August 2000
NICKEL METAL HYDRIDE HANDBOOK, PAGE
9
The hydrogen-absorbing alloy negative electrode
successfully reduces the gaseous oxygen given off
from the positive electrode during overcharge by
sufficiently increasing the capacity of the negative
electrode which is the same method employed by Ni-
Cd batteries. By keeping the battery’s internal press-
ure constant in this manner, it is possible to seal the
battery.
NICKEL METAL HYDRIDE BATTERIES - CONTINUED

Features

••
••
•Similarity with Ni-Cd batteries
These batteries have similar discharge characteris-
tics to those of Ni-Cd batteries.
••
••
•Double the energy density of conventional
batteries
Nickel-metal hydride batteries have approximately
double the capacity compared with Panasonic’s
standard Ni-Cd batteries.
••
••
•Cycle life equivalent to 500 charge and
discharge cycles
Like Ni-Cd batteries, nickel-metal hydride batteries
can be repeatedly charged and discharged for about
500 cycles. (example: IEC charge and discharge
conditions)
••
••
•Rapid charge in approx. 1 hour
Nickel-metal hydride batteries can be rapidly
charged in about an hour using a specially designed
charger.
••
••
•Excellent discharge characteristics
Since the internal resistance of nickel-metal hydride
batteries is low, continuous high-rate discharge up to
3CmA is possible, similar to Ni-Cd batteries.
P-120AS
Ni-Cd
HHR160A
Ni-MH
Discharge Capacity (mAh)
Voltage (V)
1.6
1.4
1.2
1.0
0.80 200 400 600 800 1000 1200 1400 1600 1800 2000
1.8
HHR200A
Ni-MH
Size : KR17/43
Charge : 1CmA X 1.2h
Discharge : 0.2CmA
Temperature: 20˚C
HHR200A
Ni-MH
P-120AS
Ni-Cd
HHR160A
Ni-MH
Discharge Current (A)
Capacity (mAh)
1800
1600
0 1 2 3 4 5
Size : HR17/43
Charge: 1CmA X 1.2h
2000
1400
1200
1000
800
600
400
Temp.: 20˚C
2200
H
+
H
+
H
+
H
+
H
H
H
H
Charge
Discharge
MH
x
M
O
Ni
OH
(Negative Electrode
Hydrogen-absorbing Alloy) (Positive Electrode
Nickel Hydroxide)
OOH
Ni
Schematic Discharge of Ni-MH Battery