Energizer PP355 - Manual (Page 16)

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ENERGIZER BATTERY MANUFACTURING
VERSION 1.2
3.4 ‐‐ Multi‐Battery Applications
In some situations, a higher voltage or an increased performance level is desired for a certain
application. Zinc Air batteries can be arranged in series or in parallel as needed. Devices that use more
than one Zinc Air Prismatic battery introduce additional design considerations. An air plenum and air
access is required for each battery, and these can be independent or shared. Additionally, stacked
batteries require space above the air hole side of each battery. If two batteries are stacked with the air
hole sides facing each other, then a single air plenum can be used.
3.5 ‐‐ Recommended Cutoff Voltage
The recommended end of life for Zinc Air batteries is at 0.9 volts where essentially all available capacity
has been used. Below 0.9 volts additional chemical reactions may take place in the battery which can
lead to increased potential for gassing and leakage. Energizer recommends that devices are designed to
prevent the battery from being discharged below 0.9 volts. This can be accomplished preferably by a
complete disconnect of the battery circuit or by using a low voltage battery warning.
3.6 ‐‐ Fuel Gauging
Zinc Air Prismatic batteries have a relatively flat discharge curve compared to existing Alkaline solutions,
with the discharge curve sloping more at increased discharge rates. This can be seen in Figure 4 and
Figure 6. Although the relatively flat discharge curve makes the Zinc Air system more challenging to fuel
gauge with conventional voltage‐only measurements, the flat voltage profile helps make device
performance consistent throughout the life of the battery. A more sophisticated algorithm
incorporating additional measurements that are tailored to the specific application may be necessary.
This is similar to what is required for Lithium Iron Disulfide and rechargeable Nickel Metal Hydride
batteries.