Battery Charging - Suzuki XL7 2007 Service Manual

Battery Charging

Special tool
J 42000 Battery Tester
• For best results, use an automatic taper-rate battery charger with a voltage capability of 16 volts.
• The charging area should be well ventilated.
• Do not charge a battery that appears to be frozen. Allow the battery to warm to room temperature and test it using
the J 42000 before charging.
Battery State of Charge
NOTE
Using voltage to determine the batteries state of charge (SOC) is only accurate after the battery has
been at rest for 24 hours. This is enough time for the acid in each cell to equalize. If the battery has
been charged or discharged in the past 24 hours, the battery SOC will only be an estimate.
The maintenance-free batteries SOC is estimated by reading the voltage of the battery across the battery terminals.
Because the voltage is affected by current flow into or out of the battery, the engine must be stopped and all electrical
loads turned OFF, including parasitic loads, when checking the voltage. The voltage can also be affected if the battery
has just been charged or discharged, so it is important to consider what has happened to the battery in the time just
before testing. Use the following procedure to determine the batteries SOC:
1. Be sure all electrical loads are turned OFF.
2. Determine whether the battery has been used in a vehicle or charged within the past 12 hours.
– If the answer is no, the terminal voltage will be stabilized and no action is necessary before reading the voltage.
Skip to step 3.
– If the answer is yes, terminal voltage will not be stabilized and you should wait 12 hours since the last time the
battery was used.
3. Estimate the battery temperature by determining the average temperature to which the battery has been exposed
for the past 12 hours.
NOTE
The table is accurate to 10 percent only after the battery has been at rest for 12 hours.
4. Measure the battery voltage at the battery terminals. Refer to the following table to determine the SOC according
to the estimated battery temperature:
Battery Voltage
12.75 V
12.7 V
12.6 V
12.45 V
12.2 V
12.0 V
Use the SOC information as follows:
• A battery with a SOC that is below 65 percent must always be recharged before returning it to service or continuing
storage.
• A battery with a SOC that is 65 percent or greater is generally considered to be charged enough in order to be
returned to normal service or in order to continue storage. However, if the battery is being used in slow traffic or with
short drive times, or if the temperature is very hot or very cold, the battery should be fully charged, to at least 90
percent, before returning it to service or continuing storage.
Charging Time Required
The time required to charge a battery will vary
depending upon the following factors:
• The battery charger capacity—The higher the charger
amperage, the less time it will take to charge the
battery.
% Charge at 0°C (32°F)
100%
100%
90%
75%
65%
40%
• The SOC of the battery—A completely discharged
battery requires more than twice as much charging
time as a half charged battery. In a discharged battery
with a voltage below 11 volts, the battery has a very
high internal resistance and may only accept a very
low current at first. Later, as the charging current
causes the acid content to increase in the electrolyte,
Charging System:
% Charge at 25°C (75°F)
100%
90%
75%
65%
45%
20%
1J-32