Electrical System Checks; Safety Precautions - Yale 524150797 Maintenance Manual

2200 YRM 1508
WARNING
Disconnect the battery
compartment cover or inspecting or repairing the
electrical system. If a tool causes a short circuit,
the high current flow from the battery can cause
personal injury or property damage.
The capacitor in the transistor controller can hold
an electrical charge
disconnected. To prevent electrical shock and
personal injury, discharge the capacitor before
inspecting or repairing any component in the drive
unit compartment. Wear safety glasses. Make
certain the battery has been disconnected.
All checks, adjustments, and repairs in the drive unit
compartment are done with the compartment cover
removed. Remove the drive unit compartment cover
for access to the electrical components. See
Accessing the Drive Unit Compartment in AC Motor
Repair 0620YRM1513.

SAFETY PRECAUTIONS

WARNING
Some checks require
reconnected. DO NOT connect the battery until the
procedure tells you to do so. Make sure the drive
wheel is raised to prevent truck movement and
possible injury. Raise the drive wheel. The blocks
must prevent the lift truck from falling and causing
personal injury or property damage.
CAUTION
To avoid controller damage, always disconnect the
battery before disconnecting any cables from the
controller. Discharge the capacitor, and never put
power to the controller with any power wire
disconnected. Never short any controller terminal
or motor terminal to the battery. Make sure to use
proper procedure when servicing the controller.
1. Block lift truck so the drive tire is raised slightly off
the floor to prevent unexpected movement when
making checks.
2. Turn the key switch to the OFF position and
disconnect the battery.

Electrical System Checks

before opening
after the battery
the battery to
3. Discharge the capacitors. See Special
Precautions in this section.
the
NOTE: These checks require a volt-ohmmeter with a
meter movement. Most digital meters will not operate
correctly for some of these checks. Specific checks
require additional equipment.
NOTE: The correct meter polarity is necessary for the
checks. The voltage checks are made between the
is
point indicated in Table 1 and battery negative.
Connect the meter negative to battery negative.
NOTE: The battery does not have to be removed to
check the specific gravity.
4. Using a hydrometer, check the specific gravity of
the battery. If the specific gravity is less than
1.260, the battery is not fully charged or is
damaged. A fully-charged battery has a specific
gravity of 1.270 to 1.290. A discharged battery
has a specific gravity of approximately 1.165.
5. The electric lift truck has a two-wire system. The
frame must not be a common electrical path.
Check for 50,000 ohms or more between each
battery terminal and a clean connection on the
frame. Remove any circuit paths between the
controller and the frame of the lift truck, such as a
be
dirty battery case. Carbon dust in a motor or other
parts can cause a circuit path. Check for
additional equipment that may cause a circuit
path to the frame.
6. Check for voltage between each terminal of the
connector that fastens to the battery and a clean
connection on the frame. Normally, there is small
voltage (less than 30 percent of the battery
voltage) between the battery and the frame, even
though the resistance is very high. A higher
voltage can indicate a dirty battery or a damaged
battery. Clean the battery and battery
compartment as necessary.
7. Visually check for parts or wires that are loose or
damaged.
NOTE: Make an identification of any wires before you
disconnect them. The wires must be reconnected
correctly after checks or repairs.
Electrical System Checks
3