Procedure 2 - Troubleshooting; Field Load Test; Using Hydrometer To Check Battery Cells (Lead Acid) - Invacare Arrow RWD Service Manual

PROCEDURE 2
This Procedure Includes the Following:

Field Load Test

T
Using Hydrometer To Check Battery Cells (Lead
R
Acid)
O
U Motor Testing
B
Motor Brush Inspection
L
E Electro-Mechanical Parking Brake Testing
S
H
FIELD LOAD TEST (FIGURE 1)
O
O
NOTE: The following test can also be performed through
T
the controller of the wheelchair along with a remote pro-
I
grammer. Refer to the individual CONTROLLER
N
MANUAL supplied with each wheelchair.
G
Old batteries lose their ability to store and release power, due
to increased internal resistance. This means that as you try
to take power from the battery, some of that power is used up
in the process of passing through the battery, resulting in less
voltage at the posts. The more power drawn, the lower the
voltage available. When this lost voltage drops the output 1.0
volts under load (2.0 for a pair), replace the batteries.
Testing under load is the only way to spot this problem.
While special battery load testing equipment is available,
it is costly and difficult to transport.
Use a digital voltmeter to check battery charge level at the charger
connector. It is located on the base of the wheelchair frame.
NOTE: READ the instructions CAREFULLY before us-
ing the digital voltmeter.
NOTE: Invacare recommends that ONLY qualified ser-
vice personnel perform this test.
1. Ensure that power is OFF.
2. Make sure battery is fully charged. An extremely dis-
charged battery will exhibit the same symptoms as a
bad one.
3. Remove the footrests from the wheelchair and place
the CASTERS of the wheelchair against a wall,
workbench or other stationary object.
4. Place the voltmeter leads into the charger plug on the
wheelchair. Most digital voltmeters are not affected by
polarity, however, analog meters (meters with swing-
ing needles) can be and should be used carefully. A
good meter reading should be 25.5 to 26 VDC.
5. Have two (2) individuals (one [1] on each arm) apply
as much downward pressure as possible on the arms
of the wheelchair.
6. Turn the wheelchair ON and push the joystick for-
ward, trying to drive the wheelchair through the sta-
tionary object. This puts a heavy load on the batteries
as they try to push through the stationary object. Read
the meter while the motors are straining to determine
the voltage under load.
NOTE: If the voltage drops to less than 23.5 volts from a
pair of fully charged batteries while under load, they should
be replaced regardless of the unloaded voltages.
Battery Charger
Connector
Digital Voltmeter
FIGURE 1 - FIELD LOAD TEST
USING HYDROMETER TO CHECK
BATTERY CELLS (LEAD ACID)
(FIGURE 2)
NOTE: Perform this procedure when a digital voltmeter is
not available.
WARNING
NEVER smoke or strike a match near the
batteries. If the caps of the battery cells
are removed, NEVER look directly into
them when charging the battery.
The use of rubber gloves and chemical
goggles or face shields is recommended
when working with batteries.
12
TROUBLESHOOTING
(-)
(+)