Energizer PP355 - Manual (Page 13)

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ENERGIZER BATTERY MANUFACTURING
VERSION 1.2
Figure 11: Overview of Different Air Management Techniques
high
low
continuous intermittent
none or small
degree of air
management
needed, since cell
capacity is quickly
used
(1‐3 months)
high degree of air management needed,
cell has high air access but is expected to
be in service with long periods of “off”
time (>3 months)
Duty Cycle
Di
sc
h
ar
ge
Rate
throttling needed to
maximize service
time (>3 months)
3.2 ‐‐ Elements of Air Management
Two elements of a successful in‐device air management system are a means for allowing controlled air
access to the battery and an air plenum for even air distribution. An air plenum is an air gap, or volume,
which has access to all of the air holes on the battery. The air plenum allows for more even air
distribution over the battery air holes, and it provides a reserve of air immediately available to the
battery to handle peak power needs. Controlling air access to the battery is accomplished by creating an
access path to the sealed volume of air within a device. The air access path is designed to allow a
desired amount of air to flow to the sealed volume of air, which includes the plenum, either
continuously or intermittently. A sealed volume of air can be created by sealing an entire device, a
portion of the device including the battery compartment, or just a plenum above the air hole side of the
battery. The power requirements of the device determine the rate at which air is required to flow to the
battery.
Figure 12 illustrates a simple, cost effective air management solution designed into a device. The
compartment door contains an o‐ring which seals against the air hole side of the battery when the door
is closed. The air plenum volume is defined by the compartment door and the sides of the o‐ring. A
slide switch is located in the compartment door to create an air access point. The slide switch acts as a
valve which seals the compartment when in the closed position and allows air to flow to the battery
when in the open position. The slide switch could be mechanically manipulated by the user or
electronically controlled by the device.