End quote ---

Thanks. I might give them a final 2A burst or something, they are currently on a 24hr 100mA discharge, as per this video:
Electro Detective:
Not sure if mentioned before, but what about the metal to metal differences between the battery and device terminals ?

Scenario:

air tight battery enclosure,

flat batteries,

metal to different metal thermocoupling effect ..or whatever it's called  :-//

resulting in internal expanding gasses in the battery with nowhere to go   

sealings compromised (kaput/knackered)

SPLAT n SPEW  :o

= C virus bankrupted Fluke or Brymen owners not happy campers  >:( :rant:

graybeard:
This is figure 6 from Understanding the Dynamics of Primary Zn-Mn02 Alkaline Battery Gassing with Operando Visualization and Pressure Cells

It shows both the recovery of voltage and the build-up of internal pressure when the battery is open-circuited from a hard discharge.



Atmospheric pressure is 14.7 psi, so 0 psig=14.7psi absolute.  So the normal hydrogen partial pressure is approximately 3 atmospheres.   So the peak partial pressure shown of 193 psig is 13.1 atmospheres.

For comparison, for submersion in water pressure increases one atmosphere for every 33 feet (10m).   Thus the peak partial pressure of H inside the battery equivalent to the water pressure at a depth of 400 feet (131m).   Based on the graph the pressure was still increasing at the end of the measurement so there is no reason to think it does increase to a higher value than shown. --> No wonder they leak!
Conrad Hoffman:
IMO, running down and leaving with a low load is the worst. I used to have an answering machine with a terrible design- when the batteries got low it would light an LED to let you know! :scared: The thing was the worst battery leakage device I've ever seen.
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