Battery Handbook

Page|12

ENERGIZERBATTERYMANUFACTURING
VERSION1.2
Section3:ApplicationandDesignConsiderations


Excessive exposure to air can have an adverse affect on Zinc Air battery operation, primarily due to
carbondioxidereactingwiththeelectrolyteintheairelectrode.Thebatterycanalsoabsorbwateror
dryoutdependingon ambientconditions.Balanci ngtheairrequirementofthebatteryduringdischarge
versus
theneedtominimizeexposureduringrestiscalledairmanagement.Airmanagementmightbe
assimpleasremovingthetabfromthebatteryandinsertingitintoadevice,oritmightincludeasystem
to open and control air access to the battery as needed.Air management is
application specific, and
mostdeviceswillrequiresomedegreeofairmanagementtooptimizebatteryperformance.

3.1‐‐AirManagement

Thereareseveraltypesofairmanagement.Thesimplestmethodofairmanagementisremovingthe
tabandputtingthebatteryinthedevice.This ishowminiaturezinc aircellsareused inhearingaids
since the tot a l battery life is typically expected to be 6‐8 weeks.As
the device usage becomes more
intermittent,othermethodsofairmanagementareneededtodeliveroptimalbatteryperformance.

Throttlingisatechniquetopermanentlyrestrictairaccesstoonlywhat is neededbythebatteryin a
specific application.Throttling is most appropriate in devices that require a small portion
of the
maximum current that a battery can sustain.For example, a device might require 10 mA of current
comparedtothemaximumof100mAthataPP355cansustain.Thistechniqueworksbestfordevices
thathavealowaveragedrainratewithlittleincreas edpowerneeds.Byrestricting
theairaccesstothe
battery,theperformancelifecanbeextended.

As device use becomes more intermittent and as device power demands increase, valved (open and
shut)airmanagementbecomesmoreappropriate.Valvedsystemsareeithermechanicalorelectronic.
Eachsystemrequiresasealedbatteryorbatterycompartment,into
whichairisintroducedbythevalve
when the device needs power.A seal can be accomplished with common materials such as o‐rings,
gaskets,over‐moldedortwo‐partinjectionmoldedmaterials,orothermethods.Amechanicalsolution
might be an ON / OFF slideswitchwhichacts as
asimple air valve.Otherdevicespecificmechanical
actionscouldalsobeusedtoopenandclosetheairaccess.Examplesincludechanging devicesettings,
movingapieceora partofthe deviceduringuse,pressing abutton,turningadial, ormanipulatinga
threaded component.An electronic valve would
 act in a similar fashion, except that the device
electronicswouldopen theairaccessautomatically.Avalvecouldbeopenedasa function ofdevice
state(on=open,off=closed),oritmightbeafunctionoftheinstantaneouspowerneeds ofthedevice.
Inavalved
airmanageme ntsolution,alowlevelofairaccessmightstillbeneededtobeabletoprovide
thequiescent,orbackground,powerrequiredtoactivatetheON/OFFvalve.Figure11showsgenerally
whereeachoftheseairmanagementtechniquesisappropriate.