Panasonic HHR200A - Manual (Page 4)

NICKEL METAL HYDRIDE HANDBOOK, PAGE 10 AUGUST 2005
•
Discharge temperature characteristics at 1It
discharge
•
Discharge temperature characteristics
3) Storage characteristics
These characteristics include self-discharge
characteristics and restoration characteristics after
long-term storage. When batteries are left standing,
their capacity generally drops due to self-discharge,
but this is restored by charge.
Charge Capacity (%) (Nominal Capacity Ratio)
V
oltage (V)
1.6
1.4
1.2
1.0
0.8
0 20 40 60 80 100 120 140 160
Charge : 1CmA x 1.2h
Temperature : 20˚C
Model
: HHR200A
1.8
0.6
2.0
20˚C
-10˚C
0˚C
120
100
80
60
40
20
0
-20 -10 0 10 20 30 40 50
Discharge Temperature (˚C)
Capacity Ratio (
%
)
3It
1It
Charge : 1CmA x 1.2h
Temperature: 20˚C
Discharge : Cut-off Voltage 1.0V
Model
: HHR200A
Temp.: 20˚C
Ni-MH (HHR200A)
Temp.: 45˚C
Ni-Cd (P-120AS)
Storage Period (weeks)
Capacity Ratio (%)
Charge : 1CmA x 1.2h
Discharge : 1CmA to 1.0V/cell
100
90
80
70
60
50
40
30
0 1 2 3 4
NICKEL METAL HYDRIDE BATTERIES - CONTINUED
•
Charge temperature characteristics at various
charge rates
2) Discharge characteristics
The discharge characteristics of nickel-metal hydride
batteries are affected by current, temperature, etc.,
and the discharge voltage characteristics are flat at
1.2V, which is almost the same as for Ni-Cd
batteries. The discharge voltage and discharge
efficiency decrease in proportion as the current rises
or the temperature drops. Compared with Ni-Cd
batteries, nickel-metal hydride batteries have inferior
high-rate discharge characteristics, making them
less suitable for use in applications requiring high-
current discharge. As with Ni-Cd batteries, repeated
charge and discharge of these batteries under high
discharge cut-off voltage conditions (more than 1.1V
per cell) causes a drop in the discharge voltage
(which is sometimes accompanied by a
simultaneous drop in capacity). The discharge
characteristics can be restored by charge and
discharge to a discharge end voltage of down to 1.0V
per cell.
•
Discharge characteristics
-10 0 10 20 30 40 50 60 70
Charge Temperature (˚C)
Capacity Ratio (%)
0.1It x 12h
0.33It x 4h
1It x 1.2h
Charge
0.33It
0.1It
1It
Discharge : 0.2It to 1.0V
Temperature: 20˚C
Model
: HHR200A
110
100
90
80
70
60
50
40
0.2It 1It 3It
Discharge Capacity (%) (Nominal Capacity Ratio)
V
oltage (V)
0 20 40 60 80 100 120
Charge : 1CmA x 1.2h
Temperature: 20˚C
Model
: HHR200A
2.0
1.8
1.6
1.4
1.2
1.0
0.8
0.6