Page 142 - Battery Reference Book

5/8 Silver batteries
Table 5.5 Characteristics of Yardney Silcad silver-cadmium batteries

Chemical reaction Ag + Cd(OH)2 = AgO + Cd + HzO
discharged charged
Energy output Theoretical 310 Wag; 48-75 W Wkg; 90-160 Wb/dm3
Open-circuit voltage 1.40 * 0.04V (70-100% charged)
1.16 & 0.04V (30-70% charged)
Nominal voltage under load 1.1v
Plateau voltage regulations &5% at a fixed load and temperature limits within f5"C
Recommended discharge 0.60 V
cut-off voltage
Recommended charge cut-off 1.65 V (indicated by sharp rise in cell voltage at 1.55- 1.60 Vkell during charge)
voltage
Cycle life Dependent on model and conditions of use; typical number of complete
charge/discharge cycles obtainable:
Depth of discharge(%) Approx. cycles
95-75 200-300
75-50 300-600
50-25 over 600
Wet life Up to 3 years when manufacturer's recommended charge and discharge rates are
used and operating and storage temperatures do not exceed 37°C
Dry storage life Up to 5 years
Gassing on discharge or stand Very slight
Operational temperature f73 to -21°C; down to -53T with heaters; for optimum cell performance, from 10
range to 51°C
Storage temperature range Wet, +37 to -47°C; dry +73to - 64°C
Operating attitude In any position although, for optimum service, upright is recommended
Internal resistance Very low; varies with cell model, temperature and rate of discharge
Resistance to mechanical stress Excellent, extremely rugged, leakproof, spillproof. Construction similar to design of
Yardney Silvercel batteries which meet requirements of Spec. MIL-E-5272A, and
are currently used in missiles, rockets, torpedoes, etc. Can be packaged to meet the
most severe requirements
Charging time Can be fully recharged within 10-20 h, depending on requirements and type of cell
(in some cases rapid charging possible)
Charge retention Up to 85% of nominal capacity after 3 months' charged stand at room temperature

adopted with an input of 1.65 f 0.02 V. With constant- design concepts to those of their nickel-hydrogen sys-
potential charging the current is limited to one-fifth of tem. The silver-hydrogen couple is believed to be
nominal capacity charging to the trickle charge rate. capable of achieving energy densities in the range
90- 110 W h/kg with maximum cell operating pres-
sure of 2.75kN/m2 and an energy volume relation-
5.4 Silver-hydrogen secondary ship of between 61 and 79Wh depending on cell
batteries design. The silver-hydrogen system is believed to be
capable of 600 deep discharge cycles (80-90% depth
Eagle Picher have also explored the possibilities of of discharge).
developing a silver-hydrogen battery using similar