Field Load Test - Invacare Pronto M91 Service Manual

Field Load Test

NOTE: For this procedure, refer to FIGURE 3.1 on page 34.
NOTE: The following test can also be performed through the controller of the wheelchair along
with a remote programmer. Refer to the electronics manual supplied with each wheelchair.
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 (2.5 for a pair), replace the batteries.
To spot this problem, test batteries under load.
Use a digital voltmeter to check battery charge level at the charger connector. It is located
on the joystick.
NOTE: READ these instructions CAREFULLY and the manufacturer's instructions on the
digital voltmeter before using the digital voltmeter.
NOTE: Invacare recommends that ONLY a qualified technician perform this test.
1. Ensure that power is OFF.
2. Make sure battery is fully charged. An extremely discharged battery will exhibit the
same symptoms as a bad one.
3. Remove the footrests from the wheelchair.
4. Connect the voltmeter leads to the charger port on the wheelchair as shown in
FIGURE 3.1 on page 34. Most digital voltmeters are not affected by polarity, however,
analog meters (meters with swinging needles) can be and should be used carefully.
A good meter reading should be 25.5 to 26 VDC.
When performing STEPS 5 and 6, ensure feet are clear from casters and wall
otherwise injury may occur.
5. Sit in wheelchair and place feet against a wall, workbench or other stationary object.
6. Turn the power ON and carefully push the joystick forward, trying to drive the
wheelchair through the stationary object.
NOTE: This puts a heavy load on the batteries as they try to push through the stationary object. If
the wheels spin, have two individuals (one on each arm) apply as much downward pressure as
possible on the arms of the wheelchair.
7. Read the meter while the motors are straining, no longer than 3 to 4 seconds, to
determine the voltage under load.
NOTE: If the voltage drops more than 2.5 volts from a pair of fully charged batteries while under
load, they should be replaced regardless of the unloaded voltages.
Part No. 1125038
SECTION 3—SAFETY INSPECTION/TROUBLESHOOTING
WARNING
33
Pronto® M91™and M94™