Page 137 - Battery Reference Book

Silver oxide-zinc primary batteries 5/3
5.1 Silver oxide-zinc primary PM Silvercel battery. This manually filled silver-zinc
batteries battery, which has a higher specific energy output than
alkaline manganese, carbon-zinc or mercury types
The weight and size of a silver-zinc battery or cell is of battery, provides rapid activation and an activated
less than half that of a lead-acid or nickel-cadmium stand time far longer than that of any other high-energy
type of similar capacity. The silver oxide-alkaline zinc primary. Additionally, it offers a limited recyclabil-
(Ag,O KOH Zn) primary battery is a major contribu- ity which allows performance testing before actual
tion to mniatiire power sources, and is well suited use. Silver-zinc batteries have surpassed the stringent
for hearing-aids, instruments, photoelectric exposure mechanical requirements of missile applications and
devices, electronic watches and as reference voltage proved their ruggedness and reliability in the field.
sources. The following advantages are offered by this battery
Silver oxide batteries provide a higher voltage than system over alternative systems: up to 75% higher
mercuric oxide batteries. They offer a flat voltage capacity, or higher capacity with optimum life, or
characteristic and have good low-temperature charac- higher voltages at peak pulses. By carefully choos-
teristics. Their impedance is low and uniform. The ing the critical application requirement that must be
silver oxide cell operates at 1.5 V (open circuit volt- met, whether it be capacity, life or voltage, and then
age 1.6 V) whiile mercury cells operate at about 1.35 optimizing these in relationship to each other, it is
or 1.4V. Two major suppliers, Union Carbide and possible to satisfy the single most stringent demand.
Mallory, supply silver-zinc button cells in capacity The characteristics of the Yardney PM cell are iden-
ranges between 35 and 210 mA b and 36 and 250 mA h tical to those of the Yardney HR and LR Silver-
respectively. Cylindrical and button cells are avail- cel rechargeable secondary battery system with the
able from vaious suppliers. The impedance of silver exception that cycle life and wet life are somewhat
oxide batteries for hearing-aid use is low and consis- limited.
tent. It does not rise appreciably until after the volt- Details of the types of silver-zinc batteries available
age of the battery has fallen below a useful operating from some suppliers are tabulated in Table 5.1.
level. Performance data for monovalent silver oxide
Silver oxide cells have excellent service mainten- (Ag,O)-zinc primary watch cells and divalent silver
ance; generally 90% after 1 year’s storage at 21”C, oxide (Ago)-zinc primary watch cells are given in
and for up to 2 years without serious detriment. Cells Table 5.2
will last up to 5 years in inactive sealed storage
conditions. 5.1.1 Remotely activated silver oxide-zinc
There are numerous applications in the aerospace batteries
field, particularly where a high energy density bat-
tery is required which can offer both fast activation Silver-zinc primary batteries can be remotely activ-
and a long wet-stand charged life. It was to meet this ated for single use within seconds or fractions of a
demand that Yardney Electric launched the primary second, even after long-term storage, by inserting the

Table 5.1 Equivalents in silver-zinc cells using the silver oxide system
Nominal Nominal Height Diameter Duracell IEC National Ray-o-Vac Ucar Varta
voltage capacity (mm) (mm) (Mallmy)
(VI h)

1.5 115 4.19 11.56 WSll SR43 WSll RW14. RW34 301 528
1.5 83 3.43 11.56 ws12 5 29
1.5 - 6.33 11.56 IOL14 SR44 WL14 RW22, RW42 357 541
1.5 85 3.48 11.56 IOL120 549
1.5 70 2.79 11.56 IOL122
1.5 75 5.33 7.75 IOL123 SR48 WS6 RW18, RW28 309 546
RW28, RW48 393
1.5 120 4.19 11.56 IOL124 SR43 WL11
1.5 38 3.58 7.75 IOL125 SR41 WSl/ RW24, RW44 386 548
WL1 RW47 384 527
392 547
1.5 :250 4.83 15.49 IOL129 RW15, RW25 355
RW35
1.5 :200 5.59 11.56 WS14 WS14 RW12. RW32 303 521
1.5 180 MS76H EPX71 7301
1.5 70 MS13H 7306
1.5 120 MS41H 7308