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Nickel-cadmium secondary batteries 51/19

Table 51.22 Full range of Varta Mempac memory protection cells
Nominal capacity (mA h)
20 60 100 140 170 250
1.2 V nominal batter;\. voltage
Battery type 1/20 DK 1/60 DK MOO DKO 1/140 DK 1/170 DK 1/250 DK
Drawing number DB 901/1 DB 892/1 DB 826/1 DB 862/1 DB 863/1 DB 864/!
Nominal voltage (V) 1.2 1.2 1.2 1.2 1.2 I .2
Final voltage (V) 1 .o 1 .o 1 .o 1 .O 1 .o 1 .o
End-of-charge on charge voltage (V) 1.45 1.45 1.45 I .45 1.45 I .45
Trickle charge rate (mA) &IO% at 1.45V/cell 0.2 0.6 1 .o 1.4 1.7 2.5
DC internal resistance (fully charged) (ma) 2200 1300 500 450 375 300
Battery length (mm) 5.35-0.3 6.2-0.4 6.0-0.25 6.1-0.6 6.7-0.6 8.8-0.6
Maximum battery diameter (mm) 11.5 15.5 Oval 25.1 26.0 26.0
6.0 V nominal battery
Battery type 5/20 DK 5/60 DK WOO DKO 5/140 DK 5/170 DK 5/250 DK
Drawing number DB 901/5 DB 892/5 DB 826/5 DB 862/5 DB 863/5 DB 864/5
Nominal voltage (V) 6.0 6.0 6.0 6.0 6.0 6.0
Final voltage (V, 5.0 5.0 5.0 5.0 5.0 5.0
End-of-charge on charge voltage (V) 7.25 7.25 7.25 7.25 7.25 7.25
Trickle charge rate (mA) 3~10% at 1.45V/cell 0.2 0.6 1 .o 1.4 1.7 2.5
DC internal resistance (fully charged) (ma) 11000 6500 2500 2250 1875 1500
Battery length (mm) 28.8-2.0 31.5-2.0 30.4-1.25 30.9-3.0 33.9-3.0 44.4 - 3.0
Maximum battery diameter (mm) 12.0 15.8 oval 26.0 26.0 26.0

Table 51 23 Varta Mempac S series of 100 mA h capacity cells
for CMOS-RAM memory protection
Order No. Nominal Width Length Height Weight
boltage (mm) (mm) without (g)
(V pins
I
I
I
I
I
(mm) 52.31 I 600 I 1200 I 1800 I 2400 , 3000
0
Discharge time, r (h) at 20 pA
53010701012 1.2 17-0.4 42.4 10.5 9
53010702012 2.4 17-0.4 42.4 16.0 15 Figure51.8 Discharge of a Varta Mempac 100mAh memory
53010703012 3.6 22.2-0.4 40.3 16.0 21 protection cell to supply a load current of 20pA (Courtesy of
53010704012 4.8 30.0-0.3 40.0 16.0 26 Varta)
battery's negative temperature coefficient is taken into
account, better than 2V are still available, 2V being
the minimum voltage many volatile memories need in
order to meet their performing specification.
To allow for variations in minimum operating volt-
ages, the number of cells may be varied to suit
il.01 I 1 I I I I I I I I the memory's requirements. Care should be taken to
.- 0 1 2 3 4 5 6 7 8 9 10 ensure that sufficient charging voltage is available to
5:
D Time (h) fully charge the battery.
Figure 51.9 shows the effect of discharge rate on
Figure 51.7 Discharge of a Varta Mempac 100mAh memory discharge duration for a range of Mempac cells. The
protection cell at the 10 h rate, O.IC,OPI (Courtesy of Varta)
capacity required for memory support may be calcu-
lated by multiplying the discharge time by the dis-
at +20"C. When discharged at rates less than O.lCloA, charge rate, adding sufficient capacity to allow for
the voltage plateau will be extended. Mempac batteries self-discharge losses.
may be discharged at lower rates than O.lCloA. When choosing a battery for memory support:
Figure 5 1.8 shows the voltage a memory may expect
to see when using a three-cell 100 DKO Mempac to 1. Allow for self-discharge when deciding the capacity
supply a load current of 20 PA. It can be seen from this required.
curve that even at extremes of temperature, when the 2. When selecting the number of cells, ensure that: