CHARGER AND
CHARGING PROCESS
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Q. 1 What is the basic principle of the charger and
what are its main components?
A. 1
The charger is used to convert the incoming power source to the same type and voltage of the battery.
Recent advancements in technology have made chargers very efficient and easy to use.
There are two basic types of chargers: the on-truck type and the off-truck type. The on-truck type is
usually chosen by those who have one forklift that is used for one workshift. The off-truck type is used
by those who have one or more spare batteries for two or three workshifts or in countries where the on-
truck type is not available.
• Basic Principle of the Charger
Power Source Transformer Rectifier Output
(Single-phase; (Reduced input voltage (Converts the alternating (for Battery)
Three-phase) to voltage near that current “AC” to direct
of the battery) current “DC”)
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Q. 2 Chargers are only available in 200V and 400V. How can
you cover all areas with just two types of chargers?
A. 2
As different voltages are used in different regions, Toyota offers chargers that are compatible with virtually any
voltage.
Toyota offers 200V and 400V chargers. This is because voltage can vary according to country and region. Even
within the same region, there may be small differences in voltage. While this normally would not be a problem with
general appliances, with a charger it can result in over charging or under charging a battery. Since these small
differences in voltage exist, Toyota offers chargers that can be adjusted to the local voltage using a different tap
once the voltage has been measured and confirmed at the power supply outlet.
Toyota charger can
200 V handle
or all voltages!
400 V ?
Adjusting the Charger For 200 V
Measured Voltage Tap
1. Measure the voltage at the power supply outlet. Based on the
180 – 199 V 200
result, select the proper tap from the table at the right.
200 – 209 V 210
2. Select the tap from the table. For the 200 V charger, select from 210 – 219 V 220 ❍
200, 210, 220 and 230. 220 – 229 V 230
3. Select the tap from the table. For the 400 V charger, select from
For 400 V
340, 360, 380, 400, 420, 440 and 460. (Refer to the table on the
Measured Voltage Tap
right.)
320 – 339 V 340
340 – 359 V 360
360 – 379 V 380
380 – 399 V 400 ❍
400 – 419 V 420
420 – 439 V 440
440 – 459 V 460
❍ : At the time of shipping.
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Q. 3 When installing a new charger, is it all right to use the
existing circuit breaker?
A. 3
Consult with an electrician to determine whether or not the circuit breakers have the proper amperage and current
leakage ratings.
A battery charger will require more current than conventional appliances. That is why it is important to check
whether or not the existing breaker has the proper AC amperage rating. If they do not, they must be replaced. Be sure
to recommend that a current leakage breaker also be installed.
Calculating the AC Power Supply Capacity of a Charger
1. Check the kVA value displayed on the charger.
2. Check the AC voltage.
3. Check that the power supply is 3-phase.
4. Calculate the following formula:
kVA x 1000
(kVA x 1000) ÷ 1.732 x Voltage = Required AC ( =
Required AC )
Power Supply Phase x V Power Supply
Example: Assuming
kVA of Charger: 4.9 kVA
Voltage: 200V
Power Supply: 3-Phase AC Current
(4.9 kVA x 1000) ÷ (1.732 x 200) = 14.1 (A)
This means that each charger will require a power supply capacity of more than 14.1 A.
Note:
Always carefully check the phase of the current. In most countries, the voltage of a 3-phase power supply is twice
that of a single-phase power supply. Moreover, your customer may be using different power phases in the same
building.
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Q. 4 Why does a charger have to be grounded?
A. 4
All electric equipment requires grounding. Grounding is a safety precaution for preventing electrical shock by
diverting leaking voltage to the ground, which is a conductor of electricity.
When electrical equipment is completely grounded, the electricity will flow to the ground in the unlikely event of a
problem such as improper insulation or short circuit, eliminating the danger of electrical shock if the equipment is
touched. Conversely, if the electrical equipment is not completely grounded, there is the danger that electrical shock
can occur. Moreover, safety is further enhanced by the installation of a current leakage breaker.
Grounded
Current Leakage Breaker
A current leakage breaker detects current leakage and immediately interrupts the power supply circuit to prevent
electrical shocks or fires from occurring. A current leakage breaker should be strongly recommended to customers
who have extensive unmanned night-shift operations.
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Q. 5 What precautions should I take when using the
charger?
A. 5
There are some cautions when using the charger.
1. Never connect the wall-mounted power source directly to the
controller. (This will damage the controller)
2. The area should be well ventilated as hydrogen gas is given off
during the charging process.
3. No open flame should be used near a charging battery for the same
reason.
4. Provide fire extinguishing equipment at the charging station.
5. Open the battery hood during charging. (There is no need to open
the caps for each of the cells.)
6. An eye wash basin and shower should be provided in case
electrolyte is accidently splashed into the eyes or on the clothing.
Note:
There is a danger of explosion when the concentrations of hydrogen gas exceeds 3.8%. In addition, incidents have
been reported of hydrogen gas explosions being caused by a welding arc 10 meters away from the charging battery.
Always stress to your customers that good ventilation is essential when charging a lead-acid battery.
Grounded
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Q. 6 Are there different types of charging?
A. 6
There are three popular types of charging: normal charging, equalized charging and supplemental
charging.
1. Normal Charging
This is charging when it is needed — when 75% of the battery’s capacity has been discharged. The
amount of time needed for charging a battery will vary according to the depth of the discharge, but it
can usually be done in less than 10 hours.
2. Equalized Charging
With normal charging only, the innate differences in the performance of each cell will appear — some
will have more charge than others. To compensate for this, it is necessary that the battery be
periodically overcharged so that all cells come to the same charging state. This is equalized charging.
Generally, this should be done about once a month. It is important to remember that the equalized
charging of the battery too frequently can be just as damaging to its long-term performance as
overdischarging it with regularity. (Toyota on-truck type chargers have a computer controller that will
automatically switch to equalized charging when necessary.)
3. Supplemental Charging
Supplemental charging is charging for only a short time whenever the forklift is not being used, such
as during a lunch break.
Service Life
The demands placed on the battery will affect its service life. Under normal working conditions, with
proper care, and if the battery is not regularly overdischarged, the battery can be charged
approximately 1,200 times; in other words, about 4 years of conventional service.
(For more information, see Question 11 in the Batteries Section, page 22.)
Point to Remember
An engine forklift can be refueled faster than an electric forklift can be charged, but if the charging
is done at night when no one is working, this will not make any difference.
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Q. 7 When is the best time for supplemental charging?
A. 7
Generally speaking, the best time for charging the forklift is after it has finished the work for the day. In some cases,
however, when there is still work to be done, supplemental charging may be better for the battery.
(An hour of charging can bring about a 10 to 15% recovery.)
Supplemental charging increase the number of charge cycles and , when compared to normal usage, results in shorter
battery life. However, continuing to work on an over-discharged battery (when discharge exceeds 75% of capacity)
is much worse for a battery. While battery life will depend on how the forklift is used, it is generally better to
perform supplemental charging instead of continuing to work on a overdischarged battery.
Relationship Between Supplemental Charging and Battery Life
Depth of Discharge Little Discharge Less than 75% More than 75%
Normal Charging Only Optimum Acceptable
Possible to extend service life
by supplemental charging
Normal Charging + Not Acceptable Good Optimum
Supplemental Charging Increases load on electrode Supplemental charging has no
plate shortens service life effect on service life
Supplemental Charging Only Not Acceptable
Shortens service life if complete charging is not performed
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Q. 8 How long does charging take?
A. 8
The time required for charging will vary among models, but normally it will take a approximately of 10 hours to
charge a battery that is 100% discharged.
When the voltage in each cell reaches 2.4 V (Actuating
point), the timer on the charger starts to operate and the
charging is completed four hours later. (Six hours later
for equalized charging.) Moreover, when the Actuating
(V)
point voltage is exceeded, the water in the battery starts
2.7 (A)
electrolysis and create hydrogen and oxygen gases.
Battery Voltage (V/cell)
2.6 60
Charging Current
2.5 50
Charging Current
Note:
2.4 HVR 40
Actuating Point
In the past, battery chargers only had one timer to shut 2.3 30
off the charger at a certain pre-set time after the battery 2.2 Charging Voltage 20
reached 2.4 volts. Note that if for some reason the 2.1 10
voltage did not reach 2.4 volts, or if the timer did not
work properly, the charger would continue charging and
damage the electrode plate.
Timer Working
The battery chargers used today have a second timer that
Charging Time
automatically shuts off the charger after 16 hours, Start of Charging Completion of Charging
regardless of the function of the first timer, and a red
LED lamp will flash to indicate that there was a problem
during the charging.
...10 hrs
100% of Disharge
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Q. 9-1 What is charging efficiency?
A. 9-1
Approximately 15 to 20% more electrical power (overcharge amount) is required to charge a battery to 100% of its
capacity. This ratio of the power required to charge a battery is known as the charging efficiency or the charge ratio.
When this additional 15 to 20% is forced into the battery, it causes the water (H2O) to break down and create
hydrogen and oxygen gases.
Q. 9-2 What happens if the battery charging is stopped
without the extra 15 to 20% electrical power?
A. 9-2
The extra 15 to 20% more electrical power forced into the battery is not wasted and actually causes mixing by
hydrogen and oxygen gases created by a chemical reaction that helps to evenly mix the electrolyte within each cell.
If this mixing did not take place, there would be an unevenness in the specific gravity of the cells and the standard
voltage of approximately two volts could not be attained.
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