Battery Charging
Special Tools
EL 42000 Battery Tester
For equivalent regional tools, refer to
Special Tools .
Diagnostic Aids
• |
For best results, use an
automatic taper-rate battery charger with a voltage capability of
16 V. |
• |
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 EL 42000 Battery Tester
before charging. |
Battery State of Charge
Note: Using voltage to
determine the batteries state of charge 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 state of charge will
only be an estimate.
The maintenance-free batteries state of charge 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 state of charge:
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 state of charge according to the estimated battery
temperature: |
Battery Voltage
|
% Charge at 0°C (32°F)
|
% Charge at 25°C (75°F)
|
12.75 V
|
100%
|
100%
|
12.7 V
|
100%
|
90%
|
12.6 V
|
90%
|
75%
|
12.45 V
|
75%
|
65%
|
12.2 V
|
65%
|
45%
|
12.0 V
|
40%
|
20%
|
|
|
Use the state of charge information as follows:
• |
A battery with a state of
charge that is below 65 percent must always be recharged before
returning it to service or continuing storage. |
• |
A battery with a state of
charge 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. |
• |
The state of charge 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 V, 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, the charging current will increase.
Extremely discharged batteries may not activate the reversed
voltage protection in some chargers. Refer to the manufacturer's
instructions for operating this circuitry. |
• |
The temperature of the
battery-The colder the battery is, the more time it takes to
recharge the battery. The charging current accepted by a cold
battery is very low at first. As the battery warms, the charging
current will increase. |
Charging Procedure
|
Caution: Turn OFF the ignition when connecting or disconnecting
the battery cables, the battery charger or the jumper cables.
Failure to do so may damage the ECM/PCM or other electronic
components. |
Caution: Refer to
Fastener Caution .
When charging side-terminal batteries with the battery cables
connected, connect the charger to the positive cable bolt and to a
ground located away from the battery. When charging side-terminal
batteries with the battery cables disconnected, install the battery
side terminal adapters and connect the charger to the adapters.
Tighten
Tighten the battery side terminal adapters to 15 N·m (11 lb
ft).
Use the following procedure to charge the battery:
2. |
Ensure that all of the battery
terminal connections are clean and tight. |
3. |
Connect the charger positive
lead to the battery positive terminal on the battery or the remote
jumper stud underhood. |
|
Caution: Do
not connect the negative charger lead to the housings of other
vehicle electrical accessories or equipment. The action of the
battery charger may damage such equipment. |
4. |
Connect the negative charger
lead to a solid engine ground or to a ground stud in the engine
compartment that is connected directly to the battery negative
terminal, but away from the battery. If the negative battery cable
is disconnected and a terminal adapter is being used, connect
directly to the adapter. |
5. |
Turn ON the charger and set to
the highest setting for normal charging. |
6. |
Inspect the battery every half
hour after starting the battery charger. |
|
• |
Charge the battery until the
taper-rate charger indicates that the battery is fully
charged. |
|
• |
Estimate the battery
temperature by feeling the side of the battery. If it feels hot to
the touch or its temperature is over 45°C (125°F),
discontinue charging and allow the battery to cool before resuming
charging. |
|