26
Battery
Battery Construction and
Characteristics
0
20
40
60
80
100
Discharging capacity (%)
1.6
1.5
1.4
1.3
1.2
1.1
1.0
Batter
y v
oltage (V)
Charging: 0.1 C
×
16 h, at 25
°
C
At rest: 3 h
Discharging: 1 C (E.V-1.0 V)
0
°
C
40
°
C
25
°
C
Discharging
Unlike ordinary dry cell batteries, nickel hydro-
gen batteries exhibit uniform voltage character-
istics when ongoing discharging of constant
current is carried out, and the voltage then
drops sharply when there is no longer any ca-
pacity.
CAUTION:
Advise the customer that, if the remaining
capacity alarm of the battery has been trig-
gered, the battery should be charged imme-
diately, or should be replaced with a spare
battery.
NOTE:
•
At high temperatures, the discharging capac-
ity of nickel hydrogen batteries is the same as
that at normal temperatures, but at low tem-
peratures, the discharging capacity drops, be-
cause the voltage is lower.
•
The recommended low-temperature usage
range for batteries is –5°C or higher. If the
surface temperature of the battery is –5° or
lower, only about 50 to 70% of the power
obtainable at room temperature can be ob-
tained. As a result, if using the wheelchair at
below-freezing temperatures, the power as-
sist function may not function sufficiently, or
the travel distance may be shorter.
•
At –5°C or less, the capacity display gauge is
outside the guaranteed temperature range,
and the display changes. (See the section on
the remaining display gauge, described later.)
•
Advise the customer that in winter, or at cold
temperatures, the battery should be stored
indoors. Advise the customer that, if the bat-
tery has unavoidably become cold, it should
be left at room temperature until it has warmed
up, before being used.