Subaru 2009 IMPREZA, Service Manual

Page: 417 / 3619

SC(H4SO)-23
Battery
STARTING/CHARGING SYSTEMS
2) Measuring the specific gravity of the electrolyte
in the battery will disclose the state of charge of the
battery. The relation between specific gravity and
state of charge is as shown in the figure.
D: MEASUREMENT
WARNING:
Do not bring an open flame close to the battery
when working.
CAUTION:
• Prior to charging, corroded terminals should
be cleaned with a brush and common caustic
soda solution.
• Be careful since battery electrolyte overflows
while charging the battery.
• Observe instructions when handling the bat-
tery charger.
• Before charging the battery on the vehicle,
disconnect the battery ground terminal to pre-
vent damage of generator diodes or other elec-
trical units.
1. JUDGEMENT OF BATTERY IN
CHARGED CONDITION
1) Specific gravity of electrolyte should be held
within the specific range of 1.250 — 1.290 for one
hour or more.
2) Voltage per battery cell should be held at a spe-
cific value in a range of 2.5 — 2.8 V for one hour or
more.
2. CHECK CONDITION OF CHARGE WITH
HYDROMETER
3. NORMAL CHARGING
Charge the battery at the current value specified by
manufacturer or at approximately 1/10 of battery’s
ampere-hour rating.
4. QUICK CHARGING
Quick charging is a method that the battery is
charged in a short period of time with a relatively
large current by using a quick charger.
Since a large current flow raises electrolyte temper-
ature, the battery is subject to damage if the large
current is used for prolonged time. For this reason,
the quick charging must be carried out within a cur-
rent range that will not raise the electrolyte temper-
ature to 40°C (104°F) or more.
Also the quick charging is a temporary mean to
bring battery voltage up to some level, and battery
should be charged slowly with low current as a rule.
CAUTION:
• Observe the items in “3. NORMAL CHARG-
ING”.
• Never use 10 A or more when charging the
battery because it will shorten the battery life.
Hydrometer
indicator
State of charge Corrective action
Green dot 65% or more Load test
Dark dot 65% or less Charge battery
Clear dot Low electrolyte
Replace the battery*
(If cranking is difficult)
* Check electrical system before replacement.
SC-00094
1.28
Specific gravity [20˚C (68˚F)]
Specific gravity and state of charge
Complete charge
Charging condition
1.26
1.24
1.22
1.20
1.18
1.16
1.14
1.12
100% 75% 50% 22% 0%
(%)